Dryland wheat yield dependence on rainfall, applied N and mulching in preceding maize

Abstract

To evaluate the response of dryland wheat (Triticum aestivum L.) to mulching in preceding maize and fertilizer N application field experiments were conducted for six years (1980–86) with maize-wheat sequence on a sandy loam soil in northern India. Four rates of N application viz. 0, 40, 60 and 80 kg N ha⁻¹ in wheat were combined with three mulch treatments viz. no mulch (M₀), paddy straw mulch (M_p) and basooti (Premma mucronate) mulch (M_b) applied at the rate of 4 tons ha⁻¹ on dry weight basis applied three weeks before harvest of maize. Mulching (M_p and M_b) increased (profile) stored moisture at wheat seedling by 31 to 88 mm. M_b also increased NO₃-N content by 33 to 42 kg ha⁻¹ in 0–120 cm profile over M₀ and M_p. Over the years, M_p increased wheat yield by 11 to 515 kg ha⁻¹ and M_b by 761 to 879 kg ha⁻¹. Wheat yield response to mulching was related to rainfall pattern during its growth season. Significant response to mulching was obtained only in years when rainfall during vegetative phase of the crop was low. Amount and distribution of rainfall during two main phases of crop development affected the N use efficiency by wheat. On an average, each cm of rain substituted for 3.5, 4.6 and 6.5 kg of applied N ha⁻¹ under M₀, M_p and M_b, respectively. Split rainfall for two main phases of crop growth, available stored water at seeding, fertilizer N and profile NO₃-N content accounted for 89 per cent variability in wheat yield across years and mulching treatments.