Effects of Irrigation and Fertilization on Some Upland Crops in Paddy Field of Thailand

Abstract

To determine the optimum amount of water required and irrigation interval with special attention to an effect of fertilizer application, furrow irrigation experiments on maize and on soybean were carried out in a paddy field of the Central Plain in Thialand during the dry season in 1974. Two different irrigation intervals; 4 day and 7 day, three different irrigation levels; 4 mm/day, 7 mm/day and l0 mm/day, and two different fertilization levels; the standard and heavy fertilization, respectively, were combined to set up 12 treatments (Table 1). Effects of irrigation and fertilization for the grain yield were nearly adverse between maige and soybean. Result of each experiment was summarized as follows: 1. Maize received irrigation water at the rate of 4 mm/day, being nearly equal to amount of the pan evaporation, attained better yield than that received the water at the rate of 7 mm/day and l0 mm/day. Four day irrigation interval seemed to introduce better yield as compared with 7 day one (Table 1 and Fig. 2). The dry matter production and the grain yield of maize in the hcavily fertilized plot (100 kg/ha of nitrogen) increased significantly as compared with those in the plot received the standard fertilizer (50 kg/ha of nitrogen). It may be concluded that the frequent light irrigation applied to the heavy fertilization p1ot achieved better yield than the heavy irrigation with the longer interval applied to the standard fertilization one.2. The dry matter production and the grain yield of soybean in the plot received irrigation water with 4 day interval were high as compared with those in the plot with 7 day one. The decreasing trend of the grain yield was seen only in the case of the heavy fertilization (40 kg/ha of nitrogen) being adversely related to an increase of irrigation water (Table 1 and Fig. 3). An increase of the nitrogen fertilizer application resulted in an adverse effect on the total dry weight and the grain yield. It may be concluded that the frequent light irrigation applying the standard fertilization (20 kg/ha of nitrogen) achieved better yield than the heavy irrigation with the longer interval applying the heavy fertilization.