Soil and nutrients losses under different crop covers in vertisols of Central India

Abstract

PURPOSE: Accelerated erosion removes fertile top soil along with nutrients through runoff and sediments, eventually affecting crop productivity and land degradation. However, scanty information is available on soil and nutrient losses under different crop covers in a vertisol of Central India. Thus, a field experiment was conducted for 4 years (2010–2013) to study the effect of different crop cover combinations on soil and nutrient losses through runoff in a vertisol. MATERIALS AND METHODS: Very limited information is available on runoff, soil, and nutrient losses under different vegetative covers in a rainfed vertisol. Thus, the hypothesis of the study was to evaluate if different crop cover combinations would have greater impact on reducing soil and nutrient losses compared to control plots in a vertisol. This experiment consisted of seven treatment combinations of crop covers namely soybean (Glycine max) (CC₁), maize (Zea mays) (CC₂), pigeon pea (Cajanus cajan) (CC₃), soybean (Glycine max) + maize (Zea mays) − 1:1 (CC₄), soybean (Glycine ma x)) + pigeon pea (Cajanus cajan) −2:1 (CC₅), maize (Zea mays) + pigeon pea (Cajanus cajan) − 1:1 (CC₆), and cultivated fallow (CC₇). The plot size was 10 × 5 m with 1% slope, and runoff and soil loss were measured using multi-slot devisor. All treatments were arranged in a randomized block design with three replications. RESULTS AND DISCUSSION: Results demonstrated that the runoff and soil loss were significantly (p < 0.05) higher (289 mm and 3.92 Mg ha⁻¹) under cultivated fallow than those in cropped plots. Among various crop covers, sole pigeon pea (CC₃) recorded significantly higher runoff and soil loss (257 mm and 3.16 Mg ha⁻¹) followed by that under sole maize (CC₂) (235 mm and 2.85 Mg ha⁻¹) and the intercrops were in the order of maize + pigeon pea (211 mm and 2.47 Mg ha⁻¹) followed by soybean + maize (202 mm and 2.38 Mg ha⁻¹), and soybean + pigeon pea (195 mm and 2.15 Mg ha⁻¹). The lowest runoff and soil loss were recorded under soybean sole crop (194 mm and 2.27 Mg ha⁻¹). The data on nutrient losses indicated that the highest losses of soil organic carbon (SOC) (25.83 kg ha⁻¹), total nitrogen (N), phosphorus (P), and potassium (K) (7.76, 0.96, 32.5 kg ha⁻¹) were recorded in cultivated fallow (CC₇) as compared to those from sole and intercrop treatments. However, sole soybean and its intercrops recorded the minimum losses of SOC and total N, P, and K, whereas the maximum losses of nutrients were recorded under pigeon pea (CC₃). The system productivity in terms of soybean grain equivalent yield (SGEY) was higher (p < 0.05) from maize + pigeon pea (3358 kg ha⁻¹) followed by that for soybean + pigeon pea (2191 kg ha⁻¹) as compared to sole soybean. Therefore, maize + pigeon pea (1:1) intercropping is the promising option in reducing runoff, soil-nutrient losses, and enhancing crop productivity in the hot sub-humid eco-region. CONCLUSIONS: Study results highlight the need for maintenance of suitable vegetative cover as of great significance to diffusing the erosive energy of heavy rains and also safe guarding the soil resource from degradation by water erosion in vertisols.