Cropping systems and Agronomic Management Research for Peanut

Two new projects were initiated in the 2016 project involving a more in-depth analysis of the effect of Ca on nutrient availability and uptake by the plant in comparison with other needed cation nutrients such as Mg and K. The Ca:K ratio needs to be considered when determining Ca recommendations, but more work needs to be done to evaluate Ca:K+Mg, and whether any of these nutrients might affect availability and uptake of the others. In one experiment, Ca was applied as either lime, gypsum, or both in irrigated and non-irrigated conditions. There was no effect on yield as a result of Ca application, although there was a much greater increase in soil Ca concentration where lime was applied (including lime+gypsum) compared to gypsum alone or no Ca added. Also, the change in Ca concentration was larger in the non-irrigated plots than irrigated because the additional water helped move Ca into the pods and likely also leached some Ca below the pegging zone. In the other experiment, treatments of Ca and Mg either alone or in combination were made to peanut. The change in soil concentration increased for Ca, but actually caused a decrease in Mg whenever gypsum was applied. Flooding the soil with Ca caused Mg to be less available, even when MgSO4 was applied with the gypsum. But the soil test levels for these nutrients were considered adequate in both trials even without application of supplemental nutrients, so there was very little effect on yield among the treatments. The only yield increase was observed with a maximum treatment of gypsum plus a 2x rate of MgSO4, which had greater yield than the control.