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Diversification of current Oklahoma no-till cropping systems using cool season and warm season cover crops

Meeks, Kevin
This study evaluated fall and summer cover crop performance from a forage production, forage quality and water use efficiency standpoint. Five fall cover crop mixtures, for three site years, and six summer cover crop mixtures, for five site years, were evaluated for yield, total nitrogen, nitrogen uptake, acid digestible fiber, neutral digestible fiber, and relative feed value. The six summer cover crop mixtures were evaluated for their potential role to be planted in place of a summer fallow period in a continuous wheat system from a soil moisture and water use standpoint. The results indicated that rye containing fall cover crop mixtures had the highest yields, but lowest relative feed value. Some of the non-rye containing mixtures had higher feed values than the control, but had less yield potential. Summer cover crop mixtures containing all or a portion of legumes produced intermediate yields combined with the highest forage quality. No significant differences in wheat grain yield were seen between cover crop treatments and fallow treatments. However, the fallow plots produced, on average, 161 kg ha-1 more grain yield. Grain yield reduction was presumably caused by less soil moisture content at the time of planting. However, in-season and post-wheat harvest soil moisture values in the cover crop treatments were equal to or greater than soil moisture in the fallow treatment. Utilization of the summer cover crops, as a forage, should be done in-order to offset the seed cost due to the lack of cash crop yield improvements.