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Project Background Success of No-till Soybeans
One of the most significant changes in the Ontario agricultural landscape in the last 15 years has been the relatively widespread adoption of no-till practices within soybean production. The economic and environmental benefits returning to producers and to the province as a result of conservation tillage soybeans may now exceed 30 million dollars annually. Expansion of no-till soybean acreage has been relatively constant throughout the late 1980s and much of the 1990s. However in the last few years, despite an impressive history of success, no-till soybeans have been viewed less optimistically. Expansion of new no-till acres seems to be stalled and in some cases traditional no-till soybean acres have reverted back to more intensive tillage systems.
Fertility Management in Reduced Tillage Systems
No-till or reduced tillage systems virtually eliminate soil inversion or mixing. This fact has often lead to concerns that immobile nutrients such as phosphorous or potassium could become stratified into zones of high concentration near the soil surface and zones of depletion at greater depths within the rooting profile. Historically, nutrient stratification has not been deemed as a limitation to no-till soybean cropping systems in Ontario. Recommendations have generally revolved around the concepts that soybeans were good scavengers of nutrients and that they generally did not respond to starter fertilizer placement. Both producers and equipment suppliers found that not having to deal with fertilizer handling and placement issues made the no-till soybean system even more attractive and thus the vast majority of soybean planting equipment was not equipped to apply fertilizer.
Dr. Tony Vyn and the Cropping System group at the University of Guelph have done some detailed soil measurements on fields in Ontario that had been in no-till for 5-15 years and found extensive potassium stratification. This work focused mainly on how to manage potassium for corn production. Their results indicated that no-till corn yields could be significantly enhanced by banding potash through the corn planter on these long term no-till fields when soil test levels for K were less than 112 ppm.. In addition, they have shown some positive responses in soybean yields both as a result of enhanced K application in the previous corn crop, and as a result of banding K at the time of soybean planting. |
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