EXAMINING THE IMPACT OF PULSE CROPS ON QUALITY OF SOIL IN WHEAT-BASED, RAIN-FED CROPPING SYSTEM ON THE BROWN SOILS
Improving soil quality with the inclusion of pulse crops in wheat-based cropping systems may help producers to develop appropriate sequences for crop rotations with improved resource using efficiency. The objective of this study is to examine selected physical, chemical and biological soil quality attributes of pulse crops with shallow and deep root systems grown in wheat-based, semi-arid, rain-fed conditions. The study was conducted at Brooks, AB using field pea (Pisum sativum L.), chickpea (Cicer arietinum L.) and lentil (Lens culinaris Medikus) grown alternately with wheat. A fourth rotation treatment included lentil and chickpea alternated with wheat (lentil-wheat-chickpea-wheat). All rotations with the pulse crops were compared to continuous wheat. Soils were sampled from three depths (0-15, 15-30 and 30-60 cm) in the spring of 2017 and 2018, after six and seven years of the rotation were complete. Continuous wheat enhanced the formation of macro-aggregates (>6.35 mm) and pulse crop rotations enhanced the formation of micro and meso-aggregates (1.00-0.50 mm and 0.50-0.15 mm). All of the rotations had similar fall soil moisture, soil microbial biomass, microbial community composition, total soil carbon, nitrogen and soil organic carbon at all soil depths. On a mass basis, only about 0.5 to 1.5 % of the soil organic matter was in the light fraction organic matter (LFOM). Chickpea alternated with wheat had the highest amount of LFOM and potential mineralizable nitrogen (PMN) in both sampling years. Pulse crop rotations collectively had higher LFOM and PMN values than continuous wheat in both years. Wheat alternated with field pea had the highest 1000-kernel weight, without affecting seed yield. The inclusion of grain legumes with different rooting depths into wheat-based cropping systems did not influence overall soil quality in the short time frame of this study. However, this study provides a baseline for the evaluation of the effect of inclusion of pulse crops into wheat-based cropping systems soil quality while emphasizing the importance of the subsequent wheat crop productivity.
Pulse crop rotations, Soil quality, Continuous wheat, Cropping systems
Master of Science (M.Sc.)