Legume Crops Effects on Nitrogen Availability to Subsequent Corn in Organic Farming.

Legume Crops Effects on Nitrogen Availability to Subsequent Corn in Organic Farming.

Adrien N'Dayegamiye, Paul Deschênes, Caroline CÃxté, and Myléne Généreux

Research and Development Institute for the Agri-Environment (IRDA), 2700 Einstein, Complexe scientifique, D.1.110, Qc, Canada, G1P 3W8335 Vingt-Cinq East Road, Saint-Bruno-de-Montarville (Québec) Canada, J3V 0G7

Legume crops may increase soil nitrogen (N) availability to subsequent crops in organic farming. A five years study (2012-2016) was conducted in Saint-Bruno-de-Montarville , eastern Canada, to evaluate the N supply from legume crops, dairy cattle manure and compost to subsequent corn (Zea mays L.) under soil moldboard plowing or disc harrowing. Seven legume crops were cultivated in 2012 and 2014: crimson clover (Trifolium incarnatum L.), white clover (Ladino), red clover, white and red clover mix, hairy vetch (Vicia villosa Roth) in association with barley, alfalfa (Medicago sativa L.) and dry pea (Pisum sativum L.). Organic fertilizers (dairy cattle manure or commercial compost) were applied in fall at 30 Mg ha^-1 (on wet basis) prior to soil tillage using moldboard or offset disc. Compared with barley as control, legume crops significantly increased corn yield by 22 to 138 % and N uptake by 21 to 147 % in 2015. Corn yield and N uptake were highest for hairy vetch, white and red clover mix, red clover and white clover. Those legume crops also presented highest N use efficiency (13 to 54 %), with N credits to corn ranging from 20 to 41 kg N ha^-1. Corn yield and N uptake also were significantly increased by manure and compost application and by soil moldboard plowing. Nitrogen use efficiency varied from 17 to 31% and from 16 to 24% for cattle manure and compost, respectively. Corn N use efficiency from the studied organic sources was significantly increased by soil moldboard plowing compared with offset disc harrowing. Results of this study showed that legume crops must be completed with manure or compost to achieve optimum corn yields and N nutrition.

Keywords: legume crops, dairy cattle manure and compost, N use efficiency, tillage regime, corn yield and N nutrition, organic farming.