Effects of Conservation Tillage on Soil Moisture, Chemical Properties, Maize and Bean Physiological Parameters and Yields in Embu County Kenya
Kyalo, Munyao Joseph
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Production of Zea mays L. and Phaseolus vulgaris L. has been lagging at 1.8 and 0.5 t/ha respectively. Yield potentials are 6.0 and 2.5 t/ha for maize and bean respectively. This is attributed to frequent dry spells and low soil fertility. Sustainable agricultural approaches such as conservation tillage (CT) have been embraced by farmers and have contributed to improvement in chemical and physical properties of soil and crop yields. However, the physiological basis of the observed yield increase due to CT practices has not yet been reported hence the study. Objectives of the study were: to assess CT practices effects on soil moisture, soil chemical properties, maize and bean physiological parameters and yields. The study was carried out in two seasons at the Kenya Agricultural and Livestock Research Organization farm in Embu County. Experimental design was a split-plot arranged in a randomized complete block design with nine treatments replicated three times. Conservation tillage practices comprised Zero tillage (ZT) and Furrows/ridges (F/R) evaluated against conventional tillage (CVT). The test crops were maize and beans grown as intercrops or monocrops. Key data sets were: soil moisture, soil chemical properties, maize and bean physiological parameters and yields. Soil moisture was measured in each plot twice per month by the use of a PR2 moisture probe. Laboratory analysis of soil samples for organic carbon followed the Walkley and Black method, whilst Nitrogen analysis followed the Kjeldahl method. Analysis of Variance (ANOVA) was used to analyze all data sets with the Statistical Analysis System computer software (SAS). Treatment means differences were compared using Fisher’s least significant difference test. The CT (ZT and F/R) practices led to increase in soil moisture content, soil organic carbon, and soil nitrogen and soil pH that was significant (p ≤ 0.05). Significantly (p ≤ 0.05) higher nodules, chlorophyll concentration, sugars and starch were obtained for the beans under CT plots compared to those under CVT. The beans grown under F/R plots had grain yields of 1.3 t/ha in SR 2015 and 1.4 t/ha in LR 2016 in comparison to those grown under CVT plots which had grain yields of 1.2 t/ha in SR 2015 and 1.3 t/ha in LR 2016. Maize under CT plots had significantly (p ≤ 0.05) higher leaf area index, chlorophyll concentration, sugars and starch compared to those grown under CVT plots. Maize grain yield under ZT plots was 1.8 t/ha in SR 2015 and 2.2 t/ha in LR 2016 and that under F/R plots was 1.7 t/ha in SR 2015 and 2.1 t/ha in LR 2016 Maize grain yield under CVT plots was 1.8 t/ha in SR 2015 and 2.3 t/ha in LR 2016. It can be concluded that CT is a suitable technique for conserving soil water for plant use, improving soil health and crop physiological parameters hence the increased crop productivity. This study recommends the adoption of CT practices to enhance production of crops and ensure security of food for the studied area and other regions with comparable agro ecological conditions.