AN ECONOMIC STUDY OF THE IRRIGATION PERIODS’ EFFECTS ON SOME SOIL PROPERTIES AND FABA BEAN CROP PRODUCTIVITY

Abstract

This study aims to economically evaluate the water use efficiency at three rates of irrigation (1, 2, and 3) with the comparison between using 11.9 ton ha-1 application rate of the biochar and/or compost along with the mineral fertilization on the yield and quality of the faba bean crop. Two field experiments were conducted at El-Qantara Sharq farm Ismailia Governorate, Egypt, (winter seasons of 2020/2021 and 2021/2022) in a split-plot design with three replicates. The main factor F1 was the irrigation rates: rate 1 (3571.43 m3 ha-1), rate 2 (4761.90 m3 ha-1), and rate 3 (5952.38 m3 ha-1) while the sub-factor F2 was the type of the soil additive (biochar, compost or mineral). The soil-available N (mg kg-1) has increased relative to that before cultivation in the range 11.3 – 55.5% that was non-significant due to the irrigation rates (main factor F1) but a significant due to the soil additives (sub-factor F2). The studied irrigation rates as well as the soil additives have increased the soil-available concentration (mg kg-1) of K, Mn, and Zn significantly and the available P, and Fe but non-significantly at p < .05. The most significant relative increase compared to the soil-available content (mg kg-1) before cultivation was found for the compost at the irrigation rate 3 by 6.9% for K, 78.3% for Mn, and by 44.1% for Zn. The increase in the available nutrients followed the order irrigation rate 1 (3571.43 m3 ha-1) < rate 2 (4761.90 m3 ha-1) < rate 3 (5952.38 m3 ha-1) and the order mineral < biochar < compost. The increased yield (ton ha-1) of pods and seeds at the rate 3 relative to rate 1 was by 6.1% and 28.4% for the mineral fertilization, by 11.6% and 13.4% for the biochar, and by 15.0% and 26.1% for the compost, respectively. This increase was dependent on both factors F1 and F2 since their interaction was highly significant. At the irrigation rate 3, the total costs increased in the direction biochar (13095 LE) < compost (13333 LE) < mineral (14404 LE). The maximum net return was at the irrigation rate 2 for the compost (36837 LE) followed by the biochar (34010 LE) then at the rate 3 for the mineral fertilization (28326 LE). The return and net return with respect to the costs were also increased in the same order: rate 2 (compost) > rate 2 (biochar) > rate 3 (mineral). The application of the compost and/or the biochar is more efficient at the rate 2 than the single use of the mineral fertilization that need greater level of the irrigation water otherwise the yield decreases. The maximum water unit return has increased by 32.3% and 21.9% for the compost and biochar at rate 2, respectively, relative to the mineral at rate 1.