EFFECT OF DIFFERENT TYPES OF IRRIGATION SYSTEMS ON SOYBEAN PRODUCTION UNDER CLAYEY SOIL CONDITIONS

Abstract

Water is considered one of the most critical input resources for sustainable development at crop production. Selecting suitable irrigation system is very important to get high crop production and overcome water shortage. A field experiment was carried out at Rice Mechanization Center (RMC), Meet El-Deepa, and Kafer El-Sheikh Governorate during summer season 2014/2015 for soybean. The main aim of this research is to study the effect of different drip irrigation treatments on the productivity of soybean crop and irrigation water use efficiency (IWUE) under clayey soil conditions. The field treatments were designed as a split plots experimental design. The main plots were operating pressure head levels of 6(P1), 5(P2), 4(P3), and 3 meter (P4).Sub-main plots were included continuous drip irrigation (C), two levels of pulse drip irrigation in 15 min on/15 min off (S1) and 20 min on/20min off (S2) with three replication. Furrow irrigation (Tf) was used as control treatment soybean productivity, irrigation water use efficiency IWUE, uniformity parameters, and some plant characteristics were conducted to evaluate the performance of irrigation system and operating pressures. The important results indicated that:  Pulsed drip irrigation achieved a good water distribution in clayey soil.  Soybean productivity was increased by the percentage of 24.9, 23.7, 19.3, 14.0, 1.2% comparing with (Tf) for P1S1, P1S2, P1C, P2S1, P2S2, respectively. Wherever, it was decreased by the percentage of 2.8, 3.6, 21.1, 26.5, 37.5, 47.7 % comparing with Tf for P2C, P3S1, P3S2, P3C, P4S1, P4S2, P4C, respectively.  The results showed that the highest values of IWUE and distribution uniformity were 0.54 kg/m3 at P1S1 treatment and 96.61% at 6m pressure operating head (P1).-44- Application of pulsed drip irrigation was more effective to improve the front wetting zone of clay soil.  In conclusion, pulse drip irrigation treatment of (15 min open/15 min close) and operating pressure head of 6m gave the best results. 1. INTRODUCTION t is necessary to use modern techniques to promote productivity per unit area by using modern irrigation systems, which the important technologies that help to improve the productivity in addition to reducing the amount of water added to the crop. Study of engineering factors affecting on modern irrigation systems such as pulsed surface drip irrigation and its impact on the productivity of crop soybean and irrigation water use efficiency are the most important problems faced by the ongoing this search. Karmeli and Peri (1974) suggested that pulse irrigation is an irrigation technique achieving a relatively low application rate while using an irrigation device with a higher application rate. Complete pulse irrigation is composed of a series of irrigation time cycles where each cycle includes two phases: the operating phase followed by the resting or non-operative phase. Mostaghimi and Mitchell (1983) conducted laboratory experiments to study effects of trickle emitter discharge rate on the distribution of soil moisture in a silty-clay loam soil. The results indicated that on/off trickling wets a greater volume of soil with the same amount of applied water. Thus, reduction in the downward movement of soil moisture under pulsed applications would cause less deep drainage below the root zone. Pitts et al.(1991)found that the two drip irrigation frequencies (three times per day, one time per day) had not affected tomato yield. However, root length density was significantly affected by irrigation treatment at the 0 to 0.15 m depth with the more frequent irrigation treatment. Kang (2000) evaluated the effect of operating pressure heads on water application uniformity in micro irrigation sub main unit. Results showed that water application uniformity either increases or slightly decreases as operating pressure head increases in a range when the emission exponent x ≤ 0.5 in most cases. The water application uniformity decreases as operating pressure head increases in a range when the emission exponent x > 0.5.