Papers by Wim Van Averbeke
... John Sender (School for Oriental and African Studies, United Kingdom) Prof ... All ARDRI staf... more ... John Sender (School for Oriental and African Studies, United Kingdom) Prof ... All ARDRI staff was engaged in this research, including Wim van Averbeke, acting director at the time, Peter Scogings, Mthozami Goqwana, Joyce Mafu, Patrick Masika, Thembakazi Nqodi, Msigisi Mbuti ...
Bookmarks Related papers MentionsView impact
Communications in Soil Science and Plant Analysis, 2011
Bookmarks Related papers MentionsView impact
Communications in Soil Science and Plant Analysis, 2012
Bookmarks Related papers MentionsView impact
Agrekon, 1999
Bookmarks Related papers MentionsView impact
Agrekon, 1997
Bookmarks Related papers MentionsView impact
Soil Use and Management, Jan 1, 2006
Abstract. Hierarchical crop growth models can contribute significantly to land quality research b... more Abstract. Hierarchical crop growth models can contribute significantly to land quality research because the yield gap between the estimated optimum and the actual crop production has been identified as a major land quality indicator. This study describes a three-level, hierarchical crop production model, simulating radiation-thermal, water-limited and natural production potentials of annual crops. Input requirements have been kept low to ensure its applicability to developing regions, which often have access only to limited data. The simplicity of this model also has disadvantages: inconsistencies have been reported when applying this model in semiarid regions, which are characterized by very irregular rainfall patterns. Revision of the water balance, which simulates the availability of water, was required. The modified model was validated using the experimental yields of maize and sunflower in Guquka, a semiarid region of South Africa. Yields were estimated very well, possible improvements to crop production were identified and implications for land-use planning highlighted. Yield gap analysis revealed that radiation, sunshine and temperature are favourable for crop production, but the heavy dependence on rainfall makes the region very vulnerable to drought, with devastating impact on yields. The generally low chemical soil fertility further reduces crop performance.
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Bioresource Technology, Jan 1, 2010
Understanding the dynamics of N forms applied as manure is germane for appropriate rate and timin... more Understanding the dynamics of N forms applied as manure is germane for appropriate rate and timing of applications of manure. Manure characterization and laboratory incubation were conducted for 120 days to study the mineralization of poultry, cattle and goat manures. Results showed that manure properties differ. Net immobilization of N was recorded for goat and cattle manures while poultry manure mineralized marginally. The relationship between N release and time is polynomial (cubic). The release phases were: initial rapid N release at 0–30 days; phase of constant release; 40–55 days; decline phase in N release 70–90 days and sharp increase in N release at 120 days. Increasing the N rates of manures above 120 kg N ha−1 will improve their potential as plant nutrient sources. Complementing the manures with inorganic N fertilizers in integrated nutrient management will also improve its quality and effectiveness.
Bookmarks Related papers MentionsView impact
Bioresource Technology, Jan 1, 2010
Laboratory incubation was conducted for 120Â days to study the fate of phosphorus in poultry (PM),... more Laboratory incubation was conducted for 120Â days to study the fate of phosphorus in poultry (PM), cattle (CM) and goat manures (GM). Phosphorus mineralized from manure was dependent on total P, Al and Fe content. Manures improved P availability in the order: PMÂ >Â CMÂ >Â GM; however, the highest amount of P was fixed or immobilized between 10 and 70Â days of incubating with CM and GM. Fixation and immobilization of mineralized P from poultry manure was negligible probably due to the high total P and the low amount of Al and Fe. Generally, manure application reduced the ability of the soil to fix P. More than 90% of the manure P was either immobilized or fixed by the soil. The relationship between the amount of P released and time was cubic. Improvement of the C:P ratio of CM and GM would be an option to enhance their agronomic use as fertilizer P source.
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Bioresource Technology, Jan 1, 2010
Crop responses to different manures differs considerably, however, the factors responsible for it... more Crop responses to different manures differs considerably, however, the factors responsible for it have not been conclusively elucidated. Consequently, this study examined the biomass response of Cucurbita maxima and Solanum retroflexum to application rates of chicken and kraal manures of cattle and goat, and soil factors related to salinity. The crops’ biomass yield increased linearly with increase in application rates of kraal and chicken manures, but steeper in the latter. Results showed that significant decline in biomass yield in chicken manure at rates above 8.5 tons ha−1 were not due to salinity. The crops’ response to cattle and goat kraal manures was linear but polynomial (cubic) in layer chicken manure. It was concluded that the yield decline in chicken manure was due to other manure factors except salinity, probably toxicity effect of the manure fatty acids. Further research was however, recommended to elucidate this claim.
Bookmarks Related papers MentionsView impact
Agrekon, Jan 1, 1997
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Agrekon, Jan 1, 2006
Bookmarks Related papers MentionsView impact
Communications in Soil Science and Plant Analysis, Jan 1, 2005
... Table 4. Selected chemical properties of garden and field soils from two wards in the former ... more ... Table 4. Selected chemical properties of garden and field soils from two wards in the former Ciskei region of South Africa Soil property Guquka Koloni ... 2438 Page 9. observed in many cultivated soils in other parts of South Africa (Scotney and Dijkhuis 1990; Du Toit et al. 1994). ...
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Uploads
Papers by Wim Van Averbeke