Fig. 2

Analysis of variance of pH, SOC and TN (g kg⁻¹), AN, NH₄⁺-N, NO₃⁻-N, AP and AK (mg kg⁻¹). SOC: Soil organic carbon; TN: Total nitrogen; AN: Available nitrogen; NO₃⁻-N: Nitrite-N; NH₄⁺-N: Ammonium-N; AP: Available phosphorus; AK: Available potassium. S1: straw with nitrogen, S0: no straw with nitrogen, N0: no nitrogen, N1: 120 kg N ha⁻¹, N2: 180 kg N ha⁻¹.M, and N represent the maize straw mulch and nitrogen levels, respectively. ^*, and ^** indicate significance at the 5% and 1% probability level, respectively.