Subsoiling and surface tillage effects on soil physical properties and forage oat stand and yield

• Published in: Soil & tillage research Vol. 40; no. 3; pp. 125 - 144
• Main Authors: Sojka, R.E., Horne, D.J., Ross, C.W., Baker, C.J.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 1997
• Subjects: AVENA SATIVA; Bulk density; Cone index; Conservation tillage; CROP YIELD; FACON SUPERFICIELLE; LABOR SUPERFICIAL; LABRANZA DEL SUBSUELO; NEW ZEALAND; No-till; NOUVELLE ZELANDE; NUEVA ZELANDIA; ODR; Paraplow; PROPIEDADES FISICO-QUIMICAS SUELO; PROPRIETE PHYSICOCHIMIQUE DU SOL; RENDEMENT DES CULTURES; RENDIMIENTO DE CULTIVOS; Soil aeration; SOIL CHEMICOPHYSICAL PROPERTIES; SOUS SOLAGE; SUBSOILING; SURFACE CULTIVATION; Bulk density; No-till; Cone index; Conservation tillage; Paraplow; ODR; Soil aeration
• ISSN: 0167-1987; 1879-3444
• DOI: 10.1016/S0167-1987(96)01075-6

Much of New Zealand's agriculture integrates animal and crop production on poorly drained, easily compacted soils. We hypothesized that soil properties affecting forage oat (
Avena sativa, cv Awapuni) establishment on land compacted by 15 years of conventional cropping might be influenced by various subsoiling and surface tillage combinations. Plots on a Moutoa silty clay (Typic Haplaquoll) were paraplowed (P), deep subsoiled (V), shallow subsoiled (S), or were left as non-subsoiled controls (C). Subsequently, the surface 15 cm was surface-tilled (T) using a power rotary-tiller and firmed with a Cambridge roller or were not tilled (N). Oats were then sown with a cross-slot drill. Subsoiling greatly reduced soil strength. Cone indices showed disruption to 40 cm with P, 36 cm for V, and 30 cm for S. Approximately 60% of profile cone indices to a depth of 0.5 m from subsoiled treatments were less than 1.5 MPa, compared to approximately 30% for C. T slightly improved strength distribution in non-subsoiled controls but had little effect in subsoiled treatments. Subsoiling without T continued to show improved profile cone index cumulative frequency 233 days after subsoiling. Subsoiling after T in this high rainfall climate eliminated most of the separation in cumulative frequency of soil profile cone index values by two weeks after T. T reduced emergence from 142 to 113 plants per square meter and reduced yield from 5318 to 3679 kg ha
−1. Forage yield increased from 3974 to 4674 kg ha
−1 with subsoiling. Soil porosity, saturated and slightly unsaturated hydraulic conductivities (
K
SAT and
K
−40) and air permeability were highly variable but generally increased with subsoiling. Oxygen diffusion rate (ODR) (using Pt microelectrodes) was also variable, but N and C treatments had consistently lower ODRs than T or subsoiled treatments. Generally, subsoiling without T produced better soil conditions and oat crop performance than the prevailing New Zealand practice of T without subsoiling.