The Effects of Soybean Density and Sowing Time on the Yield and the Quality of Mixed Silage in a Corn and a Soybean Strip Intercropping System

Abstract

Intercropping is a cropping strategy that makes efficient use of space, nutrients, and soil. A 2-year field trial was conducted in 2019 and 2020 to study the effects of different soybean sowing times (9 days before corn sowing (ST1), 0 days at corn sowing (ST2), and 9 days after corn sowing (ST3), respectively) and densities (120,000 plants ha−1 (PD1), 150,000 plants ha−1 (PD2), and 180,000 plants ha−1 (PD3), respectively, and the planting density of corn was 60,000 plants ha−1 constantly) on total yield and on mixed silage quality in a corn and a soybean strip intercropping system. The yield decreased with an increase in soybean planting density. Before ensiling, the total dry matter (DM) content increased with an increase in soybean planting density, while that of crude protein (CP) content decreased with sowing time. The interaction of planting density × sowing time was significant for NDF and WSC content. After ensiling, the WSC content of PD2ST3 (4.90% DM) was the highest. The PD1 (4.51%) had a higher content of ammonia–nitrogen to total nitrogen than that of PD2 and PD3. The lactic acid content of PD2ST3 (3.14% DM) was the highest. In general, better silage quality and a higher total yield were obtained when soybean was sown at the planting density of 150,000 plants ha−1 after 9 days of corn sowing.