Study the Effect of Levels and Methods of Potassium Addition on the Behavior of Potassium under the Drip irrigation System and the Cultivation of Maize Crops

Abstract

A field experiment was carried out in the experimental field of the Department of Soil Sciences and Water Resources - College of Agriculture / University of Wasit on silty sand soil, in order to study the effect of potassium levels, methods and partition of its addition on the growth and yield of maize (Zea mays L.) var. Fajr 1. The experiment factors included three levels of potassium sulfate (0, 100 and 200 kg K ha-1), denoted by K0, K1, K2,and three meth¬ods of applications (conventional, spray, and capsule) and denoted by T, C, F, beside the po¬tassium fertilizer was divided into two batches B1, and B2.The experiment was carried out according to RCBD design with three replications.The results showed that the addition of potassium fertilizer significantly increased the soluble, exchange and non-exchange content of potassium in the vegetative growth and crop maturity stages, especially at the K2 level. The soluble potassium values reached the highest value for the treatment K2CB1 13.35×10-2 and 10.33×10-2 cmol. Kg-1, which did not differ significantly from K2FB1treatment during the two stages of growth respectively, and there was a decrease in the soil content of soluble potas¬sium as the plant growth stage progressed. Whereas for the exchangeable potassium, the treatment K2TB2 outperformed K2TB2 by giving its highest value, as it reached 84.19x10-2 and 68.38 x 10-2 cmol. kg-1 for the two stages of growth, respectively, and that was not signifi¬cantly different from the two methods of addition (C) and (F) in the first stage, while it sig¬nificantly outperformed them in the second stage. These rates decreased during the maturity stage of the crop compared to the vegetative growth stage. For the non-exchangeable potas¬sium during the first stage, the treatment K2FB1 gave the highest rate during the first stage, as it reached 87.52×10-2 cmol. Kg-1 and it did not differ significantly from the traditional addi¬tion method (T) and in one batch B1.As for the second stage, there are no significant differ-ences in the three methods of addition, and the traditional addition method (T) gave the high¬est values of 61.88x10-2 cmol.Kg-1 and at the method of addition (T) with one batch B1, and at the same level of potassium fertilizer K2. The results of the kinetics experiment showed that the total liberated amount of potassium, when the conventional addition to the soil and at the second level, with two doses, gave the highest values compared to other methods. The equa¬tions of first order, zero order, and force function give a good description of the potassium liberation process. However, the first-order equation exceeds the rest of the mathematical equations by registering the highest correlation value and the lowest value of the standard error rate.