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This article in SSSAJ

  1. Vol. 61 No. 1, p. 152-159
     
    Received: Mar 21, 1996
    Published: Jan, 1997


    * Corresponding author(s): f-hons@tamu.edu
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doi:10.2136/sssaj1997.03615995006100010023x

Long-Term Effects of Tillage and Fertilization on Soil Organic Matter Dynamics

  1. J. R. Salinas-Garcia,
  2. F. M. Hons  and
  3. J. E. Matocha
  1. Dep. of Soil and Crop Sciences, Texas A&M Univ., College Station, TX 77843-2474
    Texas A&M Univ. Agric. Res. and Extension Center, Corpus Christi, TX 78410

Abstract

Abstract

Understanding the effects of long-term management practices on soil C and N pools and activities is essential for sustaining soil productivity. The objectives of this study were to evaluate long-term and seasonal changes in soil organic C (SOC), soil microbial biomass C (SMBC) and N (SMBN), and mineralizable C and N in continuous corn (Zea mays L.) under conventional tillage (CT), moldboard (MB), chisel (CH), minimum tillage (MT), and no-tillage (NT) with low (45 kg N, 10 P kg ha−1) and high (90 N kg, 10 P kg ha−1) N fertilization. An Orelia sandy clay loam (fine-loamy, mixed, hyperthermic Typic Ochraqualf) in south Texas was sampled before corn planting in February, during pollination in May, and following corn harvest in July. No-tillage and MT retained more corn residue C input as SOC and SMBC than the more intensive tillage systems. Soil organic C, SMBC, SMBN, and mineralizable C and N were greatest in the surface 0 to 50 mm with NT and MT. Seasonal distributions of SMBC and mineralizable C were consistently greater in reduced-tillage systems (NT and MT), averaging 22 and 34% greater than plowed treatments at planting, 45 and 53% larger at pollination, and 36 and 34% higher at harvest, respectively, at a depth of 200 mm. The greater amount of crop residues remaining with MT and NT may have provided available substrate for maintenance of the larger SMB pool and the higher C and N mineralization in the 0- to 200-mm depth during the growing season. Higher N fertilization increased seasonal mineralizable C and N, but did not consistently affect SOC and SMB. Reduced tillage systems that promote surface residue accumulation provide an opportunity for increasing sequestration of C and mineralizable nutrients within SMB.

Contribution of Texas Agric. Exp. Stn.

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