Management practices for black lentil green manure for the semi-arid Canadian prairies

Previous research with lentil (Lens culinaris Medic.) green manure in the s emiarid prairies of western Canada has indicated that water use by the gree n manure crop often reduces grain yield of the succeeding cereal crop compa red to those obtained after conventional summerfallow. In this study, we ev aluated several green manure management practices that have potential to tr ap snow and enhance overwinter soil water recharge. These practices include d: using herbicides to halt the growth of the green manure crop thus elimin ating the need for soil incorporation, planting mustard (Sinapis alba L.) s trips after incorporation, and leaving standing strips of non-incorporated lentil. Our results showed that none of the green manure management strateg ies increased wheat (Triticum aestivum L.) yield or grain protein concentra tion compared to wheat grown on conventional summerfallow. Leaving strips o f standing lentil during bud stage incorporation provided barriers for wind erosion protection, while not decreasing wheat yield or protein content. G lyphosate or 2,4-D amine applied at bud stage of the lentil, and without so il incorporation, reduced available soil N. However, 2,4-D did not halt pla nt growth and water use quickly enough to avoid reducing yield of the succe eding wheat crop, while glyphosate generally halted water use more rapidly. The inability of the green manure management strategies to increase wheat yields over that obtained from conventional summerfallow was because the so il rooting zone is typically filled to capacity with water by this latter p ractice under the prevailing soil and climatic conditions. If green manurin g is practised, early incorporation with lentil leave strips is the most pr omising management system. However, even with improved water management pra ctices, green manuring did not demonstrate a consistent advantage over summ erfallow, which may be required to offset the added economic costs required to enact this practice.