Interactive Effects of Tillage and Mulch Type on Soil and Crop Canopy Temperature and Yield of Sorghum (Sorghum bicolor, L)

Abstract

This paper investigates the interactive effects that tillage and mulch types have on soil and crop canopy temperature and the subsequent influence on final grain yields of a sorghum (Sorghum bicolor var rakodzi) crop stand. Two experimental sites, one farmer managed, and the other researcher managed were established in Mbire District of Mashonaland West Province in Zimbabwe during the 2020/2021 Zimbabwean farming season. A 3x4 factorial experiment laid in a Randomized Complete Block Design with three replications, was conducted to investigate the hypothesis that tillage and mulch have no effect on soil and crop canopy temperatures. Significant interactions (P<0.05) occurred between mulch and tillage types to influence canopy temperature at critical stages of late vegetative and grain filling at 25 and 75 days after sowing, respectively. Mulch and tillage types also interacted significantly (p<0.05) at critical stages of booting and grain filling at 50 and 75 days after sowing respectively to subsequently influence final grain yield. Sorghum straw used as mulch in raised beds resulted in the highest grain yields of 2.89 tons Ha^-1.  Conversely, lowest grain yields were realized from raised beds with no mulch as 1.89 tons Ha^-1. Thus, it was established that tillage and mulch can interact to affect both crop canopy and soil temperature at crop critical stages that will in turn impact on crop final grain yields. Farmers in the semi-arid regions of Zimbabwe are encouraged to be cognisant of this interactive effect to maximise sorghum crop productivity.