Abstract
Beneficial management practices can be used to improve the crop productivity of tropical Alfisols. This study evaluated beneficial management practices to overcome the soil physical and chemical limitations for growing maize ( Zea mays ). The experiment was conducted in the Low Country Dry Zone (DL1b) on Reddish Brown Earth soil (Typic Rhodustalf). Four treatments; un-amended control (C), site specific fertilizer (SSF), biochar applied at 1 t/ha with SFF (BC+SSF) and rock powder applied at 10 t/ha with SSF (RP+SSF) were tested using maize as the test crop initially in the greenhouse and later in the field at DL1b for two growing seasons (2013 Yala and 2013/2014 Maha ) for their effects on crop growth and soil fertility. Soil was neutral, non-saline, sandy clay loam in texture with comparatively high clay content (27%) and low in organic matter content (1.5%) and deficient in N, P, S, Ca, Zn, and Cu, initially. In the greenhouse, plant dry weight increased significantly with the addition of amendments i.e., fertilizers alone (SSF), or BC+SSF or RP+SSF. In the field study, no significant differences were observed for soil pH with the addition of amendments but biochar application significantly increased cation exchange capacity, organic matter, potentially mineralizable nitrogen and carbon management index. Rock powder+SSF and BC+SSF significantly increased the grain yield over the control in both seasons. Both labile and recalcitrant C were significantly higher in BC+SSF treatment than the others. Further, application of BC and RP had no significant impact on soil textural fractions and bulk density, yet in both seasons, BC+SSF application increased the aggregate stability greater than other treatments. The results of the field experiment suggest that biochar and rock powder with adequate nutrients effectively improved soil fertility and productivity.
Highlights
Sri Lankan soils are generally low in soil fertility and high inputs are needed for crop production. Oldeman (1994) indicates that world’s agricultural lands are degraded as a result of atmospheric and water pollution, extensive cultivation, over-grazing, and land clearing like activities leading to salinization, soil erosion, and desertification
Nutrient imbalances, poor nutrient retention as a result of low organic matter content and poor drainage facilitated by high clay content were predicted as the site specific soil fertility constraints
The effects of a balance site specific fertilizer mixture, biochar and rock powder were tested for their effectiveness to rectify the problems
Summary
Sri Lankan soils are generally low in soil fertility and high inputs are needed for crop production. Oldeman (1994) indicates that world’s agricultural lands are degraded as a result of atmospheric and water pollution, extensive cultivation, over-grazing, and land clearing like activities leading to salinization, soil erosion, and desertification. Sri Lankan soils are generally low in soil fertility and high inputs are needed for crop production. The effects of management practices on soil fertility has been studied by evaluating the changes in soil. The use of mineral fertilizers in a balanced manner to supply nutrients and application of organic amendments for enriching soil organic carbon are two practices that could improve soil fertility. Problems linked to soil physical properties such as excessive or poor drainage, high erodability and compaction cannot be solved yet severely affect yield (Adeoye and Mohamed-Saleem, 1990; Akinci et al, 2004). Organic matter application is known to improve soil tillth even in compacted layers (Ekwue and Stone, 1995). Application of rock powder or sand to soil is not new because rock powder has been used as a soil amendment to tackle various soil constraints previously (Silva et al, 2013; Gillman et al, 2002)
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