JP3709614B2

JP3709614B2 - Raising seedling sheet and seedling raising method using the raising seedling sheet

Info

Publication number: JP3709614B2
Application number: JP17441696A
Authority: JP
Inventors: 藤芳廣斎
Original assignee: Hokuetsu Paper Mills Ltd
Current assignee: Hokuetsu Paper Mills Ltd
Priority date: 1996-06-14
Filing date: 1996-06-14
Publication date: 2005-10-26
Anticipated expiration: 2016-06-14
Also published as: JPH1017A

Description

【０００１】
【発明の属する技術分野】
本発明は、主に水稲の育苗に使用される育苗シート及びその育苗シートを用いた育苗方法に関し、さらに詳しくは優れた植物育成適性と十分な強度を併せ持ち、育苗作業の改善及び効率向上を図ることのできる育苗シート及びその育苗シートを用いた合理的かつ効率的な育苗方法に関する。
【０００２】
【従来の技術】
現在、水稲の育苗方法は、育苗箱に培土を床土として入れ、灌水した後、播種し、覆土し、出芽、緑化し、稚苗段階で田植機によって本田に移植するのが一般的な方法である。
【０００３】
【発明が解決しようとする課題】
一連の育苗作業の中で最もトラブルの発生しやすいのが苗を植え根張りをさせたマットを育苗箱から取り上げ田植機に装着する作業である。根張りが不十分で、マット形成が不良となると、マットを取り上げる際にマットが形くずれしたり、ばらけたりして作業が困難となる。
【０００４】
マット形成不良の発生原因としては、培土の品質不良、灌水量、育苗室温度などの育苗条件管理の不適あるいは気温、日照量などの気候条件等の影響が考えられる。また、一般農家では兼業農家が多く人手不足等のため、あまりきめ細かい育苗条件管理ができない場面が多いことも一因である。
一方、育苗センターでは多量の育苗を行うため、一般に育苗設備が整っていて育苗条件を管理する上では有利である。しかし、多数の農家の育苗を代行するため、万が一マット形成不良等が発生した場合には責任問題となり、事態は深刻である。また、育苗センターでは多量の育苗を処理するために、ローテーションを組み計画的に対応する都合上、気温や日照量がまだ必ずしも好適条件とならない時期から育苗を開始しなければならなかったり、できるだけ育苗期間を短縮して育苗ローテーションをはやくすることで育苗効率を上げ生産性の向上を図る必要があり、乳苗育苗が指向されつつある。
【０００５】
乳苗育苗は稚苗育苗に比べ、▲１▼育苗期間を約１／３に短縮できる。▲２▼播種量を２０〜５０％程度増量できる。▲３▼本田単位面積当りの育苗箱数が少なくて済む。▲４▼育苗ローテーションが効率化できる。▲５▼結果的に低コストとすることができる。といった利点を有する。
しかし、培土を床土とする育苗では、乳苗段階においては根張りが少なくマット形成が不十分でばらけてしまい田植機に装着することができない。近年、繊維素系あるいは無機繊維系の各種合成培地マットが開発されているが、かかる合成培地マットは根の食い込みを良くし根上りを防止するために、ごく少量のバインダーによる乾式法により製造されるものがほとんどであり、低密度で、かつ強度も著しく弱く、マット補強という機能を十分に発現できるものは見あたらない。一部に乳苗育苗に供されているものもあるが、マット補強力は十分とは言い難く、乳苗育苗における田植機装着作業性も必ずしも良好ではない。
【０００６】
一方、湿式抄造によるものは、一般に繊維間接合が強くなりやすく、根の貫通できるようなマットを得ることは困難なためほとんどなかったが、先般、本発明者は特定の高吸水性樹脂を繊維間隙に均一に散在せしめ、吸水時に該高吸水性樹脂が吸水膨張して繊維間結合を破断または弛緩するようにすることにより根の貫通適性を確保できることを提案した。
しかし、吸水膨張した状態の高吸水性樹脂を含有する原料スラリーによる抄造は、抄造網に吸水膨張状態の高吸水性樹脂が付着しやすいなど製造工程上の問題が発生することがあるとともに、吸水時のシートはきわめて弱くなり、場合によってはマット補強力が不足することもある。また、培土を床土として使用する育苗方法に慣れたユーザーにとって、床土を使わない合成培土マットによる育苗は技術的に飛躍があり、容易には受け入れにくいこともあって、今のところ、合成培地マットによる育苗の普及率はきわめて低いのが現状である。
【０００７】
よって、稚苗育苗でのマット形成不良による田植機への装着時の支障を解消でき、また、乳苗育苗にも安心して対応できるような育苗資材あるいは育苗方法の出現が強く求められていた。
本発明は上記課題を解決するためになされたもので、優れた植物育成適性と十分な強度を併せ持ち、たとえマット形成が不良でも田植機への装着を可能とし、また、乳苗育苗にも対応できるなど、育苗作業における作業性改善及び効率向上を図り得る育苗シートとその育苗シートを用いた合理的かつ効率的な育苗方法を提供することを目的とするものである。
【０００８】
【課題を解決するための手段】
本発明者は、上記課題を最も合理的かつ効果的に解決するため熟慮のすえ、特にバインダーを使わずとも繊維間結合（水素結合）という結合力によりシート形成できるセルロース系繊維による湿式抄造の利点を活かしつつ、根が貫通できるように、その繊維間結合を可能な限り弱めるにはどうすればよいかという観点から、化学処理を受けておらず、かつ実質的にフィブリル化されていないセルロース系繊維の検討を進めた。
かかるセルロース系繊維はほとんど繊維間結合力を有さないか有しても非常に繊維間結合力が弱いものであるため、抄造性が悪く通常それ単体で抄造できるものではなく、薬品処理による解質あるいは叩解等を施して、ある程度の繊維間結合力を付与せしめてからでないと抄造には適用されないものである。
【０００９】
しかして、本発明者は、あえて、かかる抄造には不向きな素材をできるだけそのままの形態で用いて抄造する技術を指向して検討を重ねた結果、化学処理を受けておらず、かつ実質的にフィブリル化されていないセルロース系繊維を高含有するシートを形成せしめ、厚さ及び密度を所定範囲とし、さらに親水化処理を施し、所定の湿潤条件下の湿潤引張強度と湿潤裂断長を特定範囲とすることにより、育苗時に、床土の下敷きとして利用した場合に、根の貫通適性とマット補強という相反する機能を両立できること、すなわち、かかる方法で育苗すれば、根の貫通性が良好であると同時に、田植機への装着時に、たとえ根張りが少なくマット形成が不良でも下敷シートの補強効果によって支障なく作業できること、さらに、乳苗段階での田植機への装着も可能ならしめ得ることをつきとめ本発明を完成した。
【００１０】
すなわち、本発明に係る育苗シートは、化学処理を受けておらず、かつ実質的にフィブリル化されていないセルロース系繊維を５０〜９０重量％含有する親水化処理シートであって、該シートの厚さが０．８〜５ｍｍ、密度が０．１〜０．５ｇ／ｃｍ³ であり、かつ２０℃の蒸留水に５分間浸漬後の該シートの繊維配向方向及びこれと直角をなす方向について測定して両者の平均を求めた湿潤引張強度（ＪＩＳＰ−８１１３に基づく測定）及び湿潤裂断長（ＪＩＳＰ−８１１３に基づく測定）のそれぞれは該湿潤引張強度が０．２〜１．０ｋｇ／１５ｍｍ幅で、該湿潤裂断長が０．０２〜０．１ｋｍであるものである。
【００１１】
本発明に係る育苗シートは、化学処理を受けておらず、かつ実質的にフィブリル化されていないセルロース系繊維を５０〜９０重量％好ましくは６０〜８０重量％含有しなければならない。該含有率が５０重量％未満では根の貫通に支障が出て根上りを発生しやすくなる。反対に９０重量％を超えた場合は、抄造性が悪化するとともに、得られるシートの強度が弱過ぎ十分なマット補強効果を得ることができない。
化学処理を受けておらず、かつ実質的にフィブリル化されていないセルロース系繊維としては木材粉砕物、木毛、木粉及び木材屑や木片を繊維化した木質系繊維化物等の各種木材繊維あるいは機械パルプのごとき化学処理を受けていない木材パルプ等を使用できる。
【００１２】
また、本発明の育苗シートにおいては、所定のシート強度を得るために、上記した化学処理を受けておらず、かつ実質的にフィブリル化されていないセルロース系繊維以外のセルロース系繊維を併用するのが望ましい。かかるセルロース系繊維としては、針葉樹系あるいは広葉樹系の化学パルプ、セミケミカルパルプ等の木材パルプあるいは各種古紙、バガス、ワラ、リンターなどの中から選ばれる１種類もしくは２種類以上を併用して使用することができる。かかるセルロース系繊維の本発明に係る育苗シート中における含有率は５〜４０重量％とするのが好ましい。該含有率が５重量％未満では所定のシート強度が得られないことがあり得る。反対に４０重量％を超えた場合は、シート強度が強くなり過ぎ、根の貫通性に支障が出て根上りを生ずることがあり得る。
【００１３】
本発明の育苗シートの厚さは、０．８〜５ｍｍ好ましくは１．５〜３ｍｍでなければならない。該厚さが１ｍｍ未満では強度が不足し、十分なマット補強効果を得ることができない。反対に５ｍｍを超えた場合は、根の貫通性に支障が出て根上りを生じやすくなる。
本発明の育苗シートの密度は、０．１〜０．５ｇ／ｃｍ³ 好ましくは０．１５〜０．４ｇ／ｃｍ³ でなければならない。該密度が０．１ｇ／ｃｍ³ 未満ではシート強度が弱すぎ十分な効果が得られない。反対に０．５ｇ／ｃｍ³ を超えた場合は、根の食い込みが悪化し、根上りを生じやすくなる。
【００１４】
本発明の育苗シートは親水化処理を施さなければならない。本発明の育苗シートは化学処理を受けておらず、かつ実質的にフィブリル化されていないセルロース系繊維を高含有しているため、親水化処理を施さないと育苗シートとして必要な吸水性を確保することができない。
親水化処理は特に限定するものではなく、スルホン酸型、カルボン酸型、りん酸エステル型、硫酸エステル型、第四級アンモニウム塩型等の各種界面活性剤あるいは高級アルコール類、多価アルコール類、シリコン系親水化剤、ＰＶＡ系親水化剤などの親水性付与剤を内添したり含浸もしくは塗布するなどすればよい。
また、かかる親水性付与剤の添加量は特に限定されるものではないが、重要なことはシートの湿潤引張強度と湿潤裂断長が本発明で特定する範囲内となるような添加量とする必要がある。
【００１５】
本発明の育苗シートを２０℃の蒸留水中に５分間浸漬した後に、ＪＩＳＰ−８１１３に基づいて測定した湿潤引張強度は、繊維配向方向及びこれと直角をなす方向の平均で０．２〜１．０ｋｇ／１５ｍｍ幅、好ましくは０．３〜０．７ｋｇ／１５ｍｍ幅でなければならない。また、該湿潤引張強度から求めた湿潤裂断長は０．０２〜０．１ｋｍ、好ましくは０．０３〜０．０７ｋｍでなければならない。前記した湿潤引張強度が０．２ｋｇ／１５ｍｍ幅未満もしくは前記した湿潤裂断長が０．０２ｋｍ未満のときは、十分なマット補強効果が得られず、根張りの少ない時にマットを取り上げる際に育苗シートが破断するなどの支障を来しやすい。反対に前記した湿潤引張強度が１．０ｋｇ／１５ｍｍ幅を超えるもしくは前記した湿潤裂断長が０．１ｋｍを超える場合は、根の食い込みが悪化し、根上りを生じやすくなる。
【００１６】
本発明の育苗シートは、上述したように化学処理を受けておらず、かつ実質的にフィブリル化されていないセルロース系繊維を高含有せしめ、親水化処理を施し、かつ厚さ、密度、湿潤引張強度及び湿潤裂断長をそれぞれ所定範囲とすることにより、根の貫通適性とマット補強力を併せ持たせたものであるが、クレー、タルクなどの無機填料あるいはロックウール繊維、ガラス繊維、セラミック繊維などの無機繊維を配合することにより、さらに繊維間結合を弱めて根の貫通性を向上せしめることができる。
また、必要に応じて各種合成樹脂ラテックス等のバインダーの類を配合してもよいが、この場合、根の貫通性等を阻害しないようにその添加量をごく少量に抑えるべきことは当然である。
さらに、必要に応じて、硫安、塩安、尿素等の窒素肥料、あるいは硫酸カリ、塩化カリ等のカリ肥料もしくは過リン酸石灰、リン安等のリン酸肥料などを配合したり、硫酸、クエン酸、フミン酸、ニトロフミン酸、ピートモス等のＰＨ調整剤及び防カビ剤等を配合してもよい。なお、湿式抄造で内添により肥料を配合する場合、水に溶けにくい粉体状の緩効性肥料を用いるのがより効果的である。
【００１７】
本発明の育苗シートを製造するには、乾式成形によってもよいが、湿式抄造によるのがより好ましい。乾式成形の場合、十分なマット補強効果を発現するに足るシート強度を得るには、各種合成樹脂ラテックス等のバインダーの類を相応量配合することが不可欠となり、根の貫通適性とマット補強力とを両立させることがかなり難しくなる場合があり得る。これに対し、湿式抄造の場合、必ずしも前記したバインダーの類を使わなくとも、抄造過程で成生するセルロース系繊維同志の水素結合による繊維間結合でもって、十分なマット補強効果を発現するに足るシート強度を得ることができるので、根の貫通適性とマット補強力とを両立させることができる。
【００１８】
ここでは、湿式抄造により本発明の育苗シートを製造する場合について、さらに説明する。すなわち、本発明の育苗シートを湿式抄造により製造するには、化学処理を受けておらず、かつ実質的にフィブリル化されていないセルロース系繊維を所定量含有する原料スラリーを調成し通常の抄造法により抄造すればよい。そして、前記した各種親水性付与剤を原料スラリー中に内添するか、シートを形成せしめてから含浸もしくは塗布するなどして親水化処理を施せばよい。また、必要に応じて叩解処理を施してもよいが、原料スラリー中の化学処理を受けておらず、かつ実質的にフィブリル化されていないセルロース系繊維をかかる状態に維持し、繊維間結合力を発現しにくい状態を保たねばならない。従って、実質的にフィブリル化の起こらないごく弱い条件で叩解するか化学処理を受けておらず、かつ実質的にフィブリル化されていないセルロース系繊維の処理を別経路とし、かかるセルロース系繊維は叩解しないで使用する等の工夫が必要である。抄造については、通常の長網、円網あるいは傾斜網等の抄造網上に原料スラリーを供給し、濾過、脱水した後、圧搾・乾燥すればよい。また、必要に応じて各種コンビネーション網や多槽円網あるいは各種ラミネーターなどにより、紙層を２層以上重ね合わせてもよい。なお、圧搾条件はできるだけ弱くして、紙層を極力かさ高にした方が本発明の育苗シートとしては好適なものを得やすい。
【００１９】
本発明に係る育苗方法は、化学処理を受けておらず、かつ実質的にフィブリル化されていないセルロース系繊維を５０〜９０重量％含有するシートであって、厚さが０．８〜５ｍｍ、密度が０．１〜０．５ｇ／ｃｍ³ で、親水化処理が施され、２０℃の蒸留水中に５分間浸漬した後の該シートの繊維配向方向及びこれと直角をなす方向について測定して両者の平均を求めた湿潤引張強度（ＪＩＳＰ−８１１３に基づく測定）及び湿潤裂断長（ＪＩＳＰ−８１１３に基づく測定）のそれぞれは該湿潤引張強度が０．２〜１．０ｋｇ／１５ｍｍ幅で、該湿潤裂断長が０．０２〜０．１ｋｍであるシートを育苗箱に敷き、該シートの上に培土を床土として入れるかもしくは合成培地を置き灌水した後に播種し、覆土し、出芽、緑化し、乳苗段階あるいは稚苗段階において本田に移植するものである。
【００２０】
培土としては、市販の土壌系資材あるいは、減菌した土壌に肥料を配合し、ＰＨ調整して農家が自前で調整した培土材等の通常の育苗で使用される培土資材を使用することができる。
床土量は通常の培土のみを用いる場合に比べ２０〜４０％程度少なくてよい。すなわち、本発明に係る育苗方法では、本発明に係る厚さ０．８〜５ｍｍの育苗シートを下敷とするため、該育苗シートも床土の一部を構成することになり、該育苗シートの上に入れる床土量は通常より２０〜４０％削減できる。
【００２１】
また、本発明に係る肥料を配合していない育苗シートを下敷にして、市販の土壌系資材を通常の場合より２０〜４０％程度少ない量入れて床土とした場合でも問題なく育苗できるが、肥料不足が心配される場合は、育苗シートに所要量の肥料を含有せしめるか、床土の肥料量を所望量増加せしめるかあるいは追肥するなどすればよい。
灌水は下敷した育苗シートが十分に湿潤するよう十分に（育苗箱当り約１リットル）与えるのが望ましい。
播種量は育苗箱当り、稚苗育苗の場合１６０〜１８０ｇ（乾籾）、乳苗育苗の場合２００〜２５０ｇ（乾籾）とするのが望ましい。
覆土、出芽、緑化は常法によればよく、乳苗育苗の場合は５〜７日の育苗期間で、また、稚苗育苗の場合は約３週間の育苗期間で本田への移植ができる。
本田への移植も常法に従えばよい。
【００２２】
【作用】
本発明の育苗シートの特徴は、根の貫通適性と田植機装着時のマット補強という今まで両立が困難であった機能を併せ持たせることができた点にある。
本発明の育苗シートの、根の貫通適性とマット補強力の発現機構の詳細については未だ不明であるが、以下において、本発明者が考察している内容を記す。
まず、根の貫通適性の発現について考察する。本発明の育苗シートは、化学処理を受けておらず、かつ実質的にフィブリル化されていないセルロース系繊維を高含有しているのでシートを構成する繊維同志の繊維間結合はかなり弱い。加えて、本発明の育苗シートは密度が０．１〜０．５ｇ／ｃｍ³ と非常にかさ高で、かつ親水化処理が施されている。従って、育苗箱に本発明に係る育苗シートを敷き、該育苗シートの上に培土を床土として入れた後に十分に灌水した場合、この灌水は培土を通過して育苗シートに到達すると速やかに育苗シートに吸収される。
【００２３】
その結果、育苗シートは十分に湿潤し、保水するとともにその強度は一段と低下する。本発明の育苗シートの湿潤裂断長は０．０２〜０．１ｋｍであり、これは通常の木材パルプによるシートの最も弱いレベルのものと比べてもさらにその数分の１から１／１０程度ときわめて弱い強度である。このように、湿潤時にきわめて強度が低下する。すなわち、繊維間結合がきわめて弱くなるため、培土層を進んできた根は０．８〜５ｍｍ厚の本発明に係る育苗シート中の繊維間結合を押し分けて食い込み、貫通することができる。
【００２４】
つぎに、マット補強力の発現について考察する。
上述したように、本発明の育苗シートの湿潤裂断長はきわめて弱く、このために根が貫通できるのであるが、本発明の育苗シートは０．８〜５ｍｍの厚さを有するのでシートの湿潤引張強度は０．２〜１．０ｋｇ／１５ｍｍ幅である。
この０．２〜１．０ｋｇ／１５ｍｍ幅という湿潤引張強度についてさらに考察する。
比較のために、ここで市販の床土の下敷用育苗シートと床土代替用合成培地マットの強度について述べる。後述するように（比較例７、８）、たとえば、市販の床土の下敷用の高吸水性樹脂担持パルプ系育苗シートについて見ると、常態での引張強度は０．４４４ｋｇ／１５ｍｍ幅であり、２０℃蒸留水５分浸漬引張強度はシートがくずれてしまって測定不能であり事実上強度なしである。従って、実際に床土の下敷として使用し、通常の育苗条件で湿潤している状態ではシート強度がほとんどなくなりマット補強力はないものと考えられる。
【００２５】
また、市販の厚さ１８ｍｍの無機繊維系合成培地マットについて同様にシート強度を測定すると、常態での引張強度は０．２０４ｋｇ／１５ｍｍ幅であり、２０℃蒸留水５分浸漬後の引張強度は０．０８８ｋｇ／１５ｍｍ幅である。
従って、本発明の育苗シートの２０℃蒸留水５分浸漬後の引張強度０．２〜１．０ｋｇ／１５ｍｍ幅は厚さ１８ｍｍもある無機繊維系合成培地マットのそれの２．３〜１１．４倍も強いのである。よって、この優れた湿潤引張強度により、本発明の育苗シートに固有なマット補強力が発現し、たとえ根張りが少なく、マット形成が不良でも、本発明に係る育苗マットが下支えになってマットを補強するため、支障なく田植機に装着でき、また、乳苗段階においても全く支障なく田植機に装着できるというきわめて有益な特性が発現するのである。
【００２６】
【実施例】
次に、本発明を以下の実施例に基づいてさらに具体的に説明する。
本実施例中各項目の測定は次の方法によった。
▲１▼ シートの厚さ：ＪＩＳＰ−８１１８
▲２▼ シートの密度：ＪＩＳＰ−８１１８
▲３▼ シートの引張強度：ＪＩＳＰ−８１１３（ただし、繊維配向方向とこれと直角をなす方向について測定し、両者の平均を求めた。）
▲４▼ シートの裂断長：上記▲１▼シートの厚さ、▲２▼シートの密度及び▲３▼シートの引張強度より

で求めた。
▲５▼ シートの湿潤引張強度：２０℃蒸留水５分浸漬後にＪＩＳＰ−８１１３によって測定した（ただし、繊維配向方向及びこれと直角をなす方向について測定し、両者の平均を求めた。）。
▲６▼ シートの湿潤裂断長：上記▲１▼シートの厚さ、▲２▼シートの密度及び▲５▼シートの湿潤引張強度より

で求めた。
【００２７】
▲７▼ 根の貫通性１、乳苗時マットの田植機装着作業性１、稚苗時マットの田植機装着作業性１：水稲用育苗箱中に２５ｃｍ×２０ｃｍの面積となるように木枠で囲いを設け、該囲いの中にシートを敷き、該シートの上に市販の培土を床土として入れ十分に灌水した後、水稲催芽籾６５ｇを播種し、次いで０．３リットルの覆土を行い、常法に順じて出芽、緑化し、根上りの発生状況を観察するとともに、シート裏面からの根の貫通状況を観察した。また、乳苗まで成育した時点及び稚苗まで成育した時点で枠よりマットを取り上げ田植機への装着作業性を調べた。
▲８▼ 根の貫通性２、乳苗時マットの田植機装着作業性２、稚苗時マットの田植機装着作業性２、田植適性：５７ｃｍ×２７．５ｃｍに断裁したシートを水稲用育苗箱に敷き、該シートの上に市販の培土を床土として入れ、十分に灌水した後、水稲催芽籾２００ｇを播種し、次いで１リットルの覆土を行い、常法により出芽、緑化し、根上りの発生状況を観察するとともに、シート裏面からの根の貫通状況を観察した。また、乳苗まで成育した時点及び稚苗まで成育した時点で育苗箱からマットを取り上げ田植機への装着作業性を調べるとともに通常の田植機により本田への移植を行い、田植適性を評価した。
【００２８】
なお、根の貫通性１、根の貫通性２、乳苗時マットの田植機装着作業性１、乳苗時マットの田植機装着作業性２、稚苗時マットの田植機装着作業性１、稚苗時マットの田植機装着作業性２及び田植適性の評価は次に示す評価基準に基づいて行った。
（ア）根の貫通性１、根の貫通性２
◎ ：ほとんど根上りの発生がなく、かつ局所的な根上りも見られない。（平均的根上り発生率≒０％）
○〜◎：ほとんど根上りの発生がないが、わずかに局所的な根上りが見られる。（平均的根上り発生率５％未満）
○ ：ほとんど根上りの発生がないが、局所的な根上りがある。（平均的根上り発生率５％以上１０％未満）
× ：部分的に根の食い込みが認められるが全体に根上りが多発し不可。
【００２９】
（イ）乳苗時マットの田植機装着作業性１、乳苗時マットの田植機装着作業性２
◎ ：下敷シートの支えにより、マットの保形性が確保され、形くずれ等生じずに田植機への装着等を行える。
○ ：下敷シートの支えにより、マットの保形性がかなり確保され、ほとんど形くずれ等生じずに田植機への装着等を行える。
△ ：下敷シートの支えにより、マットの保形性がある程度はあるもののていねいに扱わないと形くずれすることがあり、田植機への装着作業は慎重に行わねばならない。
× ：下敷シートによる補強は不十分で、形くずれしやすく下敷シートそのものも破断しやすいため、田植機への装着作業は熟練者でもやりにくい。
×× ：マットとしての保形性は、ほとんどなく、取り上げようとするとくずれてしまうため、田植機への装着は困難である。
【００３０】
（ウ）稚苗時マットの田植機装着作業性１、稚苗時マットの田植機装着作業性２
◎ ：マットがしっかりしており、かつ下敷シートによるマット補強効果により図１のようにマットを片手で持ち上げたり、あるいは図２のようにマットを巻いても破断や形くずれ等を生じない。従ってきわめて効率的かつ安心して田植機への装着等の作業を行うことができる。
○ ：マットはかなりしっかりしており、かつ下敷シートによるマット補強効果により図１のようにマットを片手で持ち上げたり、あるいは図２のようにマットを巻いても破断や形くずれ等をほとんど生じない。従ってかなり効率的かつ安心して田植機への装着等の作業を行うことができる。
△ ：マットはかなりしっかりしており、ていねいに扱えばほとんど形くずれ等を生じないが、下敷シートの支えがないか、あっても下敷シートの強度が弱く、第１図のようにマットを片手で持ち上げたり、あるいは第２図のようにマットを巻いた場合には、破断や形くずれ等を生じやすい。従って田植機への装着等の作業におけるマットの扱いは慎重にやらねばならない。
（エ）田植適性
◎ ：欠株の発生も少なく田植機上でのマットの滑り性も良好で問題なく田植作業を進めることができる。
【００３１】
実施例１
化学処理を受けておらず、かつ実質的にフィブリル化されていない木材繊維として乾式木材粉砕物を用い、該木材繊維と新聞古紙を離解機にて混合離解して得た重量比で該木材繊維：新聞古紙＝７０：３０のセルロース系繊維分散液の所定量を取り、これにスルホン酸変性ポリビニルアルコール系親水化剤をセルロース系繊維重量に対して固形分で２．５重量％、シリコン系親水化剤をセルロース系繊維重量に対して固形分で０．５重量％添加し、撹拌機にて十分に分散混合して親水化処理した後、角型手抄機にて手抄を行いシートＡを得た。
シートＡについて、厚さ、密度、引張強度、裂断長、湿潤引張強度、湿潤裂断長、根の貫通性１、乳苗時マットの田植機装着作業性１、及び稚苗時マットの田植機装着作業性１をそれぞれ測定し、その結果を表１に示した。なお床土量は通常の培土のみの場合より約３０％少ない０．７リットルとした。
【００３２】
実施例２
実施例１において、スルホン酸変性ポリビニルアルコール系親水化剤を添加せず、シリコン系親水化剤の添加量をセルロース系繊維重量に対し固形分で０．４重量％とした以外は実施例１と同様にしてシートＢを得た。
シートＢについて、厚さ、密度、引張強度、裂断長、湿潤引張強度、湿潤裂断長、根の貫通性１、乳苗時マットの田植機装着作業性１、及び稚苗時マットの田植機装着作業性１をそれぞれ測定し、その結果を表１に示した。
【００３３】
実施例３
実施例１において、スルホン酸変性ポリビニルアルコール系親水化剤の添加量をセルロース系繊維重量に対し固形分で０．５重量％、シリコン系親水化剤の添加量をセルロース系繊維重量に対し固形分で０．１重量％とした以外は実施例１と同様にしてシートＣを得た。
シートＣについて、厚さ、密度、引張強度、裂断長、湿潤引張強度、湿潤裂断長、根の貫通性１、乳苗時マットの田植機装着作業性１、及び稚苗時マットの田植機装着作業性１をそれぞれ測定し、その結果を表１に示した。
【００３４】
実施例４
実施例１において、セルロース系繊維分散液中の化学処理を受けておらず、かつ実質的にフィブリル化されていない木材繊維と新聞古紙の比率を重量比で該木材繊維：新聞古紙＝８５：１５とした以外は実施例１と同様にしてシートＤを得た。
シートＤについて、厚さ、密度、引張強度、裂断長、湿潤引張強度、湿潤裂断長、根の貫通性１、乳苗時マットの田植機装着作業性１、及び稚苗時マットの田植機装着作業性１をそれぞれ測定し、その結果を表１に示した。ただし床土量は通常の培土のみの場合より約４０％少ない０．６リットルとした。
【００３５】
実施例５
実施例２において、セルロース系繊維分散液中の化学処理を受けておらず、かつ実質的にフィブリル化されていない木材繊維と新聞古紙の比率を重量比で該木材繊維：新聞古紙＝６０：４０とした以外は実施例２と同様にしてシートＥを得た。
シートＥについて、厚さ、密度、引張強度、裂断長、湿潤引張強度、湿潤裂断長、根の貫通性１、乳苗時マットの田植機装着作業性１、及び稚苗時マットの田植機装着作業性１をそれぞれ測定し、その結果を表１に示した。ただし床土量は通常の培土のみの場合より約２０％少ない０．８リットルとした。
【００３６】
実施例６
実施例１において、親水化処理後に、さらに環状窒素化合物系防カビ剤をセルロース系繊維重量に対し固形分で６０ｐｐｍ、水に難溶性で粉体状の緩効性肥料（窒素含有率３０重量％である。以下において同じ。）をセルロース系繊維重量に対し固形分で２．０重量％添加し、十分に撹拌混合した以外は実施例１と同様にしてシートＦを得た。
シートＦについて、厚さ、密度、引張強度、裂断長、湿潤引張強度、湿潤裂断長、根の貫通性１、乳苗時マットの田植機装着作業性１、及び稚苗時マットの田植機装着作業性１をそれぞれ測定し、その結果を表１に示した。
【００３７】
実施例７
実施例５において、シリコン系親水化剤の添加量をセルロース系繊維重量に対し固形分で０．２重量％とした以外は実施例５と同様にしてシートＧを得た。
シートＧについて、厚さ、密度、引張強度、裂断長、湿潤引張強度、湿潤裂断長、根の貫通性１、乳苗時マットの田植機装着作業性１、及び稚苗時マットの田植機装着作業性１をそれぞれ測定し、その結果を表１に示した。
【００３８】
比較例１
実施例１において、スルホン酸変性ポリビニルアルコール系親水化剤とシリコン系親水化剤を添加しない以外は実施例１と同様にしてシートＨを得た。
シートＨについて、厚さ、密度、引張強度、裂断長、湿潤引張強度、湿潤裂断長、根の貫通性１、乳苗時マットの田植機装着作業性１、及び稚苗時マットの田植機装着作業性１をそれぞれ測定し、その結果を表１に示した。
【００３９】
比較例２
実施例１において、セルロース系繊維分散液中の化学処理を受けておらず、かつ実質的にフィブリル化されていない木材繊維と新聞古紙の比率を重量比で該木材繊維：新聞古紙＝４０：６０とした以外は実施例１と同様にしてシートＩを得た。
シートＩについて、厚さ、密度、引張強度、裂断長、湿潤引張強度、湿潤裂断長、根の貫通性１、乳苗時マットの田植機装着作業性１、及び稚苗時マットの田植機装着作業性１をそれぞれ測定し、その結果を表１に示した。
【００４０】
比較例３
実施例１において、シート厚さを厚くし本発明の範囲外とした以外は実施例１と同様にしてシートＪを得た。
シートＪについて、厚さ、密度、引張強度、裂断長、湿潤引張強度、湿潤裂断長、根の貫通性１、乳苗時マットの田植機装着作業性１、及び稚苗時マットの田植機装着作業性１をそれぞれ測定し、その結果を表１に示した。ただし床土量は通常の培土のみの場合より約４０％少ない０．６リットルとした。
【００４１】
比較例４
実施例１において、シート厚さを薄くし本発明の範囲外とした以外は実施例１と同様にしてシートＫを得た。
シートＫについて、厚さ、密度、引張強度、裂断長、湿潤引張強度、湿潤裂断長、根の貫通性１、乳苗時マットの田植機装着作業性１、及び稚苗時マットの田植機装着作業性１をそれぞれ測定し、その結果を表１に示した。ただし床土量は通常の培土のみの場合より約２０％少ない０．８リットルとした。
【００４２】
実施例８
化学処理を受けておらず、かつ実質的にフィブリル化されていない木材繊維として乾式木材粉砕物を用い、該木材繊維と新聞古紙をパルパーにて混合離解し、重量比で該木材繊維：新聞古紙＝７０：３０のセルロース系繊維分散原料を得、次いで、スルホン酸変性ポリビニルアルコール系親水化剤をセルロース系繊維重量に対し固形分で２．５％、シリコン系親水化剤をセルロース系繊維重量に対し固形分で０．５重量％添加し、十分に撹拌混合して親水化処理した後、長網抄造網上に供給し紙層形成せしめ、ワインドアップロールにて所定厚さになるまで巻き付けた後、切断し、圧搾、乾燥しシートＬを得た。
シートＬについて、厚さ、密度、引張強度、裂断長、湿潤引張強度、湿潤裂断長、根の貫通性２、乳苗時マットの田植機装着作業性２、稚苗時マットの田植機装着作業性２及び田植適性をそれぞれ測定し、その結果を表２に示した。なお、床土量は、通常の培土のみの場合より約３０％少ない２．２リットルとした。
【００４３】
実施例９
実施例８において、セルロース系繊維分散原料中の化学処理を受けておらず、かつ実質的にフィブリル化されていない木材繊維と新聞古紙の重量比を該木材繊維：新聞古紙＝８０：２０とした以外は実施例８と同様にしてシートＭを得た。シートＭについて、厚さ、密度、引張強度、裂断長、湿潤引張強度、湿潤裂断長、根の貫通性２、乳苗時マットの田植機装着作業性２、稚苗時マットの田植機装着作業性２及び田植適性をそれぞれ測定し、その結果を表２に示した。床土量は、通常の培土のみの場合より約４０％少ない１．９リットルとした。
【００４４】
実施例１０
実施例８において、セルロース系繊維分散原料中の化学処理を受けておらず、かつ実質的にフィブリル化されていない木材繊維と新聞古紙の重量比を該木材繊維：新聞古紙＝６０：４０とした以外は実施例８と同様にしてシートＮを得た。シートＮについて、厚さ、密度、引張強度、裂断長、湿潤引張強度、湿潤裂断長、根の貫通性２、乳苗時マットの田植機装着作業性２、稚苗時マットの田植機装着作業性２及び田植適性をそれぞれ測定し、その結果を表２に示した。床土量は、通常の培土のみの場合より約２０％少ない２．５リットルとした。
【００４５】
実施例１１
実施例８において、スルホン酸変性ポリビニルアルコール系親水化剤の添加量をセルロース系繊維重量に対し１．０重量％、シリコン系親水化剤の添加量をセルロース系繊維重量に対し０．２重量％とし、親水化処理後に、さらに環状窒素化合物系カビ剤をセルロース系繊維重量に対し固形分で６０ｐｐｍ、水に難溶性で粉体状の緩効性肥料をセルロース系繊維重量に対し固形分で２．０重量％添加し、十分に撹拌混合した以外は実施例８と同様にしてシートＯを得た。
シートＯについて、厚さ、密度、引張強度、裂断長、湿潤引張強度、湿潤裂断長、根の貫通性２、乳苗時マットの田植機装着作業性２、稚苗時マットの田植機装着作業性２及び田植適性をそれぞれ測定し、その結果を表２に示した。
【００４６】
実施例１２
実施例１１で得たシートＯを育苗箱に敷き、この上に市販の床土代替用の無機質合成培地マット（後述の比較例８で用いたものと同じもの）を置き、十分に灌水した後、該合成培地マットに直接播種し、根の貫通性２、乳苗時マットの田植機装着作業性２、稚苗時マットの田植機装着作業性２及び田植適性をそれぞれ測定し、その結果を表２に示した。但し、この場合、無機質合成培地マットの厚さを１５ｍｍに調整して用いた。
【００４７】
比較例５
通常の培土のみを用い、補強シートを使わなかった場合の根の貫通性２、乳苗マットの田植機装着作業性２、稚苗時マットの田植機装着作業性２、及び田植適性をそれぞれ測定し、その結果を表２に示した。なお、床土量は３リットルとした。
【００４８】
比較例６
新聞紙について、厚さ、密度、引張強度、裂断長、湿潤引張強度、湿潤裂断長、根の貫通性２、乳苗時マットの田植機装着作業性２、稚苗時マットの田植機装着作業性２及び田植適性をそれぞれ測定し、その結果を表２に示した。床土量は３リットルとした。
【００４９】
比較例７
市販の床土の下敷用の高吸水性樹脂担持パルプ系育苗シートについて厚さ、密度、引張強度、裂断長、湿潤引張強度、湿潤裂断長、根の貫通性２、乳苗時マットの田植機装着作業性２、稚苗時マットの田植機装着作業性２及び田植適性をそれぞれ測定し、その結果を表２に示した。床土量は、通常の培土のみの場合より約２０％少ない２．５リットルとした。
【００５０】
比較例８
市販の床土代替用の無機繊維系合成培地マットについて、厚さ、密度、引張強度、裂断長、湿潤引張強度、湿潤裂断長、根の貫通性２、乳苗時マットの田植機装着作業性２、稚苗時マットの田植機装着作業性２及び田植適性をそれぞれ測定し、その結果を表２に示した。ただし、この場合床土なしで無機繊維系合成培地マットに十分灌水した後、該合成培地マットに直接播種した。
【００５１】
【発明の効果】
本発明の育苗シートは、上記した実施例１〜１２、比較例１〜８、表１及び表２からわかるように、化学処理を受けておらず、かつ実質的にフィブリル化されていないセルロース系繊維を高含有せしめ、厚さ及び密度を所定範囲とし、さらに親水化処理を施し、所定の湿潤条件時の湿潤引張強度と湿潤裂断長を特定範囲とした結果、優れた植物育成適性と十分な強度を併せ持ち、育苗作業の作業性改善及び効率向上を図ることのできる育苗シートを得ることができた。
【００５２】
本発明の育苗シートの特に優れている点は、根の貫通性と田植機装着作業時のマット補強という今まで両立が困難であった機能を兼備しているところである。すなわち、本発明の育苗方法によれば、田植機への装着時に、たとえ根張りが少なくマット形成が不良でも、本発明の育苗シートのマット補強効果により支障なく作業を行うことができるとともに、本発明の育苗シートが床土の一部として機能するため、床土量を通常の培土のみを使用する場合に比べ２０〜４０％程度削減することができる。
【００５３】
加えて、通常の培土では困難であり、また無機繊維系合成培地等を用いても難点のあった乳苗段階での田植機への装着も問題なく可能となり、乳苗育苗による・育苗期間の短縮（稚苗育苗が約３週間かかるのに対し、乳苗育苗は５〜７日と約１／３ですむ。）・播種量の増量（稚苗育苗が育苗箱当り乾籾で１６０〜１８０ｇであるのに対し、乳苗育苗では２００〜２５０ｇと２０〜５０％増量できる。）・本田単位面積当りの育苗箱使用数の削減・育苗センターのローテーションの効率化などの利点をあますところなく享受できる。
【図面の簡単な説明】
【図１】本発明の育苗シートを用い、本発明の育苗方法により得たマットを片手で持ち上げた状態を示す描写図である。
【図２】本発明の育苗シートを用い、本発明の育苗方法により得たマットを本田への移植作業の効率化を図るべく巻いた状態を示す描写図である。
【符号の説明】
１．育苗シート
２．床土あるいは合成培地マット
３．苗
【表１】

【表２】

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a seedling sheet mainly used for raising rice seedlings and a seedling method using the seedling sheet. More specifically, the present invention has both excellent plant growth aptitude and sufficient strength, and aims to improve seedling work and improve efficiency. The present invention relates to a seedling sheet that can be used and a rational and efficient seedling method using the seedling sheet.
[0002]
[Prior art]
Currently, paddy rice seedling is usually carried out by putting the soil into the seedling box as floor soil, watering, sowing, covering, budding, greening, and transplanting to Honda at the seedling stage by rice transplanter. It is.
[0003]
[Problems to be solved by the invention]
The most troublesome of the series of seedling work is the work of picking up a mat with seedlings from the seedling box and mounting it on a rice transplanter. If the rooting is insufficient and the formation of the mat is poor, the mat will be deformed or scattered when the mat is picked up, making the operation difficult.
[0004]
Possible causes of mat formation failure include poor soil quality, improper management of seedling conditions such as irrigation amount and nursery room temperature, and climatic conditions such as temperature and amount of sunlight. Another reason is that there are many cases where general farming conditions cannot be managed because there are many part-time farmers and labor shortages.
On the other hand, since a large amount of seedlings are raised at the seedling center, seedling facilities are generally provided, which is advantageous in managing the seedling conditions. However, since the seedlings of a large number of farmers are substituted, in the unlikely event that a mat formation failure occurs, it becomes a problem of responsibility and the situation is serious. In addition, in order to handle a large amount of seedlings at the seedling center, it is necessary to start raising seedlings from the time when the temperature and the amount of sunlight are not necessarily suitable for the convenience of planning and handling rotations. It is necessary to increase the efficiency of seedling raising by shortening the period and speeding up the seedling rotation, thereby improving the productivity.
[0005]
Breeding seedlings can shorten the growing period by about 1/3 compared with young seedlings. (2) The seeding amount can be increased by about 20 to 50%. (3) The number of seedling boxes per unit area of Honda is small. (4) Raise seedling rotation. (5) As a result, the cost can be reduced. It has the following advantages.
However, raising seedlings using cultivated soil as floor soil has little rooting at the nursery seedling stage, and the mat formation is insufficient and cannot be mounted on the rice transplanter. In recent years, various fiber-based or inorganic fiber-based synthetic medium mats have been developed. Such synthetic medium mats are manufactured by a dry method using a very small amount of binder in order to improve root bite and prevent root-up. Most of them are low in density and remarkably weak in strength, and there is no one that can fully exhibit the function of mat reinforcement. Some of them are used for raising seedlings, but the mat reinforcement is not sufficient, and the workability of attaching rice transplanters to raising seedlings is not always good.
[0006]
On the other hand, in the case of wet papermaking, generally, the interfiber bonding tends to be strong, and it has hardly been obtained because it is difficult to obtain a mat that can penetrate the roots. It has been proposed that the penetration ability of the roots can be ensured by dispersing the superabsorbent resin evenly in the gaps so that the highly water-absorbent resin absorbs and expands during water absorption and breaks or relaxes the bond between fibers.
However, papermaking with a raw material slurry containing a highly water-absorbing resin in a water-absorbed and expanded state may cause problems in the manufacturing process, such as the water-absorbing and highly water-absorbing resin easily adhering to the papermaking net. The sheet at the time becomes very weak, and in some cases the mat reinforcement is insufficient. In addition, for users accustomed to seedling methods that use cultivation soil as floor soil, raising seedlings using synthetic cultivation mats that do not use floor soil is technologically leap and may be difficult to accept. The prevalence of raising seedlings with medium mats is very low at present.
[0007]
Therefore, there has been a strong demand for the emergence of seedling materials or seedling methods that can eliminate the troubles when mounting on rice transplanters due to poor mat formation in seedling raising seedlings, and that can cope with nurturing seedlings with confidence.
The present invention was made to solve the above-mentioned problems, has both excellent plant growth aptitude and sufficient strength, enables mounting on a rice transplanter even if the mat formation is poor, and also supports nursling seedlings An object of the present invention is to provide a seedling sheet capable of improving workability and efficiency in seedling work, and a rational and efficient seedling method using the seedling sheet.
[0008]
[Means for Solving the Problems]
The present inventor considers in order to solve the above problems most rationally and effectively, and in particular, the advantage of wet papermaking with cellulosic fibers that can form a sheet by bonding force between fibers (hydrogen bonding) without using a binder. From the viewpoint of how to weaken the bond between the fibers as much as possible so that the roots can penetrate through the roots of the cellulosic fibers that have not undergone chemical treatment and are not substantially fibrillated We proceeded with the examination.
Such cellulosic fibers have little or no fiber-to-fiber bond strength, and are very weak in fiber-to-fiber bond strength. It must be applied to the papermaking after the quality or beating is applied to give a certain degree of interfiber bonding force.
[0009]
As a result, the present inventor has deliberately studied a technique for making paper using materials that are unsuitable for such paper making as much as possible. A sheet containing a high amount of non-fibrillated cellulosic fibers is formed, the thickness and density are set within the specified ranges, and the surface is further hydrophilized, and the wet tensile strength and wet tear length under the specified wet conditions are within the specified ranges. Therefore, when used as an underlay for seedlings, the ability to penetrate the roots and the contradictory functions of mat reinforcement can be achieved at the same time, that is, the root penetration is good if the seedlings are grown in this way. At the same time, when installed in a rice transplanter, even if there is little rooting and the mat formation is poor, it is possible to work without hindrance by the reinforcement effect of the underlay sheet, and in the seedling stage That the mounting may also tighten if possible to have completed the locate the present invention.
[0010]
That is, the seedling-raising sheet according to the present invention is a hydrophilized sheet containing 50 to 90% by weight of a cellulose fiber that has not undergone chemical treatment and is not substantially fibrillated, and the thickness of the sheet. 0.8-5mm, density 0.1-0.5g / cm ^Three The wet tensile strength obtained by measuring the fiber orientation direction of the sheet after being immersed in distilled water at 20 ° C. for 5 minutes and the direction perpendicular to the fiber orientation (measurement based on JIS P-8113) And wet tear length (measured based on JIS P-8113) each having a wet tensile strength of 0.2 to 1.0 kg / 15 mm width and a wet tear length of 0.02 to 0.1 km It is.
[0011]
The seedling sheet according to the present invention must contain 50 to 90% by weight, preferably 60 to 80% by weight, of a cellulosic fiber that has not undergone chemical treatment and is not substantially fibrillated. When the content is less than 50% by weight, the penetration of the roots is hindered and the roots are easily generated. On the other hand, when it exceeds 90% by weight, the papermaking property is deteriorated and the strength of the obtained sheet is too weak to obtain a sufficient mat reinforcing effect.
Cellulosic fibers that have not been subjected to chemical treatment and are not substantially fibrillated include various types of wood fibers such as pulverized wood, wood wool, wood flour, and wood fiber made from wood waste and wood fragments. Wood pulp that has not been subjected to chemical treatment such as mechanical pulp can be used.
[0012]
In addition, in the seedling sheet of the present invention, in order to obtain a predetermined sheet strength, a cellulosic fiber other than the cellulosic fiber not subjected to the above-described chemical treatment and substantially not fibrillated is used in combination. Is desirable. As the cellulose fiber, one or two or more kinds selected from wood pulp such as coniferous or hardwood chemical pulp, semi-chemical pulp, various waste paper, bagasse, straw, linter, etc. are used in combination. be able to. The content of such cellulosic fibers in the seedling sheet according to the present invention is preferably 5 to 40% by weight. If the content is less than 5% by weight, a predetermined sheet strength may not be obtained. On the other hand, if it exceeds 40% by weight, the sheet strength becomes too strong, and root penetration may be hindered and root up may occur.
[0013]
The thickness of the seedling sheet of the present invention should be 0.8 to 5 mm, preferably 1.5 to 3 mm. If the thickness is less than 1 mm, the strength is insufficient and a sufficient mat reinforcing effect cannot be obtained. On the other hand, when it exceeds 5 mm, the penetrability of the roots is hindered and the roots are likely to rise.
The density of the seedling sheet of the present invention is 0.1 to 0.5 g / cm. ^Three Preferably 0.15-0.4 g / cm ^Three Must. The density is 0.1 g / cm ^Three If it is less than 1, the sheet strength is too weak to obtain a sufficient effect. Conversely, 0.5 g / cm ^Three If it exceeds, the root bite deteriorates, and it tends to cause uprooting.
[0014]
The seedling sheet of the present invention must be hydrophilized. Since the seedling sheet of the present invention has not been subjected to chemical treatment and contains a high amount of cellulose fibers that are not substantially fibrillated, the water absorption necessary as a seedling sheet is ensured unless a hydrophilic treatment is performed. Can not do it.
Hydrophilization treatment is not particularly limited, and various surfactants such as sulfonic acid type, carboxylic acid type, phosphoric ester type, sulfuric acid ester type, quaternary ammonium salt type or higher alcohols, polyhydric alcohols, A hydrophilicity imparting agent such as a silicon hydrophilizing agent or a PVA hydrophilizing agent may be internally added, impregnated or coated.
Further, the amount of the hydrophilicity-imparting agent is not particularly limited, but it is important that the amount is such that the wet tensile strength and the wet tear length of the sheet are within the ranges specified in the present invention. There is a need.
[0015]
After dipping the seedling sheet of the present invention in distilled water at 20 ° C. for 5 minutes, the wet tensile strength measured based on JIS P-8113 is 0.2 to 1 on the average in the fiber orientation direction and the direction perpendicular thereto. 0.0kg / 15mm width, preferably 0.3-0.7kg / 15mm width. The wet tear length determined from the wet tensile strength should be 0.02 to 0.1 km, preferably 0.03 to 0.07 km. When the above-mentioned wet tensile strength is less than 0.2 kg / 15 mm width or the above-mentioned wet tear length is less than 0.02 km, a sufficient mat reinforcing effect cannot be obtained, and the seedlings are raised when the mat is taken up when there is little rooting. It is easy to cause troubles such as the sheet breaking. On the other hand, when the above-described wet tensile strength exceeds 1.0 kg / 15 mm width or the above-mentioned wet tearing length exceeds 0.1 km, root biting deteriorates and root upping tends to occur.
[0016]
The seedling sheet of the present invention is not subjected to chemical treatment as described above, and has a high content of cellulosic fibers that are not substantially fibrillated, subjected to hydrophilic treatment, and has a thickness, density, and wet tension. The strength and wet tearing length are within the prescribed ranges, so that both the ability to penetrate the root and the mat reinforcing force are combined. However, inorganic fillers such as clay and talc, rock wool fibers, glass fibers, ceramic fibers By blending inorganic fibers such as these, it is possible to further weaken the bond between fibers and improve the penetrability of the roots.
Also, if necessary, binders such as various synthetic resin latices may be blended, but in this case, it is natural that the amount added should be kept to a very small amount so as not to inhibit root penetration. .
Furthermore, if necessary, nitrogen fertilizers such as ammonium sulfate, ammonium sulfate and urea, potassium fertilizers such as potassium sulfate and potassium chloride, or phosphate fertilizers such as superphosphate lime and ammonium phosphate, etc., sulfuric acid and citric acid PH adjusters such as humic acid, nitrohumic acid, peat moss, and fungicides may be added. In addition, when blending fertilizer by internal addition in wet papermaking, it is more effective to use a powdery slow-acting fertilizer that is difficult to dissolve in water.
[0017]
In order to produce the seedling sheet of the present invention, dry molding may be used, but wet papermaking is more preferable. In the case of dry molding, in order to obtain a sheet strength sufficient to exhibit a sufficient mat reinforcing effect, it is indispensable to add an appropriate amount of various types of binders such as various synthetic resin latexes. It may be quite difficult to achieve both. On the other hand, in the case of wet papermaking, it is sufficient to exhibit a sufficient mat reinforcing effect by inter-fiber bonding by hydrogen bonding between cellulosic fibers formed in the papermaking process without necessarily using the above-mentioned binders. Since the sheet strength can be obtained, both the ability to penetrate the root and the mat reinforcing force can be achieved.
[0018]
Here, the case where the seedling raising sheet | seat of this invention is manufactured by wet papermaking is demonstrated further. That is, in order to produce the seedling sheet of the present invention by wet papermaking, a normal slurry is prepared by preparing a raw slurry containing a predetermined amount of cellulose fiber that has not been subjected to chemical treatment and is not substantially fibrillated. It can be made by the law. Then, the above-described various hydrophilicity imparting agents may be internally added to the raw material slurry, or may be subjected to a hydrophilization treatment by impregnation or coating after forming a sheet. In addition, beating treatment may be performed as necessary, but the cellulosic fibers that have not undergone chemical treatment in the raw slurry and are not substantially fibrillated are maintained in this state, and the interfiber bonding force Must be kept in a state where it is difficult to express. Therefore, beating under very weak conditions that do not substantially cause fibrillation or chemical treatment, and treatment of cellulosic fibers that are not substantially fibrillated is a separate route. It is necessary to devise such as using without. For papermaking, the raw material slurry may be supplied onto a papermaking net such as a normal long net, circular net or inclined net, filtered and dehydrated, and then compressed and dried. If necessary, two or more paper layers may be overlapped by various combination nets, multi-tank circular nets, or various laminators. In addition, it is easy to obtain a suitable seedling-raising sheet of the present invention by reducing the pressing conditions as much as possible and making the paper layer as bulky as possible.
[0019]
The seedling raising method according to the present invention is a sheet containing 50 to 90% by weight of a cellulosic fiber that has not undergone chemical treatment and is not substantially fibrillated, and has a thickness of 0.8 to 5 mm, Density is 0.1-0.5g / cm ^Three The wet tensile strength (JIS P) obtained by measuring the fiber orientation direction and the direction perpendicular to the fiber orientation of the sheet after being hydrophilized and immersed in distilled water at 20 ° C. for 5 minutes. -8113) and wet tear length (measurement based on JIS P-8113) each have a wet tensile strength of 0.2 to 1.0 kg / 15 mm width and a wet tear length of 0.02 Place a sheet of 0.1 km in a seedling box and put culture medium on the sheet as floor soil or irrigate after placing synthetic medium on it, sowing, covering, budding, greening, nurturing stage or seedling stage Will be transplanted to Honda.
[0020]
As soil for cultivation, commercially available soil-based materials or soil-cultivated materials that are used for normal seedlings such as soil-grown materials prepared by the farmer by adjusting the pH and adjusting the pH can be used. .
The amount of floor soil may be about 20 to 40% less than when only normal soil is used. That is, in the seedling raising method according to the present invention, since the seedling sheet having a thickness of 0.8 to 5 mm according to the present invention is used as an underlay, the seedling sheet also constitutes a part of the floor soil. The amount of floor soil placed on top can be reduced by 20 to 40% than usual.
[0021]
In addition, the seedling sheet that does not contain the fertilizer according to the present invention is used as an underlay, and even when the soil is put into floor soil by adding about 20 to 40% less than a normal soil-based material, seedling can be raised without problems. If there is a concern about the shortage of fertilizers, the seedling sheet may contain the required amount of fertilizer, the amount of fertilizer in the floor soil may be increased by a desired amount, or additional fertilization may be performed.
It is desirable that irrigation is given sufficiently (about 1 liter per seedling box) so that the underlying seedling sheet is sufficiently wetted.
The seeding amount per seedling box is preferably 160 to 180 g (dry pods) in the case of young seedlings and 200 to 250 g (dry pods) in the case of nursery seedlings.
Covering, budding, and greening may be carried out according to conventional methods. In the case of nurturing seedlings, transplanting to Honda can be performed in a seedling period of 5 to 7 days, and in the case of young seedlings, it can be transplanted in about 3 weeks.
Transplanting into Honda can be done according to conventional methods.
[0022]
[Action]
The seedling sheet of the present invention is characterized in that it has a function that has been difficult to achieve at the same time, such as the ability to penetrate the root and the mat reinforcement when the rice transplanter is mounted.
The details of the root penetration suitability and the mechanism of expression of the mat reinforcing force of the seedling sheet of the present invention are still unclear, but the contents considered by the present inventor will be described below.
First, the expression of root penetration suitability will be considered. Since the seedling sheet of the present invention is not subjected to chemical treatment and contains a high amount of cellulosic fibers that are not substantially fibrillated, the fiber-to-fiber bonds of the fibers constituting the sheet are considerably weak. In addition, the seedling sheet of the present invention has a density of 0.1 to 0.5 g / cm. ^Three It is very bulky and has been hydrophilized. Therefore, when a seedling sheet according to the present invention is laid in a seedling box and the cultivated soil is placed on the seedling sheet and sufficiently irrigated, the irrigation quickly passes through the cultivated soil and reaches the seedling sheet. Absorbed into the sheet.
[0023]
As a result, the seedling sheet becomes sufficiently wet and retains water, and the strength further decreases. The wet tearing length of the seedling sheet of the present invention is 0.02 to 0.1 km, which is about a fraction to 1/10 of the weakest level of a sheet made of ordinary wood pulp. It is very weak strength. Thus, the strength is extremely reduced when wet. That is, since the bond between fibers becomes extremely weak, the roots that have advanced through the cultivation layer can penetrate and penetrate through the bond between fibers in the seedling-growing sheet according to the present invention having a thickness of 0.8 to 5 mm.
[0024]
Next, the expression of the mat reinforcing force will be considered.
As described above, the wet tearing length of the seedling sheet of the present invention is very weak, and thus the root can penetrate. However, the seedling sheet of the present invention has a thickness of 0.8 to 5 mm, so that the sheet wets. The tensile strength is 0.2 to 1.0 kg / 15 mm width.
The wet tensile strength of 0.2 to 1.0 kg / 15 mm width will be further considered.
For comparison, the strength of a commercial seedling sheet for underlaying and a synthetic medium mat for substituting floor soil will be described here. As will be described later (Comparative Examples 7 and 8), for example, when viewing a commercially available superabsorbent resin-supported pulp-based seedling sheet for floor soil, the tensile strength in a normal state is 0.444 kg / 15 mm width, The 20-degree C distilled water immersion tensile strength is not measurable because the sheet collapses and is virtually unstrengthened. Accordingly, it is considered that the sheet strength is almost lost and there is no mat reinforcing force when it is actually used as an underlay for floor soil and is moistened under normal breeding conditions.
[0025]
In addition, when the sheet strength is measured in the same manner for a commercially available inorganic fiber synthetic medium mat having a thickness of 18 mm, the tensile strength in a normal state is 0.204 kg / 15 mm width, and the tensile strength after immersion for 5 minutes at 20 ° C. in distilled water is The width is 0.088 kg / 15 mm.
Accordingly, the tensile strength 0.2-1.0 kg / 15 mm width after immersion of the seedling sheet of the present invention for 5 minutes at 20 ° C. in the water is 2.3-11. It is four times stronger. Therefore, this excellent wet tensile strength expresses a mat reinforcing force unique to the seedling sheet of the present invention, and even if there is little rooting and the mat formation is poor, the seedling mat according to the present invention provides a support for the mat. Because it reinforces it, it can be mounted on a rice transplanter without any trouble, and at the stage of the seedling, it can be mounted on a rice transplanter without any trouble.
[0026]
【Example】
Next, the present invention will be described more specifically based on the following examples.
The measurement of each item in this example was performed according to the following method.
(1) Sheet thickness: JIS P-8118
(2) Sheet density: JIS P-8118
{Circle around (3)} Tensile strength of sheet: JIS P-8113 (however, the fiber orientation direction and the direction perpendicular thereto were measured, and the average of both was determined.)
(4) Sheet tear length: From the above (1) sheet thickness, (2) sheet density, and (3) sheet tensile strength

I asked for it.
(5) Wet tensile strength of sheet: Measured according to JIS P-8113 after immersion in distilled water at 20 ° C. for 5 minutes (however, the fiber orientation direction and the direction perpendicular thereto were measured to determine the average of both).
(6) Wet tear length of sheet: From the above (1) sheet thickness, (2) sheet density, and (5) sheet wet tensile strength

I asked for it.
[0027]
▲ 7 Root penetration 1 、 Rose matting rice transplanter installation workability 1 、 Napling matting rice transplanter installation workability 1 ： A wooden frame so that it has an area of 25cm × 20cm in the paddy rice seedling box After placing a sheet in the enclosure, placing a commercially available soil as a floor soil on the sheet and thoroughly irrigating it, seeding with 65 g of paddy rice germination buds, then covering with 0.3 liters of soil According to the conventional method, budding and greening were observed, and the occurrence of uprooting was observed, and the penetration of roots from the back of the sheet was observed. In addition, the mat was taken out of the frame at the time of growing up to the seedlings and the time of growing up to the young seedlings, and the mounting workability to the rice transplanter was examined.
▲ 8 ▼ Root penetration 2, Rice planter installation workability 2 for maturing seedlings, Rice transplanter installation workability 2 for maturing seedlings, Rice planting suitability: A seedling box for paddy rice that has been cut into 57cm x 27.5cm Lay on the sheet, put a commercially available soil as a floor soil on the sheet, after sufficiently irrigating, seeded with 200 g of paddy rice germination buds, then covered with 1 liter of soil, budding and greening by ordinary methods, generation of uprooting While observing the situation, the penetration of the root from the back of the sheet was observed. Moreover, when mats were grown up to seedlings and when they were grown up to young seedlings, the mats were picked up from the seedling box and examined for workability on the rice transplanter, and transplanted to Honda using a normal rice transplanter to evaluate the suitability of rice transplanting.
[0028]
In addition, root penetrability 1, root penetrability 2, rice seedling machine mounting workability 1 at the time of seedling matting, rice transplanter mounting workability 2 at the time of seedling matting, rice transplanter mounting workability 1 at the time of seedling matting, The evaluation of the rice transplanter mounting workability 2 and the rice planting suitability of the mat for seedlings was performed based on the following evaluation criteria.
(A) Root penetration 1 and root penetration 2
A: Almost no uprooting occurs and no local uprooting is observed. (Average uprooting rate ≒ 0%)
○ to ◎: There is almost no occurrence of rooting, but a slight local rooting is observed. (Average uptake rate of less than 5%)
○: Almost no uprooting occurs, but there is local uprooting. (Average uptake rate of 5% or more and less than 10%)
X: Partial biting of the roots is recognized, but the whole roots frequently occur and is impossible.
[0029]
(I) Rice transplanter mounting workability 1 for maturing seedlings, rice transplanter mounting workability 2 for matting seedlings
◎: The shape retention of the mat is secured by the support of the underlay sheet, so that the mat can be mounted on the rice transplanter without being deformed.
○: The support of the underlay sheet ensures the shape retention of the mat and can be mounted on a rice transplanter with almost no deformation.
Δ: The support of the underlay sheet has a certain shape retaining property of the mat, but may be deformed if not handled carefully, and the mounting work to the rice transplanter must be performed carefully.
×: Reinforcement by the underlay sheet is insufficient, and the underlay sheet itself is easily broken and easily broken, so that it is difficult for even a skilled worker to perform the installation work on the rice transplanter.
XX: There is almost no shape-retaining property as a mat, and it will be broken when trying to pick it up, so it is difficult to mount it on a rice transplanter.
[0030]
(C) Rice transplanter mounting workability 1 for seedling mats, rice transplanter mounting workability 2 for seedling mats
A: The mat is solid, and the mat reinforcement effect by the underlay sheet does not cause breakage or deformation even when the mat is lifted with one hand as shown in FIG. 1 or wound as shown in FIG. Therefore, it is possible to perform operations such as mounting on a rice transplanter with high efficiency and peace of mind.
○: The mat is fairly solid, and the mat reinforcement effect of the underlay sheet hardly lifts or deforms even when the mat is lifted with one hand as shown in FIG. 1 or wound as shown in FIG. . Therefore, it is possible to perform operations such as mounting on a rice transplanter with considerable efficiency and peace of mind.
△: The mat is fairly solid, and if it is handled carefully, it will not be deformed, etc., but there is no support for the underlay sheet, or even if the undersheet is weak, the mat is held in one hand as shown in Fig. 1. 2 or when the mat is wound as shown in FIG. 2, breakage or deformation tends to occur. Therefore, the mat must be handled carefully in the operation such as mounting on the rice transplanter.
(D) Rice transplanting aptitude
◎: There are few outbreaks and the slipperiness of the mat on the rice transplanter is good.
[0031]
Example 1
The wood fiber in a weight ratio obtained by using a dry wood pulverized product as a wood fiber that has not been subjected to chemical treatment and is not substantially fibrillated, and the wood fiber and old newspaper are mixed and disaggregated by a disaggregator. : Waste paper = 70:30 Cellulose fiber dispersion of 70:30, sulfonic acid-modified polyvinyl alcohol hydrophilizing agent is 2.5% by weight in solid content with respect to cellulose fiber weight, silicone hydrophilic After adding 0.5% by weight of a solidifying agent to the weight of the cellulosic fiber, sufficiently dispersing and mixing with a stirrer to make a hydrophilic treatment, the paper is hand-made with a square-type hand machine and sheet A Got.
For sheet A, thickness, density, tensile strength, tearing length, wet tensile strength, wet tearing length, root penetration 1, mater attachment workability 1 for seedling mats, and rice seedlings for seedling mats The machine mounting workability 1 was measured, and the results are shown in Table 1. The amount of floor soil was 0.7 liters, which was about 30% less than the case of normal cultivation alone.
[0032]
Example 2
Example 1 is the same as Example 1 except that the sulfonic acid-modified polyvinyl alcohol-based hydrophilizing agent is not added and the addition amount of the silicon-based hydrophilizing agent is 0.4% by weight in terms of solid content with respect to the cellulose fiber weight. A sheet B was obtained in the same manner.
For sheet B, thickness, density, tensile strength, tear length, wet tensile strength, wet tear length, root penetration 1, mater attachment workability 1 for maturing seedlings, and rice seedling for mating seedlings The machine mounting workability 1 was measured, and the results are shown in Table 1.
[0033]
Example 3
In Example 1, the addition amount of the sulfonic acid-modified polyvinyl alcohol hydrophilizing agent is 0.5% by weight in solid content with respect to the weight of the cellulose fiber, and the addition amount of the silicon hydrophilizing agent is solid content with respect to the weight of the cellulose fiber. A sheet C was obtained in the same manner as in Example 1 except that the content was 0.1 wt%.
For sheet C, thickness, density, tensile strength, tear length, wet tensile strength, wet tear length, root penetration 1, mater attachment workability 1 for seedling mats, and rice seedling for seedling mats The machine mounting workability 1 was measured, and the results are shown in Table 1.
[0034]
Example 4
In Example 1, the weight ratio of wood fiber to newspaper waste paper not subjected to chemical treatment in the cellulosic fiber dispersion and substantially fibrillated was: wood fiber: new waste paper = 85: 15 A sheet D was obtained in the same manner as in Example 1 except that.
For sheet D, thickness, density, tensile strength, tearing length, wet tensile strength, wet tearing length, root penetration 1, mater attachment workability 1 for maturing seedlings, and rice transplanting for mating seedlings The machine mounting workability 1 was measured, and the results are shown in Table 1. However, the amount of floor soil was set to 0.6 liters, which is about 40% less than that in the case of normal cultivation alone.
[0035]
Example 5
In Example 2, the wood fiber: newspaper waste paper = 60: 40 in terms of weight ratio of wood fibers not subjected to chemical treatment in the cellulose fiber dispersion and not substantially fibrillated to wastepaper wastepaper. A sheet E was obtained in the same manner as in Example 2 except that.
For sheet E, thickness, density, tensile strength, tearing length, wet tensile strength, wet tearing length, root penetrability 1, rice seedling machine mounting workability 1 for maturing seedlings, and rice transplanting for mating seedlings The machine mounting workability 1 was measured, and the results are shown in Table 1. However, the amount of floor soil was set to 0.8 liters, which is about 20% less than that of ordinary cultivated soil alone.
[0036]
Example 6
In Example 1, after the hydrophilization treatment, a cyclic nitrogen compound-based fungicide was further added to the cellulose fiber weight in a solid content of 60 ppm, a water-soluble and powdery slow-release fertilizer (nitrogen content 30% by weight) In the following, sheet F was obtained in the same manner as in Example 1 except that 2.0% by weight of the solid content with respect to the weight of the cellulosic fiber was added and the mixture was sufficiently stirred and mixed.
About sheet F, thickness, density, tensile strength, tearing length, wet tensile strength, wet tearing length, root penetrability 1, rice seedling machine mounting workability 1 for maturing seedlings, and rice transplanting for mating seedlings The machine mounting workability 1 was measured, and the results are shown in Table 1.
[0037]
Example 7
In Example 5, a sheet G was obtained in the same manner as in Example 5 except that the addition amount of the silicon-based hydrophilizing agent was 0.2% by weight in terms of solid content with respect to the weight of the cellulose-based fiber.
For sheet G, thickness, density, tensile strength, tearing length, wet tensile strength, wet tearing length, root penetrability 1, rice seedling machine installation workability 1 for maturing seedlings, and rice transplanting for mating seedlings The machine mounting workability 1 was measured, and the results are shown in Table 1.
[0038]
Comparative Example 1
In Example 1, a sheet H was obtained in the same manner as in Example 1 except that the sulfonic acid-modified polyvinyl alcohol hydrophilizing agent and the silicon hydrophilizing agent were not added.
About sheet H, thickness, density, tensile strength, tearing length, wet tensile strength, wet tearing length, root penetrability 1, rice seedling machine mounting workability 1 for maturing seedlings, and rice transplanting for mating seedlings The machine mounting workability 1 was measured, and the results are shown in Table 1.
[0039]
Comparative Example 2
In Example 1, the weight ratio of wood fiber to newspaper waste paper not subjected to chemical treatment in the cellulose-based fiber dispersion and not substantially fibrillated was 40:60. A sheet I was obtained in the same manner as in Example 1 except that.
For sheet I, thickness, density, tensile strength, tearing length, wet tensile strength, wet tearing length, root penetration 1, mater attachment workability 1 for maturing seedlings, and rice transplanting for mating seedlings The machine mounting workability 1 was measured, and the results are shown in Table 1.
[0040]
Comparative Example 3
In Example 1, a sheet J was obtained in the same manner as in Example 1 except that the sheet thickness was increased to be outside the scope of the present invention.
About sheet J, thickness, density, tensile strength, tearing length, wet tensile strength, wet tearing length, root penetrability 1, rice seedling machine workability 1 for maturing seedlings, and rice transplanting for mating seedlings The machine mounting workability 1 was measured, and the results are shown in Table 1. However, the amount of floor soil was set to 0.6 liters, which is about 40% less than that in the case of normal cultivation alone.
[0041]
Comparative Example 4
In Example 1, a sheet K was obtained in the same manner as in Example 1 except that the sheet thickness was reduced to be outside the scope of the present invention.
About sheet K, thickness, density, tensile strength, tearing length, wet tensile strength, wet tearing length, root penetrability 1, rice seedling machine mounting workability 1 for maturing seedlings, and rice transplanting for mating seedlings The machine mounting workability 1 was measured, and the results are shown in Table 1. However, the amount of floor soil was set to 0.8 liters, which is about 20% less than that of ordinary cultivated soil alone.
[0042]
Example 8
Dry wood pulverized material is used as wood fiber that has not been subjected to chemical treatment and is not substantially fibrillated, and the wood fiber and newspaper waste paper are mixed and disaggregated by a pulper, and the wood fiber by weight ratio: newspaper waste paper. = 70: 30 Cellulosic fiber dispersion raw material is obtained, then the sulfonic acid-modified polyvinyl alcohol hydrophilizing agent is 2.5% in solid content with respect to the cellulosic fiber weight, and the silicon hydrophilizing agent is made into the cellulosic fiber weight. On the other hand, after adding 0.5% by weight as a solid content and sufficiently agitating and mixing to make a hydrophilic treatment, it was supplied onto a long-mesh papermaking net to form a paper layer, and wound up to a predetermined thickness with a windup roll. Then, the sheet L was obtained by cutting, pressing and drying.
About sheet L, thickness, density, tensile strength, tearing length, wet tensile strength, wet tearing length, root penetration 2, workability for mating rice seedling machine 2 The mounting workability 2 and the rice planting suitability were measured, and the results are shown in Table 2. The amount of floor soil was set at 2.2 liters, which is about 30% less than the case of using only normal soil.
[0043]
Example 9
In Example 8, the weight ratio between the wood fiber not subjected to chemical treatment in the cellulosic fiber-dispersed raw material and not substantially fibrillated and the used newspaper was 80:20. Except for this, a sheet M was obtained in the same manner as in Example 8. About sheet M, thickness, density, tensile strength, tearing length, wet tensile strength, wet tearing length, root penetration 2, workability for mating rice seedling machine 2 The mounting workability 2 and the rice planting suitability were measured, and the results are shown in Table 2. The amount of floor soil was set to 1.9 liters, which is about 40% less than the case of normal cultivation alone.
[0044]
Example 10
In Example 8, the weight ratio of wood fibers not subjected to chemical treatment in the cellulose-based fiber-dispersed raw material and not substantially fibrillated and waste newspaper was 60:40. Except for this, a sheet N was obtained in the same manner as in Example 8. About sheet N, thickness, density, tensile strength, tearing length, wet tensile strength, wet tearing length, root penetration 2, workability for mating rice seedling machine 2 The mounting workability 2 and the rice planting suitability were measured, and the results are shown in Table 2. The amount of floor soil was set to 2.5 liters, which is about 20% less than that of ordinary soil alone.
[0045]
Example 11
In Example 8, the addition amount of the sulfonic acid-modified polyvinyl alcohol hydrophilizing agent is 1.0% by weight with respect to the weight of the cellulose fiber, and the addition amount of the silicon hydrophilizing agent is 0.2% by weight with respect to the weight of the cellulose fiber. In addition, after the hydrophilization treatment, the cyclic nitrogen compound mold agent is 60 ppm in solid content with respect to the weight of the cellulose fiber, and the powdery slow-release fertilizer is slightly soluble in water and 2 in solid content with respect to the weight of the cellulose fiber. A sheet O was obtained in the same manner as in Example 8, except that 0.0% by weight was added and the mixture was sufficiently stirred and mixed.
For sheet O, thickness, density, tensile strength, tearing length, wet tensile strength, wet tearing length, root penetrability 2, workability for mating rice seedling machine 2 The mounting workability 2 and the rice planting suitability were measured, and the results are shown in Table 2.
[0046]
Example 12
The sheet O obtained in Example 11 was laid on a seedling box, and a commercially available inorganic synthetic medium mat for subsoil replacement (same as that used in Comparative Example 8 described later) was placed on the seedling box, and after sufficient irrigation , Seeded directly on the synthetic medium mat, and measured root penetration 2, rice transplanter attachment workability 2 of mats at the time of seedling, rice transplanter attachment workability 2 and mating suitability of mats at the time of seedling, respectively, It is shown in Table 2. In this case, however, the thickness of the inorganic synthetic medium mat was adjusted to 15 mm.
[0047]
Comparative Example 5
Measures root penetration 2 when using only normal cultivated soil and no reinforcement sheet, rice planter installation workability 2 for seedling mats, rice transplanter installation workability 2 for seedling mats, and rice planting suitability The results are shown in Table 2. The floor soil volume was 3 liters.
[0048]
Comparative Example 6
For newspapers, thickness, density, tensile strength, tear length, wet tensile strength, wet tear length, root penetration 2, workability for mating rice seedling machines, mater transplanting for young seedling mats Workability 2 and rice planting suitability were measured, and the results are shown in Table 2. The floor soil volume was 3 liters.
[0049]
Comparative Example 7
Pulp seedling sheet carrying super absorbent polymer for underlay of commercially available floor soil Thickness, density, tensile strength, tear length, wet tensile strength, wet tear length, root penetration 2, root of mat The rice planter installation workability 2, the rice transplanter installation workability 2 and the rice planting suitability of the seedling mat were measured, and the results are shown in Table 2. The amount of floor soil was set to 2.5 liters, which is about 20% less than that of ordinary soil alone.
[0050]
Comparative Example 8
Commercially available inorganic fiber-based synthetic medium mats for subsoils with thickness, density, tensile strength, tear length, wet tensile strength, wet tear length, root penetration 2 The workability 2, the seedling attachment mat workability 2 and the rice planting suitability were measured, and the results are shown in Table 2. In this case, however, the inorganic fiber-based synthetic medium mat was sufficiently irrigated without floor soil and then directly sown on the synthetic medium mat.
[0051]
【The invention's effect】
The seedling sheet of the present invention, as can be seen from Examples 1 to 12, Comparative Examples 1 to 8, Tables 1 and 2 above, has not undergone chemical treatment and is not substantially fibrillated. As a result of high fiber content, thickness and density in the specified range, and further hydrophilization treatment, and the specified range of wet tensile strength and wet tear length under the specified wet conditions, excellent plant growth aptitude and sufficient It was possible to obtain a seedling raising sheet that has high strength and can improve the workability and efficiency of seedling raising work.
[0052]
The particularly excellent point of the seedling sheet of the present invention is that it combines the functions of the root penetration and the mat reinforcement at the time of attaching the rice transplanter, which have been difficult to achieve together. That is, according to the seedling raising method of the present invention, when mounted on a rice transplanter, even if there is little rooting and the mat formation is poor, the mat reinforcement effect of the seedling sheet of the present invention can be used without any trouble, Since the seedling-raising sheet of the invention functions as a part of floor soil, the amount of floor soil can be reduced by about 20 to 40% compared to the case of using only ordinary soil.
[0053]
In addition, it is possible to attach to the rice transplanter at the seedling stage, which is difficult with normal soil cultivation and also difficult to use with inorganic fiber-based synthetic medium, etc. Shortening (rough seedling raising takes about 3 weeks, while raising seedlings takes about 1/3, 5-7 days) ・ Increased sowing amount (160-180g of seedling raising seedlings per seedling box) On the other hand, it is possible to increase 20 to 50% with 200-250g for seedling raising seedlings.) ・ There are not many advantages such as reducing the number of nursery boxes used per unit area of Honda and improving the efficiency of seedling center rotation. You can enjoy it.
[Brief description of the drawings]
FIG. 1 is a depiction diagram showing a state where a mat obtained by the seedling raising method of the present invention is lifted with one hand using the seedling growing sheet of the present invention.
FIG. 2 is a drawing showing a state in which a mat obtained by the seedling raising method of the present invention is wound using the seedling sheet of the present invention in order to increase the efficiency of transplanting work to Honda.
[Explanation of symbols]
1. Nursery sheet
2. Floor soil or synthetic medium mat
3. Seedling
[Table 1]

[Table 2]

Claims

A hydrophilic treatment sheet containing 50 to 90% by weight of cellulosic fibers not subjected to chemical treatment and substantially not fibrillated, the sheet having a thickness of 0.8 to 5 mm and a density of Wet tension of 0.1 to 0.5 g / cm ³ and measured for the fiber orientation direction of the sheet after being immersed in distilled water at 20 ° C. for 5 minutes and the direction perpendicular to the fiber orientation direction. Each of strength (measurement based on JIS P-8113) and wet tear length (measurement based on JIS P-8113) has a wet tensile strength of 0.2 to 1.0 kg / 15 mm width, and the wet tear length is A seedling-raising sheet characterized by being 0.02-0.1 km.

The seedling-raising sheet according to claim 1, wherein the cellulosic fibers are wood fibers.

The seedling-raising sheet according to claim 1 or 2, wherein the hydrophilic treatment sheet is a papermaking sheet.

A hydrophilic treatment sheet containing 50 to 90% by weight of cellulosic fibers not subjected to chemical treatment and substantially not fibrillated, the sheet having a thickness of 0.8 to 5 mm and a density of Wet tension of 0.1 to 0.5 g / cm ³ and measured for the fiber orientation direction of the sheet after being immersed in distilled water at 20 ° C. for 5 minutes and the direction perpendicular to the fiber orientation direction. Each of strength (measurement based on JIS P-8113) and wet tear length (measurement based on JIS P-8113) has a wet tensile strength of 0.2 to 1.0 kg / 15 mm width, and the wet tear length is Place a sheet of 0.02-0.1 km in a seedling box and put culture soil as a floor soil on the sheet, or place a synthetic culture medium, irrigate, sowing, covering, budding, greening, milk At the seedling or seedling stage The seedling raising method using the seedling raising sheet characterized by transplanting to Honda.

The seedling raising method using the seedling-raising sheet according to claim 4, wherein the cellulosic fibers are wood fibers.

The seedling method using the seedling raising sheet according to claim 4 or 5, wherein the sheet is a papermaking sheet.