JP3609222B2

JP3609222B2 - Time-eluting coated granular fertilizer, blended fertilizer containing this as an active ingredient, and cultivation method using the blended fertilizer

Info

Publication number: JP3609222B2
Application number: JP30245096A
Authority: JP
Inventors: 正純内野; 通之芦原
Original assignee: Chisso Corp
Current assignee: JNC Corp
Priority date: 1996-10-04
Filing date: 1996-10-28
Publication date: 2005-01-12
Anticipated expiration: 2016-10-28
Also published as: JPH10158084A

Description

【０００１】
【発明の属する技術分野】
本発明は、優れた初期溶出抑制機能を有する時限溶出型被覆粒状肥料、該肥料を有効成分とする配合肥料およびこの配合肥料を用いた栽培方法に関する。
【０００２】
【背景技術】
農作物の栽培には、肥料が不可欠である。肥料の施用に際しては、作業の省力化の観点から、栽培の全期間を補えるだけの多量の肥料を一度に施用することが望ましいが、高濃度の肥料は、返って作物に対して害を及ぼすので、農作物の栽培期間中に数回に分けて、追肥というかたちで施用している。
【０００３】
特に、播種後暫くの間、作物は子房に蓄えた養分で発芽・発根できるので、肥料などの様な外部からの栄養分を必要としない。それどころか、過剰の栄養分となる肥料が、種子の周辺に存在すると、肥焼けや徒長等の生理障害を招き、それ以後の生育に多大な負の影響を及ぼし、酷い場合には枯死に至らしめることがある。従って、播種後暫くしてから、第１回目の施肥である基肥を施用するのが通例であった。
しかし、播種をした後、しばらくしてから基肥を施用し、さらに数回にわたる追肥を施用するという前記通例の栽培方法を用いて農作業を行うと、作業効率が極めて悪く、また、速効性肥料として親水性の化成肥料を用いると、流亡し易いので、肥料の利用効率が著しく低下する。
この様な欠点を克服するために、施用後に徐々に肥料が溶出してゆく徐放性被覆肥料や施用後一定期間溶出が抑制される期間（以下、誘導期間という。）と一定期間経過後に速やかに肥料が溶出する期間（以下、溶出期間という。）とを有する時限溶出型被覆肥料の開発が盛んに行われており（特開平６−８７６８４号公報、特公平５−２９６３４号公報、特開平４−２０２０７８号公報、特開平４−２０２０７９号公報、特開平８−１５１２８６号公報等）、これらの被覆肥料を播種と同時に施用する使用方法が検討されている（特開平７−１４７８１９号公報、特開平７−２５５２６８号公報等）。
【０００４】
しかしながら、施用直後から徐々に溶出を開始する除放性被覆肥料は、肥料成分の初期溶出を抑えることができないので、播種と同時に該被覆肥料を施用するのは難しく、施用できたとしても少量しかできないという欠点を有している。
一方、時限溶出型肥料は、誘導期間を有しているところから、除放性被覆肥料よりは多くの量を播種と同時に施用できる。しかし、現状の時限溶出型被覆肥料においては、誘導期間内での肥料成分の溶出を完全に抑制できるものがないので、播種と同時に多量に施用すると、濃度障害が起こる。したがって、栽培の全期間内もしくは栽培期間内に必要な肥料成分の大部分が含有される時限溶出型被覆肥料を、播種と同時に一度に施用することは事実上不可能であり、追肥作業を省略できるまでには至っていない。
【０００５】
この様に、時限溶出型被覆肥料の初期溶出抑制機能をいかに向上させるかが、作業効率と利用効率を向上させるための課題である。
前記公報等からの知見より、時限溶出型被覆肥料の研究は、該被覆肥料の外皮を形成している被膜の組成及びその層構造についてが大半であることが分かる。しかしながら、本発明者らも、上記内容の研究を重ねたところ、被膜の組成や被膜の層構造を研究してゆくだけでは、初期溶出抑制機能を改善するのに限界のあることが判明した。この理由は、時限溶出型被覆肥料の核となる肥料を有効成分とした芯材粒子の形状にあり、いびつな芯材粒子が存在すると、芯材粒子の表面に均一な厚みの被膜を形成させることができず、酷い時には被覆されていない場所ができ、時限溶出型被覆肥料にこの様な部分が存在すると初期溶出が速まったり、初期溶出抑制機能のないものとなるからである。
【０００６】
【発明が解決しようとする課題】
本発明の目的は、施用後一定期間肥料成分の溶出が全く起こらないか、溶出が起こったとしても極めて微量である優れた初期溶出抑制機能を有する時限溶出型被覆粒状肥料、該肥料を有効成分とする配合肥料およびこの配合肥料を用いた栽培方法を提供することである。
【０００７】
【課題を解決する為の手段】
本発明者らは、前記従来技術の現状に鑑み、鋭意検討を重ねた結果、肥料を有効成分として含み、かつ下記式に示される計算式より求められる円形度係数が０．７以上の芯材粒子を使用することにより、驚くべき初期溶出抑制機能、すなわち誘導期間の１／２が経過するまでの間の肥料成分の溶出率が１ｗｔ％以下である時限溶出型被覆粒状肥料を得ることができ、該肥料において、該肥料単独もしくは溶出速度の異なるものを組み合わせることにより、栽培の対象となる作物の成長に必要な養分を、必要な時期に与えることのできる配合肥料を得ることができ、該配合肥料を使用することにより、作物に悪影響を与えることなく作業効率と肥料成分の利用効率を極めて向上させることのできる栽培方法を見い出し、本発明を完成させた。
円形度係数＝（４π×粒子の投影面積）／（粒子投影図の輪郭の長さ）^２
【０００８】
すなわち、本発明は下記の（１）〜（３）の構成を有する。
（１）肥料を有効成分として含み、かつ下記式に示される計算式より求められる円形度係数が０．７以上である芯材粒子の表面上に、合成樹脂を主成分とする膜が覆われている時限溶出型被覆粒状肥料。
円形度係数＝（４π×粒子の投影面積）／（粒子投影図の輪郭の長さ）^２
（２）前記第（１）項に記載の時限溶出型被覆粒状肥料の１種以上が有効成分として含まれている配合肥料。
（３）前記第（２）項に記載の配合肥料を使用する栽培方法。
【０００９】
以下、本発明を詳細に説明する。
本発明の時限溶出型被覆粒状肥料とは、施肥後一定期間溶出が抑制される誘導期間と一定期間経過後速やかな溶出を開始する溶出期間とを有する粒状肥料であり、本発明では、施用後から芯材粒子中の肥料成分が１０ｗｔ％溶出するまでの期間を誘導期間（Ｄ１）、１０ｗｔ％溶出日から８０ｗｔ％溶出日までの期間を溶出期間（Ｄ２）とした。
本発明の時限溶出型被覆粒状肥料は、誘導期間／溶出期間の比率が０．２以上であり、施用後誘導期間の１／２が経過するまでの間の溶出量（１／２・Ｄ１）が１．０ｗｔ％以下という極めて優れた初期溶出抑制機能を有するものである。
【００１０】
この様な効果を付与させるためには、基本的には、芯材粒子が下記式に示される計算式より求められる円形度係数で０．７以上のものを使用しなければならない。
円形度係数＝（４π×粒子の投影面積）／（粒子投影図の輪郭の長さ）^２
円形度係数とは、粒子の円形度合いを知るための尺度であり、粒子が完全な真円の場合１．０となり、粒子形状が真円から崩れるに従って円形度係数が小さくなる。０．７未満の芯材粒子が増えると芯材粒子上に均一被膜を得ることができなくなるので、本発明において用いる芯材粒子は、全てが０．７以上のものであることが好ましいが、本発明の効果を大きく損なわない限りにおいて、０．７未満のものが若干量存在していても差し支えない。
なお上記した円形度係数は、株式会社ピアス製のＰＩＡＳ−ＩＶ等の市販の測定機器を用いることにより得ることができる。
【００１１】
芯材粒子は、肥料を必須成分とする原料を造粒することにより得ることができる。この様な造粒法としては、転動造粒法、押出し法、圧縮造粒法、破砕造粒法および噴流造粒法等のを用いることができる。本発明においては、これらの造粒法のいずれを使用しても良いが、芯材粒子のほぼ全てが、円形度係数０．７以上になるように製造しなければならない。
特に、押出し法、圧縮造粒法、破砕造粒法により得られる芯材粒子は、歪な形状になり易いので、該方法を用いる場合は、さらに整粒機等を用いて角取り処理を入念に行い、円形度係数０．７以上になるように成形する必要がある。
【００１２】
本発明において使用する芯材粒子には、肥料を有効成分とするものであれば何れのものであっても使用することが出来る。具体的には、単体若しくは複数の肥料成分からなる粒状物、単体若しくは複数の肥料成分を有効成分とし、該肥料成分と殺虫剤、殺菌剤、除草剤等の農薬活性成分とからなる粒状物、単体若しくは複数の肥料成分を有効成分とし、該肥料成分とベントナイト、ゼオライト、タルク、クレー、ケイソウ土等の不活性担体とからなる粒状物、一種以上の肥料成分と一種以上の農薬活性成分と一種以上の不活性担体とからなる粒状物等を挙げることが出来る。更には、前記粒状物の表面を合成樹脂や無機物で被覆した被覆粒状肥料を用いても構わない。
【００１３】
肥料の具体例としては、硫安、塩安、硝安、尿素、塩化加里、硫酸加里、硝酸加里、硝酸ソーダ、燐酸アンモニア、燐酸加里、燐酸石灰等の水溶性肥料、およびキレート鉄、酸化鉄、塩化鉄、ホウ酸、ホウ砂、硫酸マンガン、塩化マンガン、硫酸亜鉛、硫酸銅、モリブデン酸ナトリウム、モリブデン酸アンモニウム等の水溶性微量要素、ＯＭＵＰ（クロチリデンジウレア）、ＩＢＤＵ（イソブチリデンジウレア）やオキザマイド等の難水溶性肥料を挙げることができる。
【００１４】
本発明の時限溶出型被覆粒状肥料は、芯材粒子の表面上に合成樹脂を主成分とする被膜が被覆されている。該被膜においては、時限溶出機能を示すものであれば特に限定するものではなく、被膜を構成する組成、被膜の構造に特に限定はない。
被膜を得るための被覆方法としては、特に限定はないが、流動状態の芯材粒子に対し、合成樹脂を主成分とする材料（以下、被膜材料という。）が溶媒により溶解された混合溶解液を噴霧する一方、高速熱風流により、該芯材粒子上の溶媒を除去乾燥し、芯材粒子の表面に合成樹脂を主成分とする被膜を形成する製造方法が好ましい。
【００１５】
該製造方法に使用し得る被覆装置の一例として、図１に示される噴流層を用いて説明する。
この噴流層は、転動または流動状態にある芯材粒子５に対し、被膜材料の混合溶解液１２をポンプ６によって、スプレーノズル４により噴霧し、芯材粒子５の表面に吹き付けて、該表面を被覆すると同時並行的に、熱交換器８で加熱された高温気体をブロアー１０によって噴流塔１に下部から流入させ、該高速熱風流によって、該粒体表面に付着している混合溶解液中の溶媒を瞬時に蒸発乾燥させるものである。
【００１６】
被膜の主成分である合成樹脂としては、オレフィン重合体、オレフィンを含む共重合体、塩化ビニリデンを含む共重合体、ジエン系重合体、ワックス類、石油樹脂、天然樹脂、油脂およびその変性物から選ばれた１種または２種以上の物質ならびにアルキド樹脂等の熱硬化性樹脂を使用することが好ましく、中でもオレフィン重合体およびその共重合体がより好ましい。
【００１７】
具体例として、オレフィン重合体には、ポリエチレン、ポリプロピレン、エチレン・プロピレン共重合体、エチレン・一酸化炭素共重合体、ポリブテン、ブテン・エチレン共重合体、ブテン・プロピレン共重合体、ポリスチレン等を例示でき、オレフィンを含む共重合体には、エチレン・酢酸ビニル共重合体、エチレン・酢酸ビニル・一酸化炭素共重合体、エチレン・アクリル酸共重合体、エチレン・メタアクリル酸エステル共重合体等を例示でき、塩化ビニリデンを含む共重合体には、塩化ビニリデン・塩化ビニル共重合体を例示でき、ジエン系重合体には、ブタジエン重合体、イソプレン重合体、クロロプレン重合体、ブタジエン・スチレン共重合体、ＥＰＤＭ重合体、スチレン・イソプレン共重合体等を例示でき、ワックス類には、密ロウ、木ロウ、パラフィン等を例示でき、天然樹脂には、天然ゴム、ロジン等を例示でき、油脂及びその変性物には、硬化物、固形脂肪酸および金属塩等を例示することができる。
また、合成樹脂とともに界面活性剤を使用しても良い。界面活性剤は、施用後の肥料成分の溶出をコントロールする機能を有してしている。
【００１８】
本発明の配合肥料は、肥料を有効成分として含み、かつ下記式に示される計算式より求められる円形度係数が０．７以上である芯材粒子の表面上に、合成樹脂を主成分とする膜が覆われている時限溶出型被覆粒状肥料の１種以上が有効成分として含まれる配合肥料である。
円形度係数＝（４π×粒子の投影面積）／（粒子投影図の輪郭の長さ）^２
本発明の配合肥料は、１種以上の時限溶出型被覆粒状肥料が配合されていれば、他の配合物およびその配合割合に特に制限はないが、作物の必要養分量の経時変化（以下、作物の養分吸収パターンと言う。）に合わせて肥料成分が溶出するように時限溶出型被覆粒状肥料が配合されていることが好ましい。
【００１９】
作物の養分吸収パターンは、各県農業試験場、各農業改良普及所、各農協の営農指導課における蓄積データを参照することにより推定できる。一般に、作物の養分吸収パターンは、作物の時期別養分吸収量と、地力と呼ばれる時期別土壌養分供給量との差から求めることができる。また、本発明の時限溶出型被覆粒状肥料の経時的溶出は、使用する地域によって若干の違いが生じるが、使用する地域の過去の月日別地温によって推定することができる。
本発明の配合肥料は、前記蓄積データを十分に考慮した上、養分吸収パターンと本発明の時限溶出型被覆粒状肥料の経時的溶出とが近似するように調整することにより得ることができる。
この際の地温とは、作土の表層から深さ５ｃｍの部位の温度であるが、この地温はほぼ気温と見なすことが出き、その地域の栽培期間中の平均気温で代用することができる。
【００２０】
また、作物は、各々特有の養分吸収パターンを有しており、成長に伴って必要となる栄養素（窒素、燐酸、加里等）も異なるため、前記時限溶出型被覆粒状肥料の単独使用では、複数種の作物に対応させるには限界がある。時限溶出型被覆粒状肥料を多量に施用して、絶えず養分吸収パターンより過剰の肥料成分が溶出する様にしておけば単独使用も可能であるが、利用効率が著しく悪化する。
従って、本発明の配合肥料は、肥料成分の溶出開始時期および溶出速度の異なる２種以上の時限溶出型被覆粒状肥料を組み合わせ、栽培の対象となる作物の養分吸収パターンに合わせて溶出するように配合調整したり、肥料成分として用いている栄養素が異なる２種以上の時限溶出型被覆粒状肥料を組み合わせ、栽培の対象となる作物の必要栄養素が成長に合わせて溶出するように配合調整しておくのが好ましい。
また、本発明の効果を著しく阻害しない範囲において、本発明とは異なる被覆肥料や化成肥料を配合しても良い。
【００２１】
本発明の栽培方法は、肥料を有効成分として含み、かつ下記式に示される計算式より求められる円形度係数が０．７以上である芯材粒子の表面上に、合成樹脂を主成分とする膜が覆われている時限溶出型被覆粒状肥料の１種以上が有効成分として含まれる配合肥料を使用する方法である。
円形度係数＝（４π×粒子の投影面積）／（粒子投影図の輪郭の長さ）^２
【００２２】
本発明の配合肥料の使用方法に特に限定はないが、育苗箱を用いた全量基肥施肥法が最適である。
全量基肥施肥法とは、栽培期間内に必要な肥料成分の全量若しくはその大部分を、育苗開始時に育苗箱へ施用するものである。通常、作物の育苗における肥料成分の溶出許容量は、育苗培土１００ｍｌ当たり窒素成分で１０〜２０ｍｇであると云われており、この範囲を超えて肥料成分の溶出が行われると、枯死や徒長などの肥料成分による濃度障害が発生する。しかし、育苗箱を用いた全量基肥施肥法に代表されるような、作物の根と肥料とが直接的に接触した状態にある施肥法（接触施肥法）においては、その溶出許容量は更に小さくなり、播種直後から育苗中期（全育苗期間の１／２）までの間では、僅かに溶出した肥料成分でも障害が発生する。
しかし、本発明の配合肥料を全量基肥施肥法に使用すると、播種直後から育苗中期までの間の肥料成分溶出量を極度に抑制することができるので、作物が濃度障害を起こすことがない上、種籾から発根した根は成長と共に該肥料と接触し、ついには根で該肥料を抱えるような状態になり、生長した苗を本田に移植する際にはそのままの状態で移植されるため、根が接触している該肥料から肥料成分を直接吸収することができ、肥料の利用効率を大幅に向上させることができるのである。
【００２３】
【発明の効果】
本発明の時限溶出型被覆粒状肥料は、誘導期間／溶出期間の比率が０．２以上であり、施用後誘導期間の１／２が経過するまでの間の溶出量が１．０ｗｔ％以下という極めて優れた初期溶出抑制機能を有するものであり、本発明の配合肥料は、対象作物の養分吸収パターンに合わせた肥料溶出が起こるものであり、本発明の栽培方法は、作物に悪影響を与えず、作業効率と肥料の利用効率を著しく向上させることのできる方法である。
【００２４】
【実施例】
以下に実施例によって本発明を説明するが、本発明はこれら実施例により限定されるべきものではない。尚、以下の実施例における「％」は特に断りがない限り「重量％」である。
【００２５】
芯材原料粒子の製造
芯材粒子を得るための原料となる芯材原料粒子を、図２に示すフローシートに基づいて得た。
（芯材原料粒子Ａの製造）
原料となる尿素（８ｍｅｓｈパス品）５０Ｋｇを、ホッパーＡから、スクリューフィーダーＢとロールプレスＣから成るピストン油圧２７０ｋｇ／ｃｍ^２Ｔに設定したロールコンパクター（アレクサンダー乾式造粒機、ＷＰ−４００×３３０Ｖ型）に供給することによりフレーク状物とした。次に、該フレーク状物を解砕機Ｄで砕いた後、振動篩Ｅで分級し、６〜８ｍｅｓｈのサイズを有する１次製品を得た。この時、６ｍｅｓｈより大きいサイズであるオーバーサイズ品は、再び解砕機Ｄに導き、６ｍｅｓｈより小さくなるまで粉砕を繰り返す。一方、８ｍｅｓｈより小さいサイズであるアンダーサイズ品は、ホッパーＡに返送され、再度フレーク状物に成形される。１次製品は、フレコンＦに収納され、芯材原料粒子Ａとして使用される。
（芯材原料粒子Ｂの製造）
原料を尿素から硫安（８ｍｅｓｈパス品）に代えた以外は、（芯材原料粒子Ａの製造）に準じて芯材原料粒子Ｂを得た。
（芯材原料粒子Ｃの製造）
原料を尿素から塩化加里（８ｍｅｓｈパス品）に代えた以外は、（芯材原料粒子Ａの製造）に準じて芯材原料粒子Ｃを得た。
【００２６】
芯材粒子の製造
（芯材粒子Ａの製造）
芯材原料粒子Ａを図２のフローシートに示される振動篩Ｇで分級して７〜８ｍｅｓｈの芯材粒子Ａを得、芯材粒子Ａの円形度係数を株式会社ピアス製のＰＩＡＳ−ＩＶを用いて測定した。測定条件は、ランダムに取り出した粒子５０個を用い、しきい値１２０−１２０で行った。円形度係数の測定結果を表１に示す。
（芯材粒子Ｂの製造）
芯材原料粒子Ａを、回転円盤式整粒機Ｈ（不二パウダル製、マルメライザーＱＪ２３０）で、円形度係数が０．７以上になるまで平滑化処理を行った。その処理方法は、図３のフローシートの通りであり、芯材原料粒子Ａを計量して回転円盤式整粒機Ｈに供給し、下記の運転条件で角取りした後、振動篩Ｊで分級し７〜８ｍｅｓｈの芯材粒子Ｂを得た。円形度係数を、（芯材粒子Ａの製造）に準じて測定した。円形度係数の測定結果を表１に示す。
運転条件
運転方式：回分式
運転時間：１ｍｉｎ
目皿ピッチ：４ｍｍ
速度比：０．３
仕込量：２ｋｇ（１回当たり）
（芯材粒子Ｃの製造）
運転時間１ｍｉｎを５ｍｉｎにした以外は、（芯材粒子Ｂの製造）に準じて、芯材粒子Ｃを得た。得られた芯材粒子Ｃの円形度係数を、（芯材粒子Ａの製造）に準じて測定した。円形度係数の測定結果を表１に示す。
（芯材粒子Ｄの製造）
運転時間１ｍｉｎを９ｍｉｎにした以外は、（芯材粒子Ｂの製造）に準じて、芯材粒子Ｄを得た。得られた芯材粒子Ｄの円形度係数を、（芯材粒子Ａの製造）に準じて測定した。円形度係数の測定結果を表１に示す。
（芯材粒子Ｅの製造）
芯材原料粒子Ａを芯材原料粒子Ｂに代え、運転時間１ｍｉｎを５ｍｉｎにした以外は、（芯材粒子Ｂの製造）に準じて、芯材粒子Ｅを得た。得られた芯材粒子Ｅの円形度係数を、（芯材粒子Ａの製造）に準じて測定した。円形度係数の測定結果を表１に示す。
（芯材粒子Ｆの製造）
芯材原料粒子Ａを芯材原料粒子Ｃに代え、運転時間１ｍｉｎを５ｍｉｎにした以外は、（芯材粒子Ｂの製造）に準じて、芯材粒子Ｆを得た。得られた芯材粒子Ｆの円形度係数を、（芯材粒子Ａの製造）に準じて測定した。円形度係数の測定結果を表１に示す。
【００２７】
時限溶出型被覆粒状肥料の製造
（時限溶出型被覆粒状肥料１〜１６の製造）
時限溶出型被覆粒状肥料の製造を図１のフローシートにより説明すると、塔径２５０ｍｍ、高さ２０００ｍｍ、空気噴出口径５０ｍｍ、円錘角５０度の形状を有する噴流塔１内へ、高温熱風を下部から上部に向けて流入する。高温熱風は、ブロアー１０から送風され、オリフィス流量計９を通り、熱交換器８によって高温に加熱されて、噴流塔１に流入され、噴流塔１の上部に設置されている排ガス用出口３から排出される。この高温熱風が循環している噴流塔１の内部に、表２に示される芯材粒子Ａ〜Ｆ（フローシート上では、芯材粒子５としている。）を、噴流塔１の側面に設置されている芯材粒子投入口２から１０Ｋｇ投入し、図１に示されるように芯材粒子５を流動させる。この際、流量および熱風温度は、各サンプル毎に適宜調節する必要があり、流量はオリフィス流量計で測定しながら調節し、熱風温度は、Ｔ１の熱風温度、Ｔ２の粒剤温度、Ｔ３の排気温度を測定しながら調節する。本実施各例においては、流量（オリフィス流量計９）４ｍ^３／ｍｉｎ、熱風温度（熱風温度Ｔ１）１００℃±２℃で実施した。
他方、溶解槽１１に、表２に示される被膜材料組成の各成分と溶媒としてトルエンを投入し、混合撹拌することによって、１．５重量％の均一な被膜材料の混合溶解液１２を得る。該溶解液１２は、ポンプ６によって噴流塔１の下部に設置されている開口０．８ｍｍフルコン型一流体ノズルであるスプレーノズル４に、流速０．１ｋｇ／ｍｉｎで輸送され、流動中の芯材粒子５に、噴霧され、吹き付けられる。この時、該溶解液１２の温度が８０℃以下にならないように、溶解槽１１と溶解槽１１からスプレーノズル４に至るまでの配管とを二重構造にしておき、蒸気を通して、該溶解液１２を加温しながら輸送した。
該吹き付け行程は、流動中の芯材粒子５の粉体温度Ｔ２が所定の温度に達した時点から開始し、所定時間スプレーした後、所定時間の乾燥を実施し、乾燥が終了した時点で、ブロアー１０を止め、被覆された芯材粒子５を、噴流塔１の最下部にある抜き出し口７より排出し、表２に記載する時限溶出型被覆粒状肥料１〜１６を得た（ただし、時限溶出型被覆粒状肥料１〜６および１５〜１６は、第１層の被膜材料組成物を吹き付け処理した後、第２層の被膜材料組成物を吹き付け処理した。）。
【００２８】
（溶出試験）
時限溶出型被覆粒状肥料の製造で得られた時限溶出型被覆粒状肥料１〜１６をそれぞれ１０ｇづつ２００ｍｌの水中に浸漬し、２５℃に静置する。所定期間後該肥料を水から抜く取り、水中に溶出した肥料成分を定量分析により求める。測定後、該肥料を新水２００ｍｌ入れて、２５℃に静置し、所定期間後同様な肥料成分の定量分析を行なう。この様な操作を繰り返し、水中に溶出した肥料成分の溶出累計と日数の関係をグラフ化して溶出速度曲線を作成した。その結果を図４に示す。また、浸漬開始から１０ｗｔ％溶出に至るまでの日数（誘導期間）を「Ｄ１」とし、それ以降８０ｗｔ％溶出に至るまでの日数（溶出期間）を「Ｄ２」とし、誘導期間の１／２にあたる時点での溶出率を「１／２・Ｄ１」とした。その結果を表３に示す。「１／２・Ｄ１」の結果より明らかなように、円形度係数が０．７以上の芯材粒子を使用して得た時限溶出型被覆粒状肥料（２、４、６、８、１０〜１４、１６）は、円形度係数が０．７未満の芯材粒子を使用して得た時限溶出型被覆粒状肥料（１、３、５、７、９、１５）と比較して、初期溶出量が極めて微量であることが判る。
【００２９】
（キュウリ栽培用配合肥料の調整）
熊本県水俣市袋（地名）でのキュウリ（品種：あそみどり）の露地栽培における播種から収穫までの期間の該キュウリの養分要求曲線（前記養分吸収パターン）を、同地において前年度測定した栽培期間中の土壌養分供給曲線（前記時期別土壌養分供給量）と該キュウリの養分吸収曲線（前記時期別養分吸収量）とから割り出した。これらの曲線を得るために使用した基本データは、前年度同地で実施した同作物の試作データである。この様にして得られた前年度の該キュウリの養分要求曲線を図５に示す。
次に、時限溶出型被覆粒状肥料１２および１６を組み合わせて、該養分要求曲線に近似する溶出曲線を有する配合肥料Ａ得た。配合肥料Ａは、図４記載の溶出曲線Ｎｏ．１２とＮｏ．１６とを基準とし、９５：５、９０：１０・・・５：９５と５単位毎に組成比を代え、それぞれの組成比から得られる仮想溶出曲線を描き、この中から該養分要求曲線に最も近似する溶出曲線を有する組成比を選んだ。その結果、配合肥料Ａは、時限溶出型被覆粒状肥料１２と１６を６０対４０の比率で組み合わせたものが最も適当であることが分かった。配合肥料Ａの溶出曲線を実施例配合肥料溶出曲線として、図５に示す。この際、該養分吸収曲線は、栽培期間中の気温変化（１８℃〜３２℃程度の範囲）を取り入れた曲線であるが、栽培期間中の平均気温がほぼ２５℃なので、２５℃の溶出曲線が記載されている図４を組成比特定の基準とした。また、同様に、時限溶出型被覆粒状肥料７および９を組み合わせて、該養分要求曲線に近似する溶出曲線を有する配合肥料Ｂ得た。配合肥料Ｂは、時限溶出型被覆粒状肥料７と９を４０対６０の比率で組み合わせたものが最も適当であることが分かった。配合肥料Ｂの溶出曲線を比較例配合肥料溶出曲線として、図５に示す。
図５より、本発明の配合肥料である配合肥料Ａにおいては、初期溶出が極めて低く抑えられており、その溶出曲線はキュウリの養分要求曲線に非常に近似しており、一方本発明の配合肥料とは異なる配合肥料Ｂにおいては、初期溶出の抑制は不充分であり、その溶出曲線はキュウリの養分要求曲線とほぼ近似しているが、初期段階の溶出曲線が明らかに異なっていることが分かる。
【００３０】
（配合肥料を用いたキュウリ栽培試験）
熊本県水俣市袋（地名）にある圃場において、配合肥料Ａと配合肥料Ｂを用いたキュウリの栽培試験を行った。栽培試験は、通常の農作業形式に準拠した慣行区試験、配合肥料Ａを用いた実施例区試験、配合肥料Ｂを用いた比較例区試験の３種類の栽培形式で行った。各試験の詳細を以下に示す。
慣行区試験
予め調整しておいた肥料が全く含有されていない育苗培土１００ｍｌに対し、育苗用肥料として窒素成分（Ｎ成分、以下Ｎと略す。）１０ｍｇ、リン成分（Ｐ_２Ｏ_５成分、以下Ｐと略す。）１０ｍｇ、カリ成分（Ｋ_２Ｏ成分、以下Ｋと略す。）１０ｍｇを混合した育苗培土資材を、直径１０ｃｍタイプのビニールポットに４００ｍｌ充填した後、キュウリ種子（品種：あそみどり）１粒を播種し、更にその上に該育苗培土を覆土して、４月２６日より５月６日までビニールポット内で苗を育てた。ビニールポットでの育苗が終了した後、該苗を圃場に１８００本／１０ａの密度で移植し、圃場での栽培を開始した。その後、７月６日から主茎の収穫を開始し、７月２６日から側枝の収穫を開始し、９月２０日に収穫して、栽培を終了した。
苗を圃場に移植し、苗が圃場に定植してから収穫までの間に、肥料成分としてＮが１４％、Ｐが１４％、Ｋが１４％含有する高度化成肥料を４回に分けて施肥した。施肥量は、４回の施肥でＮ−Ｐ−Ｋが圃場１０アール当たり、１５Ｋｇ−１５Ｋｇ−１５Ｋｇとなる様に調整した。
実施例区試験
予め調整しておいた肥料が全く含有されていない育苗培土１００ｍｌに対し、育苗用肥料として、Ｐを１０ｍｇ、Ｋを１０ｍｇ混合した育苗培土資材４００ｍｌと配合肥料Ａ内に存在するＮが８．３３ｇ（圃場１０アール当たりのＮが１５Ｋｇに相当）となる量の配合肥料Ａとをよくかき混ぜて、直径１０ｃｍタイプのビニールポットに充填した後、キュウリ種子（品種：あそみどり）１粒を播種し、更にその上に該育苗培土を覆土して、４月２６日より５月６日までビニールポット内で苗を育てた。ビニールポットでの育苗が終了した後、該苗を圃場に１８００本／１０ａの密度で移植し、圃場での栽培を開始した。その後、７月６日から主茎の収穫を開始し、７月２６日から側枝の収穫を開始し、９月２０日に収穫して、栽培を終了した。
苗を圃場に移植し、苗が圃場に定植してから収穫までの間に、肥料成分としてＰが１４％、Ｋが１４％含有する高度化成肥料を４回に分けて施肥した。施肥量は、４回の施肥でＰ−Ｋが圃場１０アール当たり、１５Ｋｇ−１５Ｋｇとなる様に調整した。
比較例区試験
予め調整しておいた肥料が全く含有されていない育苗培土１００ｍｌに対し、育苗用肥料として、Ｐを１０ｍｇ、Ｋを１０ｍｇ混合した育苗培土資材４００ｍｌと配合肥料Ｂ内に存在するＮが８．３３ｇ（圃場１０アール当たりのＮが１５Ｋｇに相当）となる量の配合肥料Ｂとをよくかき混ぜて、直径１０ｃｍタイプのビニールポットに充填した後、キュウリ種子（品種：あそみどり）１粒を播種し、更にその上に該育苗培土を覆土して、４月２６日より５月６日までビニールポット内で苗を育てた。ビニールポットでの育苗が終了した後、該苗を圃場に１８００本／１０ａの密度で移植し、圃場での栽培を開始した。その後、７月６日から主茎の収穫を開始し、７月２６日から側枝の収穫を開始し、９月２０日に収穫して、栽培を終了した。
苗を圃場に移植し、苗が圃場に定植してから収穫までの間に、肥料成分としてＰが１４％、Ｋが１４％含有する高度化成肥料を４回に分けて施肥した。施肥量は、４回の施肥でＰ−Ｋが圃場１０アール当たり、１５Ｋｇ−１５Ｋｇとなる様に調整した。
【００３１】
以上の様に、慣行区試験ではＮの追肥を行い、比較例区試験および実施例区試験では、Ｎの追肥を行わずにキュウリの栽培を行った。
この結果、比較例区試験において、発芽が全く起こらなかった（発芽率０％）。これは、明らかに生育初期における肥料成分の過剰溶出が原因である。図５の比較例配合肥料溶出曲線からも明らかなように、配合肥料Ｂでは、初期溶出が充分に抑えられておらず、この過剰溶出がキュウリの種子に対して濃度障害を起こしたのである。
一方、実施例区試験においては、発芽率が９７％であり、慣行区試験の発芽率９８％とほぼ同等の良好な生育状態であった。
また、実施例区試験における収穫指数も、慣行区の収穫量を１００とするのに対し１０２であり、Ｎの追肥を行った慣行区試験と全く遜色のない収穫量であった。この様に実施例区試験においては、慣行区試験（従来の農作業）の半分程度の減肥を行っても、同等以上の収量が得られることが分かった。本発明の配合肥料を播種と同時に施肥する栽培方法を用いれば、作業の省力化と肥料の利用効率とを大幅に向上することができる。
【００３２】
【表１】

【００３３】
【表２】

【００３４】
【表３】

【図面の簡単な説明】
【図１】噴流層のフローシート
【図２】圧縮造粒法のフローシート
【図３】平滑化処理法のフローシート
【図４】時限溶出型被覆粒状肥料（５〜９、１２、１５、１６）の溶出速度曲線
【図５】キュウリの養分要求曲線と配合肥料ＡおよびＢの各溶出曲線
【符号の説明】
１．噴流塔
２．芯材粒子投入口
３．排ガス用出口
４．スプレーノズル
５．芯材粒子
６．ポンプ
７．抜き出し口
８．熱交換器
９．オリフィス流量計
１０．ブロアー
１１．溶解槽
１２．被膜材料の混合溶解液
Ｔ１．熱風温度
Ｔ２．粒体温度
Ｔ３．排気温度
ＳＬ．スチーム
Ａ．ホッパー
Ｂ．スクリューフィーダー
Ｃ．ロールプレス
Ｄ．解砕機
Ｅ．振動篩
Ｆ．貯蔵部（フレコン）
Ｇ．振動篩
Ｈ．回転円盤式整粒機
Ｊ．振動篩[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a time-dissolved coated granular fertilizer having an excellent initial dissolution control function, a blended fertilizer containing the fertilizer as an active ingredient, and a cultivation method using the blended fertilizer.
[0002]
[Background]
Fertilizer is indispensable for the cultivation of crops. When applying fertilizer, it is desirable to apply a large amount of fertilizer at one time to compensate for the entire cultivation period from the viewpoint of labor saving. However, high-concentration fertilizer is harmful to crops in return. Therefore, it is divided into several times during the cultivation period of crops and applied in the form of additional fertilization.
[0003]
In particular, for a while after sowing, the crops can germinate and root with the nutrients stored in the ovary, so no external nutrients such as fertilizers are required. On the contrary, if fertilizer, which is an excessive nutrient, is present in the vicinity of the seeds, it may cause physiological disorders such as fertilization and chief, and will have a great negative effect on the subsequent growth, and if it is severe, it will lead to death. There is. Therefore, it was customary to apply the basic fertilizer, which is the first fertilization, for a while after sowing.
However, after sowing, after applying the basic fertilizer after a while, and using the usual cultivation method of applying additional fertilizer several times, the work efficiency is extremely poor, and as a fast-acting fertilizer If a hydrophilic chemical fertilizer is used, it tends to run away, so the fertilizer utilization efficiency is significantly reduced.
In order to overcome such drawbacks, a sustained-release coated fertilizer in which the fertilizer gradually elutes after application, a period during which elution is suppressed for a certain period after application (hereinafter referred to as an induction period), and promptly after a certain period has elapsed. Development of time-dissolved coated fertilizer having a period during which fertilizer is eluted (hereinafter referred to as an elution period) has been actively carried out (Japanese Patent Laid-Open Nos. 6-87684, 5-29634, and 4-202078, JP-A-4-202079, JP-A-8-151286, etc.), and methods of using these coated fertilizers simultaneously with sowing have been studied (JP-A-7-147819, JP-A-7-255268).
[0004]
However, sustained-release coated fertilizers that gradually start elution immediately after application cannot suppress the initial elution of fertilizer components, so it is difficult to apply the coated fertilizer simultaneously with sowing, and even if applied, only a small amount can be applied. It has the disadvantage that it cannot.
On the other hand, the time-eluting fertilizer has an induction period, so that it can be applied at the same time as sowing in a larger amount than the controlled-release fertilizer. However, none of the current time-dissolved coated fertilizers can completely suppress the elution of fertilizer components within the induction period, and thus concentration disturbance occurs when applied in large quantities simultaneously with sowing. Therefore, it is practically impossible to apply a time-dissolved coated fertilizer containing most of the necessary fertilizer components during the entire cultivation period or during the cultivation period at the same time as sowing, omitting additional fertilization work. It hasn't been done yet.
[0005]
Thus, how to improve the initial dissolution control function of the time-dissolved coated fertilizer is a problem for improving work efficiency and utilization efficiency.
From the findings from the above publications and the like, it can be seen that most studies on time-dissolved coated fertilizer are about the composition of the coating forming the outer coat of the coated fertilizer and its layer structure. However, as a result of repeated studies on the above contents, the present inventors have found that there is a limit to improving the initial elution suppression function only by studying the composition of the film and the layer structure of the film. The reason for this is the shape of the core material particles containing the fertilizer that is the core of the time-dissolved coated fertilizer as an active ingredient, and if distorted core material particles are present, a film having a uniform thickness is formed on the surface of the core material particles. This is because, when it is severe, there is a place where it is not covered, and when such a portion is present in the time-dissolved fertilizer, the initial elution is accelerated or the initial elution suppression function is not provided.
[0006]
[Problems to be solved by the invention]
The object of the present invention is to provide a timed elution-type coated granular fertilizer having an excellent initial elution control function which is extremely small even if elution occurs, or an effective ingredient of the fertilizer for a certain period after application. And a cultivation method using the blended fertilizer.
[0007]
[Means for solving the problems]
As a result of intensive studies in view of the current state of the prior art, the inventors of the present invention include a fertilizer as an active ingredient, and a core material having a circularity coefficient of 0.7 or more obtained from the calculation formula shown below. By using particles, it is possible to obtain a time-dissolved coated granular fertilizer that has a surprising initial elution suppression function, that is, the elution rate of the fertilizer component is 1 wt% or less until ½ of the induction period elapses. In addition, in the fertilizer, by combining the fertilizer alone or those having different elution rates, it is possible to obtain a blended fertilizer that can provide nutrients necessary for the growth of the crop to be cultivated at a necessary time, By using the blended fertilizer, the present inventors have found a cultivation method that can greatly improve the working efficiency and the utilization efficiency of the fertilizer components without adversely affecting the crop, and have completed the present invention.
Circularity coefficient = (4π × projection area of particle) / (length of contour of particle projection)²
[0008]
That is, the present invention has the following configurations (1) to (3).
(1) A film containing synthetic resin as a main component is covered on the surface of core material particles containing fertilizer as an active ingredient and having a circularity coefficient of 0.7 or more obtained from the following formula. Time-dissolved coated granular fertilizer.
Circularity coefficient = (4π × projection area of particle) / (length of contour of particle projection)²
(2) A blended fertilizer containing at least one type of time-dissolved coated granular fertilizer according to item (1) as an active ingredient.
(3) A cultivation method using the blended fertilizer according to item (2).
[0009]
Hereinafter, the present invention will be described in detail.
The time-dissolved coated granular fertilizer of the present invention is a granular fertilizer having an induction period in which elution is suppressed for a certain period after fertilization and an elution period in which rapid elution is started after the lapse of a certain period. The period from the elution period (D1) until the fertilizer component in the core particles is eluted by 10 wt% was defined as the elution period (D2).
In the time-dissolved coated granular fertilizer of the present invention, the ratio of induction period / elution period is 0.2 or more, and the elution amount until 1/2 of the induction period after application elapses (1/2 · D1) Has an extremely excellent initial elution suppression function of 1.0 wt% or less.
[0010]
In order to give such an effect, basically, the core particles must have a circularity coefficient of 0.7 or more obtained from the calculation formula shown below.
Circularity coefficient = (4π × projection area of particle) / (length of contour of particle projection)²
The circularity coefficient is a scale for knowing the degree of circularity of a particle. When the particle is a perfect circle, the circularity coefficient is 1.0, and the circularity coefficient decreases as the particle shape collapses from the perfect circle. If the number of core particles less than 0.7 increases, a uniform film cannot be obtained on the core particles. Therefore, the core particles used in the present invention are all preferably 0.7 or more, As long as the effect of the present invention is not significantly impaired, a slight amount less than 0.7 may be present.
The circularity coefficient described above can be obtained by using a commercially available measuring instrument such as PIAS-IV manufactured by Pierce Co., Ltd.
[0011]
The core material particles can be obtained by granulating a raw material containing a fertilizer as an essential component. As such a granulation method, a rolling granulation method, an extrusion method, a compression granulation method, a crushing granulation method, a jet granulation method, or the like can be used. In the present invention, any of these granulation methods may be used, but almost all of the core particles must be produced so that the circularity coefficient is 0.7 or more.
In particular, the core particles obtained by the extrusion method, the compression granulation method, and the crushing granulation method tend to be distorted. And it is necessary to mold so that the circularity coefficient is 0.7 or more.
[0012]
As the core particles used in the present invention, any particles can be used as long as they contain fertilizer as an active ingredient. Specifically, a granular material composed of a single or a plurality of fertilizer components, a single or a plurality of fertilizer components as an active ingredient, a granular material composed of the fertilizer components and agrochemical active ingredients such as insecticides, fungicides, herbicides, A single substance or a plurality of fertilizer ingredients as active ingredients, granular materials comprising the fertilizer ingredients and an inert carrier such as bentonite, zeolite, talc, clay, diatomaceous earth, one or more fertilizer ingredients and one or more agrochemical active ingredients and one kind The granular material which consists of the above inert support | carriers etc. can be mentioned. Furthermore, you may use the covering granular fertilizer which coat | covered the surface of the said granular material with the synthetic resin or the inorganic substance.
[0013]
Specific examples of fertilizers include ammonium sulfate, ammonium sulfate, ammonium nitrate, urea, potassium chloride, potassium sulfate, potassium nitrate, sodium nitrate, ammonium phosphate, ammonium phosphate, potassium phosphate, lime phosphate and other water-soluble fertilizers, and chelated iron, iron oxide, chloride Water-soluble trace elements such as iron, boric acid, borax, manganese sulfate, manganese chloride, zinc sulfate, copper sulfate, sodium molybdate, ammonium molybdate, OMUP (clotylidene diurea), IBDU (isobutylidene diurea) and oxamide Examples include poorly water-soluble fertilizers.
[0014]
In the time-dissolved coated granular fertilizer of the present invention, a coating containing a synthetic resin as a main component is coated on the surface of the core particles. The film is not particularly limited as long as it exhibits a timed elution function, and the composition of the film and the structure of the film are not particularly limited.
The coating method for obtaining the coating is not particularly limited, but a mixed solution in which a material mainly composed of a synthetic resin (hereinafter referred to as a coating material) is dissolved in a fluidized core material particle by a solvent. On the other hand, a production method in which the solvent on the core material particles is removed and dried by a high-speed hot air flow to form a film mainly composed of a synthetic resin on the surface of the core material particles is preferable.
[0015]
An example of a coating apparatus that can be used in the manufacturing method will be described using a spouted bed shown in FIG.
The spouted bed sprays the coating material mixed solution 12 onto the core material particles 5 in a rolling or fluidized state by the pump 6 by the spray nozzle 4 and sprays it onto the surface of the core material particles 5. In parallel with the coating, the hot gas heated by the heat exchanger 8 is caused to flow into the jet tower 1 from the lower part by the blower 10, and in the mixed solution adhering to the particle surface by the high-speed hot air flow. This solvent is instantly evaporated to dryness.
[0016]
Synthetic resins that are the main components of the coating include olefin polymers, copolymers containing olefins, copolymers containing vinylidene chloride, diene polymers, waxes, petroleum resins, natural resins, oils and fats, and modified products thereof. It is preferable to use one or two or more selected substances and thermosetting resins such as alkyd resins, among which olefin polymers and copolymers thereof are more preferable.
[0017]
Specific examples of the olefin polymer include polyethylene, polypropylene, ethylene / propylene copolymer, ethylene / carbon monoxide copolymer, polybutene, butene / ethylene copolymer, butene / propylene copolymer, and polystyrene. The olefin-containing copolymer includes ethylene / vinyl acetate copolymer, ethylene / vinyl acetate / carbon monoxide copolymer, ethylene / acrylic acid copolymer, ethylene / methacrylic acid ester copolymer, etc. Examples of the copolymer containing vinylidene chloride include vinylidene chloride / vinyl chloride copolymer. Examples of the diene polymer include butadiene polymer, isoprene polymer, chloroprene polymer, and butadiene / styrene copolymer. EPDM polymer, styrene / isoprene copolymer, etc. C, Japan wax, can be exemplified paraffin or the like, the natural resin, natural rubber, can be exemplified the rosin, the fats and a modified product thereof is preferable, the cured product can be exemplified solid fatty acids and metal salts.
A surfactant may be used together with the synthetic resin. The surfactant has a function of controlling elution of fertilizer components after application.
[0018]
The blended fertilizer of the present invention comprises a synthetic resin as a main component on the surface of core material particles containing a fertilizer as an active ingredient and having a circularity coefficient of 0.7 or more obtained from the formula shown below. It is a blended fertilizer in which one or more types of time-dissolved coated granular fertilizers that are covered with a film are contained as active ingredients.
Circularity coefficient = (4π × projection area of particle) / (length of contour of particle projection)²
The blended fertilizer of the present invention is not particularly limited in the other blends and the blending ratio thereof as long as one or more time-dissolved coated granular fertilizers are blended. It is preferable that the time-dissolved coated granular fertilizer is blended so that the fertilizer components are eluted in accordance with the nutrient absorption pattern of the crop.
[0019]
The nutrient absorption pattern of crops can be estimated by referring to the accumulated data in each prefecture's agricultural test site, each agricultural improvement extension station, and each farmer's farming guidance section. In general, the nutrient uptake pattern of a crop can be obtained from the difference between the nutrient uptake by season of the crop and the soil nutrient supply by season called geopower. In addition, the elution of the time-dissolved coated granular fertilizer of the present invention over time varies slightly depending on the area used, but can be estimated by the past monthly temperature of the area used.
The blended fertilizer of the present invention can be obtained by adjusting the nutrient absorption pattern and the elution over time of the time-dissolved coated granular fertilizer of the present invention in consideration of the accumulated data.
The soil temperature at this time is the temperature at a depth of 5 cm from the surface of the soil, but this soil temperature can be regarded as almost the air temperature, and can be substituted by the average air temperature during the cultivation period of the area. .
[0020]
In addition, each crop has its own nutrient absorption pattern, and the nutrients required for growth (nitrogen, phosphoric acid, potassium, etc.) are different. There is a limit to dealing with seed crops. If the time-dissolved coated granular fertilizer is applied in a large amount so that excessive fertilizer components are constantly eluted from the nutrient absorption pattern, it can be used alone, but the utilization efficiency is remarkably deteriorated.
Therefore, the blended fertilizer of the present invention combines two or more time-dissolved coated granular fertilizers having different elution start times and elution rates of the fertilizer components so as to elute according to the nutrient absorption pattern of the crop to be cultivated. Mix and adjust two or more types of time-dissolved coated granular fertilizers with different nutrients used as fertilizer ingredients, and adjust the blending so that the necessary nutrients of the crop to be cultivated will elute with growth Is preferred.
Moreover, you may mix | blend the coating fertilizer and chemical fertilizer different from this invention in the range which does not inhibit the effect of this invention remarkably.
[0021]
The cultivation method of the present invention comprises a synthetic resin as a main component on the surface of core material particles containing a fertilizer as an active ingredient and having a circularity coefficient of 0.7 or more obtained from the formula shown below. This is a method of using a blended fertilizer in which at least one type of time-dissolved coated granular fertilizer covered with a film is contained as an active ingredient.
Circularity coefficient = (4π × projection area of particle) / (length of contour of particle projection)²
[0022]
Although there is no limitation in particular in the usage method of the compound fertilizer of this invention, the whole quantity basic fertilization application method using a seedling box is the optimal.
The total amount-based fertilizer application method is a method in which the entire amount or most of the fertilizer components required during the cultivation period are applied to the seedling box at the start of seedling growth. Normally, the elution allowance of fertilizer components in crop seedlings is said to be 10-20 mg of nitrogen component per 100 ml of seedling culture soil, and if elution of fertilizer components exceeds this range, withering, puppet length etc. Concentration disturbance due to fertilizer components occurs. However, in the fertilization method (contact fertilization method) in which the roots of the crop and the fertilizer are in direct contact, as represented by the whole-basis fertilization method using a seedling box, the elution allowance is even smaller. That is, in the period from immediately after sowing to the middle stage of raising seedlings (1/2 of the whole raising period), even a slightly eluted fertilizer component causes damage.
However, when the compounded fertilizer of the present invention is used for the whole-basis fertilization method, the amount of fertilizer component elution from immediately after sowing to the middle stage of seedling can be extremely suppressed, so that the crop does not cause concentration problems. The roots rooted from the seed buds come into contact with the fertilizer as they grow, and finally become in a state of holding the fertilizer with the roots, and when the grown seedlings are transplanted into Honda, they are transplanted as they are. The fertilizer component can be directly absorbed from the fertilizer in contact with the fertilizer, and the utilization efficiency of the fertilizer can be greatly improved.
[0023]
【The invention's effect】
In the time-dissolved coated granular fertilizer of the present invention, the ratio of induction period / elution period is 0.2 or more, and the elution amount until half of the induction period after application is 1.0 wt% or less The fertilizer of the present invention has extremely excellent initial elution suppression function, and the fertilizer dissolution according to the nutrient absorption pattern of the target crop occurs, and the cultivation method of the present invention does not adversely affect the crop. It is a method that can remarkably improve work efficiency and fertilizer utilization efficiency.
[0024]
【Example】
EXAMPLES The present invention will be described below with reference to examples, but the present invention should not be limited by these examples. In the following examples, “%” is “% by weight” unless otherwise specified.
[0025]
Manufacture of core material particles
The core material raw material particles used as the raw material for obtaining the core material particles were obtained based on the flow sheet shown in FIG.
(Manufacture of core material raw material particle A)
50 kg of urea (8 mesh pass product) as raw material is supplied from hopper A, piston hydraulic pressure 270 kg / cm consisting of screw feeder B and roll press C²By supplying it to the roll compactor set to T (Alexander dry granulator, WP-400 * 330V type), it was set as flakes. Next, the flaky material was crushed with a crusher D, and then classified with a vibrating sieve E to obtain a primary product having a size of 6 to 8 mesh. At this time, the oversized product having a size larger than 6 mesh is guided again to the crusher D, and pulverization is repeated until it becomes smaller than 6 mesh. On the other hand, an undersized product having a size smaller than 8 mesh is returned to the hopper A and formed into a flake shape again. The primary product is stored in the flexible container F and used as the core material raw material particles A.
(Manufacture of core material raw material particle B)
Core material raw material particles B were obtained according to (Production of core material raw material particles A) except that the raw material was changed from urea to ammonium sulfate (8 mesh pass product).
(Manufacture of core material particle C)
Core material raw material particles C were obtained in accordance with (Manufacturing of core material raw material particles A) except that the raw material was changed from urea to potassium chloride (8 mesh pass product).
[0026]
Manufacture of core particles
(Manufacture of core particle A)
Core material raw material particles A are classified by vibrating sieve G shown in the flow sheet of FIG. 2 to obtain 7-8 mesh core material particles A, and the circularity coefficient of core material particles A is set to PIAS-IV manufactured by Pierce Co., Ltd. And measured. Measurement conditions were 50 threshold values 120-120 using 50 randomly extracted particles. Table 1 shows the measurement results of the circularity coefficient.
(Manufacture of core particle B)
The core material raw material particles A were subjected to a smoothing treatment with a rotating disk type granulator H (manufactured by Fuji Powder Co., Ltd., Malmerizer QJ230) until the circularity coefficient became 0.7 or more. The processing method is as shown in the flow sheet of FIG. 3. The core material particles A are weighed and supplied to the rotating disk type granulator H, and are squared under the following operating conditions, followed by classification with a vibrating sieve J. 7 to 8 mesh core material particles B were obtained. The circularity coefficient was measured according to (Production of core particle A). Table 1 shows the measurement results of the circularity coefficient.
Operating conditions
Driving method: Batch type
Operating time: 1 min
Eye plate pitch: 4 mm
Speed ratio: 0.3
Charge amount: 2kg (per time)
(Manufacture of core particle C)
Core material particles C were obtained in accordance with (Manufacturing of core material particles B) except that the operating time 1 min was changed to 5 min. The circularity coefficient of the obtained core material particles C was measured according to (Production of core material particles A). Table 1 shows the measurement results of the circularity coefficient.
(Manufacture of core particle D)
Core material particles D were obtained in accordance with (Manufacturing of core material particles B) except that the operation time 1 min was changed to 9 min. The circularity coefficient of the obtained core material particles D was measured according to (Production of core material particles A). Table 1 shows the measurement results of the circularity coefficient.
(Manufacture of core particle E)
Core material particle E was obtained in accordance with (Manufacturing of core material particle B) except that core material raw material particle A was replaced with core material raw material particle B and the operating time 1 min was changed to 5 min. The circularity coefficient of the obtained core material particle E was measured according to (Production of core material particle A). Table 1 shows the measurement results of the circularity coefficient.
(Manufacture of core particle F)
Core material particle F was obtained according to (Manufacturing of core material particle B) except that core material raw material particle A was replaced with core material raw material particle C and the operation time was changed to 1 minute for 5 minutes. The circularity coefficient of the obtained core material particles F was measured according to (Production of core material particles A). Table 1 shows the measurement results of the circularity coefficient.
[0027]
Production of time-dissolved coated granular fertilizer
(Manufacture of time-dissolved coated granular fertilizers 1-16)
The production of the time-dissolved coated granular fertilizer will be described with reference to the flow sheet of FIG. 1. The hot hot air is introduced into the jet tower 1 having a tower diameter of 250 mm, a height of 2000 mm, an air jet diameter of 50 mm, and a cone angle of 50 degrees. From the top to the top. The hot hot air is blown from the blower 10, passes through the orifice flow meter 9, is heated to a high temperature by the heat exchanger 8, flows into the jet tower 1, and from the exhaust gas outlet 3 installed at the upper part of the jet tower 1. Discharged. Inside the jet tower 1 in which the high-temperature hot air circulates, core material particles A to F shown in Table 2 (the core material particles 5 on the flow sheet) are installed on the side surface of the jet tower 1. 10 Kg is charged from the core material particle inlet 2 and the core particle 5 is caused to flow as shown in FIG. At this time, it is necessary to adjust the flow rate and hot air temperature appropriately for each sample. The flow rate is adjusted while measuring with an orifice flow meter, and the hot air temperature is determined as T1 hot air temperature, T2 granule temperature, and T3 exhaust gas. Adjust while measuring temperature. In each example, the flow rate (orifice flow meter 9) is 4 m.³/ Min, hot air temperature (hot air temperature T1) 100 ° C. ± 2 ° C.
On the other hand, each component of the coating material composition shown in Table 2 and toluene as a solvent are added to the dissolution tank 11 and mixed and stirred to obtain a 1.5 wt% uniform coating material mixed solution 12. The solution 12 is transported at a flow rate of 0.1 kg / min to the spray nozzle 4 which is a full-contained one-fluid nozzle with an opening of 0.8 mm, which is installed at the lower part of the jet tower 1 by the pump 6, and is a core material in flow The particles 5 are sprayed and sprayed. At this time, the dissolution tank 11 and the piping from the dissolution tank 11 to the spray nozzle 4 are made to have a double structure so that the temperature of the dissolution liquid 12 does not become 80 ° C. or lower, and the solution 12 is passed through steam. Was transported while warming.
The spraying process starts when the powder temperature T2 of the flowing core material particles 5 reaches a predetermined temperature, sprays for a predetermined time, performs drying for a predetermined time, and finishes drying. The blower 10 was stopped, and the coated core particles 5 were discharged from the outlet 7 at the bottom of the jet tower 1 to obtain time-dissolved coated granular fertilizers 1 to 16 shown in Table 2 (however, the time limit) The elution-type coated granular fertilizers 1 to 6 and 15 to 16 were sprayed with the coating material composition of the second layer after spraying the coating material composition of the first layer.
[0028]
(Dissolution test)
The time-eluting type coated granular fertilizers 1 to 16 obtained by the production of the time-eluting type coated granular fertilizer are each immersed in 200 ml of water in 10 g units and left to stand at 25 ° C. After a predetermined period, the fertilizer is removed from the water, and the fertilizer components eluted in the water are determined by quantitative analysis. After the measurement, the fertilizer is put in 200 ml of fresh water and allowed to stand at 25 ° C. After a predetermined period, the same quantitative analysis of fertilizer components is performed. Such an operation was repeated, and the elution rate curve was created by graphing the relationship between the total elution of fertilizer components eluted in water and the number of days. The result is shown in FIG. In addition, the number of days (induction period) from the start of soaking to 10 wt% elution is “D1”, and the number of days (elution period) until 80 wt% elution is “D2” thereafter, which is ½ of the induction period. The elution rate at the time point was set to “1/2 · D1”. The results are shown in Table 3. As is clear from the result of “1/2 · D1”, the time-dissolved coated granular fertilizer (2, 4, 6, 8, 10 to 10) obtained by using the core particles having a circularity coefficient of 0.7 or more. 14, 16) is the initial dissolution compared to the time-dissolved coated granular fertilizer (1, 3, 5, 7, 9, 15) obtained by using core particles having a circularity coefficient of less than 0.7. It can be seen that the amount is extremely small.
[0029]
(Adjustment of compound fertilizer for cucumber cultivation)
The nutrient requirement curve (the nutrient absorption pattern) of the cucumber during the period from sowing to harvesting in the outdoor cultivation of cucumber (variety: Asomidori) in Minamata-shi, Kumamoto Prefecture (place name) was measured in the same year last year. It calculated | required from the soil nutrient supply curve during the cultivation period (the said soil nutrient supply amount according to said period) and the nutrient absorption curve (the said nutrient absorption amount according to said period) of this cucumber. The basic data used to obtain these curves is the prototype data of the same crop that was implemented in the same area last year. The nutrient demand curve of the cucumber obtained in this way for the previous year is shown in FIG.
Next, combined fertilizer A having an elution curve that approximates the nutrient requirement curve was obtained by combining time-dissolved coated granular fertilizers 12 and 16. The blended fertilizer A has an elution curve No. shown in FIG. 12 and no. 16: 95: 5, 90:10... 5:95 The composition ratio is changed every 5 units, and a virtual elution curve obtained from each composition ratio is drawn. The composition ratio with the most approximate elution curve was chosen. As a result, it was found that the compounded fertilizer A is most suitable when the time-dissolved coated granular fertilizers 12 and 16 are combined at a ratio of 60:40. FIG. 5 shows an elution curve of the mixed fertilizer A as an example mixed fertilizer elution curve. Under the present circumstances, although this nutrient absorption curve is a curve which took in the temperature change (the range of about 18 degreeC-32 degreeC) during a cultivation period, since the average temperature during a cultivation period is about 25 degreeC, the elution curve of 25 degreeC 4 is used as the standard for specifying the composition ratio. Similarly, timed elution type coated granular fertilizers 7 and 9 were combined to obtain a mixed fertilizer B having an elution curve that approximated the nutrient demand curve. The compounded fertilizer B was found to be most suitable when the time-dissolved coated granular fertilizers 7 and 9 were combined at a ratio of 40:60. The elution curve of the mixed fertilizer B is shown in FIG. 5 as a comparative example mixed fertilizer elution curve.
From FIG. 5, in the compound fertilizer A which is the compound fertilizer of the present invention, the initial elution is suppressed to be extremely low, and the elution curve is very close to the nutrient requirement curve of cucumber, whereas the compound fertilizer of the present invention. In the mixed fertilizer B different from the above, the suppression of the initial elution is insufficient, and the elution curve is almost similar to the nutrient requirement curve of the cucumber, but it can be seen that the elution curve in the initial stage is clearly different. .
[0030]
(Cucumber cultivation test using compound fertilizer)
A cucumber cultivation test using compounded fertilizer A and compounded fertilizer B was conducted in a field in Minamata City, Kumamoto Prefecture (name of place). The cultivation test was conducted in three types of cultivation formats: a customary zone test based on a normal farm work format, an example zone test using the mixed fertilizer A, and a comparative zone test using the mixed fertilizer B. Details of each test are shown below.
Practice test
As a seedling fertilizer, 100 mg of nitrogen component (N component, hereinafter abbreviated as N), phosphorus component (P)₂O₅Component, hereinafter abbreviated as P. ) 10mg, potash component (K₂O component, hereinafter abbreviated as K. ) After filling 400 mg of a 10 cm-diameter plastic pot with 10 mg of mixed seedling material, seed one cucumber seed (variety: Aso Midori), and then cover the seedling culture with 4 seeds. I grew seedlings in a plastic pot from May 26th to May 6th. After raising the seedlings in the vinyl pot, the seedlings were transplanted in the field at a density of 1800 / 10a, and cultivation in the field was started. Thereafter, the harvesting of the main stem was started from July 6, the side branch was started from July 26, and the crop was harvested on September 20, and the cultivation was completed.
After the seedlings are transplanted into the field, the advanced chemical fertilizer containing 14% N, 14% P and 14% K as fertilizer components is fertilized in four times between the time the seedlings are planted in the field and harvested. did. The amount of fertilization was adjusted so that NPK would be 15Kg-15Kg-15Kg per 10 ares of field after four times of fertilization.
Example test
For 100 ml of seedling culture soil that does not contain any fertilizer prepared in advance, 400 ml of seedling culture material in which 10 mg of P and 10 mg of K are mixed as fertilizer for seedling and 8.33 g of N present in the mixed fertilizer A Stir well with compound fertilizer A in an amount of N (corresponding to 15 kg per 10 ares of field), fill in a 10 cm diameter plastic pot, and then seed one cucumber seed (variety: Aso Midori) Further, the seedling cultivating soil was covered thereon, and seedlings were grown in a plastic pot from April 26 to May 6. After raising the seedlings in the vinyl pot, the seedlings were transplanted in the field at a density of 1800 / 10a, and cultivation in the field was started. Thereafter, the harvesting of the main stem was started from July 6, the side branch was started from July 26, and the crop was harvested on September 20, and the cultivation was completed.
The seedlings were transplanted into the field, and the advanced chemical fertilizer containing 14% of P and 14% of K as fertilizer components was fertilized in four times between the time when the seedlings were planted in the field and before harvesting. The amount of fertilization was adjusted so that P-K would be 15 Kg-15 Kg per 10 ares of the field after four times of fertilization.
Comparative example test
For 100 ml of seedling culture soil that contains no pre-adjusted fertilizer, 400 ml of seedling culture material in which 10 mg of P and 10 mg of K are mixed as a fertilizer for seedling and 8.33 g of N present in the mixed fertilizer B Mix well with fertilizer B in an amount that makes N (corresponding to 15 kg per 10 ares) and fill a 10 cm diameter plastic pot, then seed one cucumber seed (variety: Aso Midori) Further, the seedling cultivating soil was covered thereon, and seedlings were grown in a plastic pot from April 26 to May 6. After raising the seedlings in the vinyl pot, the seedlings were transplanted in the field at a density of 1800 / 10a, and cultivation in the field was started. Thereafter, the harvesting of the main stem was started from July 6, the side branch was started from July 26, and the crop was harvested on September 20, and the cultivation was completed.
The seedlings were transplanted into the field, and the advanced chemical fertilizer containing 14% of P and 14% of K as fertilizer components was fertilized in four times between the time when the seedlings were planted in the field and before harvesting. The amount of fertilization was adjusted so that P-K would be 15 Kg-15 Kg per 10 ares of the field after four times of fertilization.
[0031]
As described above, N fertilization was performed in the conventional test, and cucumber was cultivated without N fertilization in the comparative example test and the example test.
As a result, germination did not occur at all in the comparative example test (germination rate 0%). This is apparently due to excessive elution of fertilizer components at the early growth stage. As is apparent from the comparative example compound fertilizer elution curve of FIG. 5, in the compound fertilizer B, the initial elution was not sufficiently suppressed, and this excessive elution caused a concentration disorder on the cucumber seeds.
On the other hand, in the example group test, the germination rate was 97%, which was a good growth state almost equal to the germination rate of 98% in the customary group test.
In addition, the harvest index in the test in the example section was 102, while the yield in the conventional section was set to 100, which was a yield that was not inferior to that in the conventional section test in which N additional fertilization was performed. Thus, it was found that, in the example zone test, a yield equal to or higher than that obtained even if the fertilizer was reduced by about half of the conventional zone test (conventional farm work). If the cultivation method of fertilizing the compounded fertilizer of the present invention at the same time as sowing is used, labor saving and the utilization efficiency of the fertilizer can be greatly improved.
[0032]
[Table 1]

[0033]
[Table 2]

[0034]
[Table 3]

[Brief description of the drawings]
[Fig. 1] Flow sheet of spouted bed
Fig. 2 Flow sheet of compression granulation method
Fig. 3 Flow sheet of smoothing method
Fig. 4 Dissolution rate curve of time-dissolved coated granular fertilizer (5-9, 12, 15, 16)
Fig. 5 Nutrient requirement curve of cucumber and each elution curve of compounded fertilizers A and B
[Explanation of symbols]
1. Spout tower
2. Core particle inlet
3. Exhaust outlet
4). spray nozzle
5. Core particle
6). pump
7). Outlet
8). Heat exchanger
9. Orifice flow meter
10. Blower
11. Dissolution tank
12 Coating material mixed solution
T1. Hot air temperature
T2. Particle temperature
T3. Exhaust gas temperature
SL. steam
A. hopper
B. Screw feeder
C. Roll press
D. Crusher
E. Vibrating sieve
F. Storage unit (Flexible container)
G. Vibrating sieve
H. Rotating disk type granulator
J. et al. Vibrating sieve

Claims

A film containing synthetic resin as a main component is covered on the surface of core particles containing fertilizer as an active ingredient and having a circularity coefficient of 0.7 or more obtained from the calculation formula shown below. Time-eluting type coated granular fertilizer characterized by
Circularity coefficient = (4π × projection area of particle) / (length of contour of particle projection) ²

A blended fertilizer comprising at least one type of time-dissolved coated granular fertilizer according to claim 1 as an active ingredient.

A cultivation method using the fertilizer according to claim 2.