No-Till Corn/Soybean Systems Including Winter Cover Crops

The use of winter cover crops (WCC) such as hairy vetch (Vicia villosa Roth) and cereal rye (Secale cereale L.), in a corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] rotation provides long-term benefits that are generally overlooked. There is a particular lack of information regarding the effects of WCC on soil physical and chemical properties. The objective of this study was to assess the effects of four crop sequences (C/S, corn-fallow/soybean-fallow; C-R/S-R, corn-rye/soybean-rye; C-R/S-V, corn-rye/soybean-vetch; and C-R/S-VR, corn-rye/soybean-vetch and rye) under no-till on several soil physical and chemical properties. Soil chemical properties included soil organic matter (SOM), pH, total nitrogen (TN), nitrates (NO₃–N), and available phosphorus (P). The analyzed soil physical properties analyzed were: water-aggregate stability (WAS), bulk density (Db), penetration resistance (PR), total porosity (TP), pore-size distribution, water retention properties, and saturated hydraulic conductivity (K ₛₐₜ). The experimental design was a split-split-plot where whole-plot treatments (sampling period) had a Latin square design and subplot treatments (crop sequences) were arranged in a randomized complete block design with four replications. Compared with winter fallow, crop sequences that included WCC provided substantial benefits from the soil productivity standpoint. Specifically, the use of the C-R/S-V or C-R/S-VR increased SOM down to 30 cm. All WCC sequences improved WAS with increases of 9, 13, and 17% for C-R/S-R, C-R/S-V, and C-R/S-VR, respectively. Winter cover crop sequences reduced Db and PR of the soil surface and increased total and storage porosity along with plant available water. While the C-R/S-V sequence was the most effective in reducing soil NO₃–N, the C-R/S-R sequence was the most effective in fixing soil P.