Landscape Management of Agronomic Processes for Site-specific Farming

Precision management of agricultural land has the potential to improve crop production and environmental protection by harmonizing inputs with crop requirements at the sub-field level. Fertilizer use efficiency across a field can be quite variable. The objective of this project is to measure and model landscape dynamics for a hummocky topography in the Black Soil Zone of east central Alberta. Soil moisture and temperature dynamics were measured using automated sensors and data loggers. Soil nutrients, crop growth, and crop nutrient uptake dynamics were monitored at three landscape positions (shoulder, back slope, and foot slope positions).

This was the fifth year at this field site. Climatic conditions were slightly below normal with 9 in. of growing season precipitation, but much better than most of the province which suffered through a drought. However, when combined with low snow precipitation during the winter, moisture conditions had a significant impact on crop growth and nutrient uptake. Throughout the growing season, the highest yielding areas of the field were the lower slope positions, while the lower yields were in the upper slope positions. Nutrient analysis of the barley crop biomass indicated that by anthesis, 80-95 percent of the total nitrogen (N) at harvest was in the above-ground biomass. This compared to 50-70 percent for phosphorus (P), 90-100 percent for potassium (K), and 80-90 percent for sulfur (S). In addition, by anthesis the crop on the moisture limited upper slope positions had absorbed and translocated enough nutrients to satisfy the lower yield potential, while the lower slope positions were still absorbing and/or translocating nutrients well past this stage. At harvest, the yield pattern remained the same, with highest yield and nutrient content of grain and straw in the lower slope positions. Ultimately, crop growth, soil nutrient dynamics, and crop uptake of nutrients vary with the differences in the moisture and temperature regimes among the landscape positions. The results of this study will be used to help make fertilizer recommendations based on production potential and nutrient supply of variable landscapes. AB-19