Uganda Journal of Agricultural Sciences

Log in or Register to get access to full text downloads.

Remember me or Register

Amelioration of sandy soils in drought stricken areas through use of Ca-bentonite

O Semalulu, M Magunda, D.N. Mubiru


Soil moisture shortage is a major limiting factor to agricultural production in eastern Africa, in view of increased drought incidences and seasonal rainfall variability. This study evaluated the potential for Ca-bentonite (a 2:1 clay mineral) as a possible amendment for increased moisture retention by sandy soils in drought stricken/prone areas in Uganda. The study was conducted both in the greenhouse at NARL-Kawanda and in the field, Nakasongola district. In the greenhouse (27-30oC), Ca-bentonite was mixed with a sandy soil in proportions of 0, 5, 10, 15 and 20% by weight, replicated three times. The mixtures were watered to field capacity (30% water) then maize (Longe V) planted and left to grow for 5 weeks without any additional water application. Under field conditions, Ca-bentonite was applied on sandy soils in the drought-prone Lwabiyata sub county, Nakasongola district in central Uganda. Treatments included: Ca-bentonite applied 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 a randomised block design with three replicates. Under greenhouse conditions, Ca-bentonite application significantly (P<0.05) increased the soil moisture retention, pH, N, P, Ca and Mg content, and subsequently, maize dry matter yield. Averaged over 2 seasons, field application of 2.5 t Ca-bentonite ha-1 increased maize grain yield by 37.6%. Yields were significantly (P<0.05) higher (79.8 to 82.0% above the control) where bentonite (2.5 t ha-1) was combined with DAP (62.5 kgha-1 or FYM (2.5 tha-1). The results suggest that Cabentonite has potential as a soil amendment for moisture conservation, neutralising acidity, and improving N, P, Ca and Mg content in sandy soils, and consequently support crop growth and yield. Thus calcium bentonite presents a possible amelioration for sandy soils of low fertility in drought stressed environments. It is thus a promising technology for climate change adaptation in drought prone areas.

Keywords: Climate change adaptation, drought mitigation, moisture stress, soil moisture conservation, soil fertility management
AJOL African Journals Online