Can Leguminous Cover Crops Partially Replace Nitrogen Fertilization in Mississippi Delta Cotton Production?

Abstract EN

Petroleum prices impact cotton nitrogen (N) fertilization cost.

A field study was conducted from 2005 to 2007 to assess the interactions of cover crop (none, Austrian winter pea (Pisum sativum spp.

arvense) or hairy vetch (Vicia villosa Roth)) and N fertilization (0, 67 or 134 kg N/ha applied at planting) on N availability and cotton yield under reduced-tillage management.

Nitrogen content in desiccated residues averaged 49, 220, and 183 kg N/ha, in no cover crop, Austrian winter pea, and hairy vetch, respectively.

Seventy percent of N in the above ground cover crop was derived from biological N fixation.

In 2005, cover crops decreased cotton yield, while fertilizer N had no effect.

In 2006, cover crops did not affect yield, but yield was positively correlated with N rate.

In 2007, in no N plots, cotton yields were 65% higher in cover crops than in no cover crop.

However, yield from N fertilized cover crop plots were similar to N fertilized no cover plots.

These results indicate that leguminous cover crops can provide over 150 kg N/ha, but this N may not be as effective as fertilizer N for lack of synchronization between cotton N requirements and N release from residues.