Use of Ca-bentonite to ameliorate moisture and nutrient limitations of sandy soils in drought stricken areas

Abstract

Moisture shortage is a major factor limiting crop production in sandy soils. This study evaluated the potential for Ca-bentonite (2:1 clay mineral) as an amendment for increased moisture retention by sandy soils in drought stricken/prone areas. In the green house, maize was grown to sandy soil containing 0, 5, 10, 15 and 20% Ca-bentoniteby weight, replicated three times. The mixtures were watered to field capacity (30% water) then maize (Longe V) grown for 5 weeks without additional water. In the field, Ca-bentonite was applied on sandy soils in the drought-prone Lwabiyata sub- county, Nakasongola district, Central Uganda. Treatments included: Ca-bentonite at 0, 1.25 and 2.5 t ha^-1; DAP at 0, 62.5 and 125 kg ha^-1; urea at 0 and 60 kg ha^-1; and farmyard manure (FYM) at 0, 1.25 and 2.5 t ha^-1, arranged in arandomized block design with three replicates. Under greenhouse conditions, Ca-bentonite significantly (P<0.05) increased soil moisture retention, pH, N, P, Ca and Mg content, and subsequently, maize dry matter yield. Under field conditions, Ca- bentonitesignificantly (P<0.05) increased maize grain yield by 40%. Yields were even higher (65 to 108% above the control) where bentonite was combined with FYM and/or DAP. Results suggest that Ca-bentonite has potential asa soil amendmentfor moisture conservation, neutralizing acidity, and improving N, P, Ca and Mg contentin sandy soils, and consequently support crop growth and yield, and therefore presents a possible option for amelioration of sandy soils in drought stressed environments, hence climate change adaptation.