Interactive effects of in situ rainwater harvesting techniques and fertilizer sources on mitigation of soil moisture stress for sorghum (Sorghum bicolor (L.) Moench) in dryland areas of Tanzania

Abstract

Nutrient deficiency, high rate of evapotranspiration, and insufficient and erratic rainfall are the critical challenges for crop production in the dryland areas (DLAs) of Sub-Saharan Africa, including Tanzania, where 61% of arable land is prone to drought. In addressing these challenges, field trials were conducted in central Tanzania to evaluate the interactive effects of ripping and tie-ridges with organic (FYM) and inorganic fertilizers (N) on the mitigation of the critical period of soil moisture stress (CPSMS) for sorghum yield performance. Both in situ rainwater harvesting techniques (IRWHT) and flat-cultivated land were integrated with 8 Mg FYM ha-1 , 70 Kg N ha-1 , and a combination of 35 Kg N ha-1 and 4 Mg FYM ha-1 (N+ FYM). Among the IRWHT, tie-ridges stored a significant water volume of 577 and 457 m 3 ha-1 , which mitigated the CPSMS by the maximum of 95% and 37% for the above-average rainfall and below-average rainfall season, respectively. However, it only registered the highest grain yield (2.02 Mg ha-1) and biomass (3.46 Mg ha-1) in a belowaverage rainfall season. The highest overall grain yield (5.73 Mg ha-) and biomass (12.09 Mg ha-1) were harvested in ripping with combined fertilizer treatments in an above-average rainfall season, while the lowest grain yield (0.5 Mg ha-1) and biomass (1.2 Mg ha-1) were registered in the flat-cultivation control in the belowaverage rainfall season. In the latter season, IRWHT increased the mitigation potential in the order; flat cultivation < ripping < tie-ridges; and sorghum yield, highly correlated with drought mitigation index. The results showed that sorghum grain yield and final biomass performance depend on the influence of IRWHT applied, rainfall amount, soil moisture level, integrated fertilizer, and length of the CPSMS. In the aboveaverage rainfall seasons, fertilizers mask the influence of the IRWHT. The opposite is true in the below-average rainfall season. Although ripping-N+ FYM resulted in the highest overall yield, the study recommends practicing tie-ridges integrated with N+ FYM due to regular occurrences of low and unreliable rainfall in the dryland areas.

Field edge rainwater harvesting and inorganic fertilizers for improved sorghum (Sorghum bicolor L.) yields in semi-arid farming regions of Marange, Zimbabwe

“…Studies by Mishra and Patil (2015), Shamme et al (2016), andSharma andBali (2017) showed a significant positive association between nitrogen and soil moisture on sorghum grain yield. Mahinda et al (2018) also found that the integration of the RWH method and nitrogen application improves crop productivity. The low grain yield response to nitrogen addition in the SC was due to low moisture content evidenced by the low gravimetric water content (Table 2).…”

“…Results support work by Nyamadzawo et al (2012 andNyamadzawo et al (2013) who reported water losses up to 50% being lost as runoff from croplands and disposed of through contour channels. The availability of assimilates, which is influenced by soil water availability, is critical for effective grain filling (Mahinda et al, 2018;Mupangwa et al, 2018). Thus, rainwater harvesting structures can sustain crop production during dry spells improving water use efficiency under rain-fed crop production systems in semiarid regions.…”

“…This was shown by higher water content being attained by tied contours and infiltration pits while the SC had the least water content (Table 2). Mahinda et al (2018) and Mupangwa et al (2016) reported that the RWH techniques have the potential to mitigate crucial water deficit periods through moisture retention in the rhizosphere.…”

“…Moisture stress is a common phenomenon that leads to low, unreliable grain output (Mupangwa et al, 2012). This makes crop production in dry-land locations is highly risky due to the high value of potential evapotranspiration, and lack of nutrients (Chianu et al, 2012;Mahinda et al, 2018). The low rainfall received in the semi-arid rain-fed farming areas reduces the rate of nutrient uptake efficiency affecting nutrient demand at critical crop growth stages (Mahinda et al, 2018).…”

“…This makes crop production in dry-land locations is highly risky due to the high value of potential evapotranspiration, and lack of nutrients (Chianu et al, 2012;Mahinda et al, 2018). The low rainfall received in the semi-arid rain-fed farming areas reduces the rate of nutrient uptake efficiency affecting nutrient demand at critical crop growth stages (Mahinda et al, 2018). If the entire spectrum of advantages from soil nutrient additions is to be achieved, cultural adaptive sustainable crop intensification strategies that preserve and increase the time of moisture availability to the plants are required to enhance sorghum productivity in low rainfall environments (Mundia et al, 2019).…”