Soil water conservation under zero- and conventional tillage systems on the Canadian prairies

This work investigated the soil water balance under different tillage systems and the effect of spring nitrogen and water levels on crop yields in the Canadian Prairies. Results from 12 site-years indicate that soil water recharge during the autumn to seeding period was greater under zero tillage than under conventional tillage, probably due to reduced soil water evaporation during the period from snow-melt to seeding. Water use efficiency was 49.7 kg ha −1 wheat per cm water under conventional tillage. Under zero tillage, water use efficiencies varied with soil texture, ranging from 53.7 to 186 kg ha −1 wheat per cm water for loam and heavy clay, respectively. Wheat yield was well correlated with both available nitrogen and water content in spring. Nitrogen was more limiting under zero tillage than under conventional tillage. The crop response to available nitrogen was two times greater under zero tillage compared with conventional tillage. Soil water was more limiting under conventional tillage than under zero tillage. The crop response to soil moisture content was four times greater under conventional tillage compared with zero tillage. Soil water depletion during the growing season essentially followed the same pattern under both tillage systems.