Legume cover crop: a satisfactory organic N source for grain corn in S Ontario

Citation

Xueming Yang et al. 2018. Legume cover crop: a satisfactory organic N source for grain corn in S Ontario. 17th World Fertilizer Congress, Shenyang, China, Sept 2-7, 2018.

Résumé en langage clair

Soybean-winter_wheat-corn rotation is common for grain growers in humid southern Canada. There are two fallow periods in this rotation, one from wheat harvest (late July) to the following corn planting (May in next year). Fallow bears a high risk for nutrients leaching from the crop root zone into the water systems, eventually into the Great Lakes in the region. We aim to include a legume season into rotation after wheat harvest and to determine the amounts of nitrogen in cover crops, the reduction of residual soil mineral nitrogen before dominant overwinter leaching season, and nitrogen credit to the following crop corn.

The experiment was conducted on a sandy loam soil at Harrow, Ontario, Canada where annual average temperature and annual average precipitation are 9.2 degree C and 825 mm, respectively. Winter-hardy legumes used in this study were crimson clover, hairy vetch, and red clover. Two non-cover crop controls, a conventional control (170 kg N/ha fertilizer) and a zero control (0 kg N/ha fertilizer), were also included. This study reports the data collection from 2013-2017.

Crimson clover, hairy vetch and red clover are viable post winter wheat cover crops in southwestern Ontario as they establish reasonably well and are winter-hardy. Before freeze-up (early Dec), legume cover crops accumulated 150 kg/ha more N (biomass N) than no cover crop controls, and they reduced residual soil nitrogen by 50 kg N/ha relative to the conventional control. Legumes refreshed and scavenged more N (250-300 kg N/ha) in following spring, and the legumes were plowed down in early May as a sole N source for corn in the legume treatments. The corn yields were 14 ton/ha for the fertilized control and only 6 ton/ha for the un-fertilized control; in comparison, the corn yields were 12, 13 and 13 tons/ha for crimson clover, hairy vetch, and red clover treatments, respectively. Winter-hardy legumes could be important non-fertilizer N sources for corn in soybean-winter wheat-corn rotation.

Résumé

Soybean-winter_wheat-corn rotation is common for grain growers in humid southern Canada. There are two fallow periods in this rotation, one from wheat harvest (late July) to the following corn planting (May in next year). Fallow bears a high risk for nutrients leaching from the crop root zone into the water systems, eventually into the Great Lakes in the region. We aim to include a legume season into rotation after wheat harvest and to determine the amounts of nitrogen(N) in cover crops, the reduction of residual soil mineral N (RSN) before dominant overwinter leaching season, and N credit to the following crop corn.
The experiment was conducted on a sandy loam soil at Harrow, Ontario, Canada (421’38N, 8254’33W) using a randomized complete block design with four replications. Annual average temperature and annual average precipitation are 9.2 C and 825 mm, respectively. Winter-hardy legumes used in this study were crimson clover(CC), hairy vetch(HV), and red clover(RC). Two non-cover crop controls, a conventional control (CKC, 170 kg N ha-1) and a zero control (CKO, 0 kg N ha-1), were also included. This study reports the data collection from 2013-2017.
CC, HV and RC are viable post winter wheat cover crops in southwestern Ontario as they establish reasonably well and are winter-hardy. Before freeze-up (early Dec), legume cover crops scavenged 150 kg N ha-1 more N (biomass N) than no cover crop controls, and they reduced RSN by 50 kg N ha-1 relative to the conventional control. Legumes refreshed and scavenged more N (250-300 kg N ha-1) in following spring, and the legumes were plowed down in early May as a sole N source for corn in the legume treatments. The corn yields were 14 Mg ha-1 for the CKC and only 6 Mg ha-1 for the CKO; in comparison, the corn yields were 12, 13 and 13 Mg ha-1 for CC, HV, and RC treatments, respectively. Winter-hardy legumes could be important non-fertilizer N sources for corn in soybean-winter wheat-corn rotation.