%0 Journal Article
%T Legume Green Manure and Intercropping for High Biomass <i>Sorghum</i> Production
%A Clark B. Neely
%A Francis M. Rouquette Jr.
%A Cristine L. S. Morgan
%A Frank M. Hons
%A William L. Rooney
%A Gerald R. Smith
%J Agricultural Sciences
%P 605-621
%@ 2156-8561
%D 2024
%I Scientific Research Publishing
%R 10.4236/as.2024.156034
%X Before the advent of cheap, synthetic fertilizers, legumes were commonly used as green manure crops for their ability to fix atmospheric nitrogen (N). A three-year study at Overton, TX examined legume integration into high-biomass <i>sorghum</i> (<i>Sorghum</i><i> bicolor</i> L.) production systems on a Lilbert loamy fine sand recently cultivated after a fertilized bermudagrass [<i>Cynodon dactylon</i> (L.) Pers.] pasture. In this split-split plot design, &#8216;Dixie&#8217; crimson clover (<i>Trifolium incarnatum </i>L.) and &#8216;Iron and Clay&#8217; cowpea (<i>Vigna ungu</i><i>i</i><i>culata</i> L.) were integrated into a high-biomass <i>sorghum</i> production system to evaluate impacts on N concentration, C concentration, and yield of high-biomass <i>sorghum</i> and their impacts on soil total N and soil organic carbon (SOC). Main plots were split into crimson clover green manure (CLGM) and winter fallow (FALL) followed by three sub-plots split into warm-season crop rotations: cowpea green manure (CPGM), cowpea-<i>sorghum</i> intercrop (CPSR), and <i>sorghum</i> monocrop (SORG). Three N fertilizer treatments (0, 45, 90 kg N&#8729;ha<sup>&#8722;</sup><sup>1</sup>) were randomized and applied as sub-sub plots. The CLGM increased (<i>P</i><i> </i>< 0.01) <i>sorghum</i> biomass yield (16.5 t DM&#8729;ha<sup>&#8722;</sup><sup>1</sup>) 28% in year three but had no effect in the first two years. The CPSR treatment reduced <i>sorghum</i> yield up to 62% compared to SORG; whereas CPGM increased <i>sorghum</i> yield 56% and 18% the two years following cowpea incorporation. Rate of N fertilizer had no effect on <i>sorghum</i> biomass yield. Decrease in SOC and soil N over time indicated mineralization of organic N and may explain why no N fertilizer response was observed in <i>sorghum</i> biomass yield. Cowpea showed strong potential as a green manure crop but proved to be too competitive for successful intercropping in high-biomass <i>sorghum</i> production systems.
%K High-Biomass <i>Sorghum</i>
%K Legumes
%K Green Manure
%K Intercrop
%K Cowpea
%K Crimson Clover
%K Soil Organic Carbon
%K Soil Nitrogen
%U http://www.scirp.org/journal/PaperInformation.aspx?PaperID=133924