Impact of Cropping Sequence and Tillage System on Response to P Fertilization in Durum Wheat and Soybean

A study done to improve our ability to predict when P starter fertilizer is required by crops and identify management practices and fertilizer sources that may improve early season P availability to crops.


01 Feb 2007

2006 Annual Interpretive Summary

Impact of Cropping Sequence and Phosphorus Fertilization on Cadmium and Zinc Accumulation in Soybean and Durum Wheat, 2006

Crop sequence and tillage system can influence nutrient availability and response of crops to fertilizer applications, through effects on nutrient cycling, microbial population, soil temperature, and root growth. Therefore, optimum P fertilizer management may change with management practices as well as with crop type. The study evaluates the effects of cropping sequence and tillage practices on yield and quality response of durum wheat and soybean to different forms and placements of P fertilizer.

Phosphorus fertilization increased the biomass yield in durum wheat, but not in soybean. The source of P used did not affect the biomass response. Final grain yield was not affected by P application or P source in either durum wheat or soybean, indicating that grain yield was limited by factors other than P supply. Mycorrhizal colonization in durum wheat was not affected by P fertilization, but was highest when durum wheat was grown under reduced tillage following flax, and lowest when grown under conventional tillage following canola. There was also an interaction between tillage system and preceding crop on biomass and grain yield, with both soybean and durum wheat generally producing higher yields after flax than after canola under reduced tillage, but lower yields after flax than canola or barley under conventional tillage. The effect of preceding crop and tillage was greatest on the silty clay soil. The reasons for the tillage by preceding crop interaction are not apparent, but nutrient analysis of the crops may help to clarify some of the factors causing the yield response. It is possible that the increased mycorrhizal colonization due to the combination of reduced tillage after flax may encourage nutrient uptake and improve crop performance on the silty clay soil. MB-20F