Effects of farmyard manure and tillage systems on soil physical properties and corn yield in central Iran

Abstract

Tillage management and manure application are among the important factors affecting soil physical properties and crop yield. A 2-year field experiment was conducted on a silty clay loam soil (fine-loamy, mixed, thermic Typic Haplargids). Effects of two tillage systems (moldboard plowing as conventional tillage (T1) and disk harrowing as reduced tillage (T2)) at three farmyard manure rates (zero (M1), 30 (M2), 60 (M3) Mg ha-1) were studied on the soil physical properties and corn (Zea mays L.) yield. The experiment was carried out in split block design with three replications. Organic matter (OM) content, bulk density (BD), saturated hydraulic conductivity (Ks), aggregate mean weight diameter (MWD) and dry biomass yield (DBY) were measured after harvesting in the second year. Manure application increased OM on both the row and inter-row tracks significantly. Manure application rate of 60 Mg ha-1 increased MWD (0.33, 0.40 and 0.75 mm for M1, M2 and M3, respectively) at the 0-5 cm soil layer, but the effect was not significant below 5 cm depth. Adding manure significantly decreased soil BD on the row tracks (1.39, 1.22 and 1.17 Mg m-3 for M1, M2 and M3 treatments, respectively), but did not have any significant effect on the inter-row tracks. Hydraulic conductivity was improved by manure applications both on the row and inter-row positions. Manure treatments M2 and M3 increased DBY compared to the M1 treatment. Although moldboard plowing increased the depth of root penetration significantly (43 cm for T1 and 30 cm for T2), the effect of tillage systems on yield and soil physical properties was not significant. © 2002 Elsevier Science B.V. All rights reserved.