Soil structural improvements with the addition of Lantana camara biomass in rice-wheat cropping

Abstract. A long-term field experiment was initiated in June 1988 in a silty clay loam soil to investigate the potential of Lantana camara, an obnoxious weed, for improving structural properties and productivity of soil in rice-wheat cropping. Lantana was incorporated into the soil 10–15 days before puddling at 10, 20 and 30 t/ha (fresh weight). At the end of the sixth cropping season, Lantana additions increased the organic carbon (OC) of the 0–15 cm soil layer by 11–24%, and of water-stable aggregates (WSA, 0.50–8.0 mm diameter) by 10–21%; OC of WSA <0.50 mm diameter remained unaffected. About 17–25% of the applied OC was retained in the soil. The OC increase resulted in a decrease in bulk density of the plough layer (0–15 cm) by 7%, a decrease in aggregates of 2–8 mm diameter and of clods by 4% and 6%, respectively. There was an increase in water-stable aggregates and aggregate porosity, and a decrease in clod-breaking strength from 420 to 216 kPa. Soil cracking at the surface changed from wide, deep cracks in hexagonal pattern to a close-spaced network of fine cracks. Lantana additions increased <5mm wide cracks at the expense of 10–20 mm wide cracks; 5–10 mm wide cracks remained unchanged. Total volume of cracks decreased by 36% and surface area of cracks by 55% compared with the control plots.