Long-Term Cotton Yield Impacts from Cropping Rotations and Biocovers under No-Tillage

Sustaining crop yields assumedly entails crop rotations and biocovers. To test this, cropping sequences and biocover effects on cotton (Gossypium hirsutum L.) yields were assessed under long-term no-tillage. Main plots were eight cropping sequences of cotton, corn (Zea mays L.), and soybean (Glycine max L.) on a Loring silt loam at the Research and Education Center at Milan, TN. Sequences were repeated in 4-yr cycles (i.e., Phases I, II, and III) from 2002 to 2013. Split-plots were biocovers, which consisted of hairy vetch (Vicia villosa L.), Austrian winter pea (Pisum sativum L. sativum var. arvense), wheat (Triticum aestivum L.), poultry litter, and fallow control. Continuous cotton had greater yield than cotton grown in rotations [3.1 and 2.8 Mg ha-1, respectively; p = 0.02 (averaged across biocovers and phases)]. Biocover did not increase yield in continuous cotton (p > 0.05). However, various cropping sequences did result in higher yield than continuous cotton within 4-yr cycles. Specifically, corn-corn-soybean-cotton rotations were highest yielding during Phase II (4.0 Mg ha-1), which was equivalent to cotton-corn-cotton-soybean (3.5 and 3.8 Mg ha-1, respectively); and cotton-corn-cotton-corn during Phases II and III (3.6 and 3.8 Mg ha-1, respectively). All aforementioned rotations increased yield above continuous cotton during Phases I and III (p < 0.05). Results indicate increasing cropping diversity with one and two years of soybean or corn, respectively, in a 4-yr cycle maintains cotton seed yield long-term.