Cracking of a vertisol as influenced by puddling and residue management under rice-wheat cropping system

The present study characterizes the cracking behaviour of a Vertisol as influenced by puddling and residue management; estimates the crack development rates; establishes the functional relationship between crack parameters and soil physical properties and proposes puddling and residue management options in rice-wheat crop sequences in central India. The observations were recorded at harvest of rice (cv. IR 36) crop in the sequence, grown during the wet season under three puddling treatments viz., no puddling i.e. direct seeding (P₀), puddling by four passes of 5 hp power tiller (P₁) and puddling by eight passes of 5 hp power tiller (P₂) and two residue treatments (residue-retained; R_r and residue-removed; R₀). The length, width and depth of cracks increases significantly with increase in intensity of puddling as well as with time. Crack length and depth did not vary significantly with residue management, but crack width varied significantly. The surface area of cracks was higher under puddled soil than the unpuddled one. In the residue-retained plots, the surface area was lower than in the removed one. The crack development rate for length was 14.58, 10.13 and 9.85; for width 0.100, 0.156 and 0.157; and that for depth 0.588, 0.449 and 0.482 cm day⁻¹ in direct seeding, puddling by four passes and by eight passes power tiller, respectively. The rate for length, width and depth in residue-removed and residue-retained were 13.61 and 9.42; 0.128 and 0.112; and 0.596 and 0.414 cm day⁻¹, respectively. The effects of cracking in rice on yield of wheat showed that the yield of wheat under residual effect of P₂ and P₁ was significantly lower than the yield under P₀. It is suggested that for reduction of cracking after harvest of rice crop in Vertisol, the soil should be puddled less and also the residue of the previous crop should be retained.