Effectiveness of conservation agriculture (tillage vs. vegetal soil cover) to reduce water erosion in maize cultivation (Zea mays L.): An experimental study in the sub-humid uplands of Guatemala

Abstract

Cultivated uplands in tropical latitudes are severely affected by soil water erosion. Conservation agriculture (CA) is specifically intended to control erosion. The aim of the present study is to analyse the effectiveness of CA measures to reduce the erosion in maize cultivation (Zea mays L.) on andosols in the mountains of southern Guatemala. Resolving this question is crucial to the development of sustainable soil policies appropriate to the conditions prevailing in this region. The study was conducted over a three-year period, from 2017 to 2019, on three experimental plots managed under conventional tillage (CT), reduced tillage (RT) and no-tillage (NT). The general-to-specific (GETS) method, based on reduction theory, was used to generate explanatory models of the erosion-affected surface. The study was carried out at two scales, first, with the complete database, and second, the database was segmented according to the agricultural management systems. The results showed different rates of eroded soil surface between the three management systems: 73.2% under CT, 41.3% under RT and 20.4% under NT. Analysis of the complete database (n = 36) showed that the litter cover (ryl.p = –0.86, p < 0.001) and the soil disturbance (ryp.l = 0.57, p < 0.001) were, in that order, the factors with the greatest explanatory power of the eroded surface. The segmented analysis (n = 12) showed that the management system adopted had a decisive influence on the ground cover (litter and weed cover) and, therefore, on the soil erosion. Under CT, the eroded surface was only correlated with the weed cover (ryw.l = –0.68, p < 0.05), under NT only with the litter cover (ryl.w = –0.89, p < 0.001) and under RT the erosion did not correlate with either of the vegetal layers. Three conclusions are derived from this study. First, litter layer was the key explanatory factor of erosion. Second, this factor is highly influenced by the agricultural management system. The proportion and distribution of the litter layer in each management situation were key to explaine the different soil erosion rates between the three management systems. And finally, it is proposed for the area of this study the soil management under NT with a dense and well distributed litter cover.