Effect of Long-Term Cropping System Management on Crop Yield and Soybean Cyst Nematode.

There has been an increase in the implementation of conservation practices in the highly erodible soils of Missouri. When combining use of cover crops with conservation tillage, cover crops have been shown to improve productivity of degraded soils. The objectives of this research were to evaluate the effect of long-term cropping system management on yields and soybean cyst nematode (Heterodera glycines) egg population densities. This long-term cropping systems site was initiated in 1994 near Novelty, MO. Treatments included a corn-soybean-wheat rotation with three tillage/cropping systems: 1) no-till corn-soybean-wheat with double crop soybean (DC), 2) no-till corn-soybean-wheat with frost-seeded red clover cover crop (FSC), and 3) reduced-till corn-soybean-wheat (RT). Each crop and cropping systems were represented each year in nine large plots (9.1 by 90 m). The reduced tillage treatment included fall chisel plowing before corn and/or soybean followed by a field cultivator, disk, or finishing tool in the spring, while a field cultivator, disk, or finishing tool is utilized prior to planting wheat. Soil was sampled to a 15 cm depth to evaluate soil chemical properties and SCN egg population densities. Crops were managed for cost-effective high yielding systems. Significant differences in corn (Zea mays L.) yields occurred in 1995-96, 2000, 2002, 2004-10, and 2015-16 with the highest yielding treatments including 6 RT, 4 DC, and 2 FSC. Significant differences in soybean [Glycine max (L.) Merr.] yield occurred in 2002, 2006, and 2016 with the highest yielding cropping system being 2 DC and 1 RT. Significant differences in wheat (Triticum aestivum L.) yield occurred in 2008-9, 2011, and 2014 with four RT systems being the highest yielding.