Effects of subsoil amendments on soil physical properties, crop response, and soil water quality in a dry year

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Date: Mar. 2010
From: Australian Journal of Soil Research(Vol. 48, Issue 2)
Publisher: CSIRO Publishing
Document Type: Report
Length: 5,271 words

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Abstract :

In southern Australia the ability of field crops to extract soil moisture and nutrients from depth depends on the physical and chemical properties of the subsoil. In texture-contrast soils accumulation of water and nutrients in the E or A2 horizon, immediately above a clay B horizon of much lower hydraulic conductivity (herein called the interface), may generate lateral flows and enhanced nutrient and solute transfer to water bodies. Evidence that deep-ripping with addition of subsoil nutrients can increase crop productivity in regions having hostile, alkaline subsoils led to experiments to test whether this response was related to an increase in the use of water and nutrients in the subsoil. Our study measured the effects of deep-tipping with and without amendments on soil physical and chemical properties of the A and upper B horizons of 2 South Australian soils. Deep-ripping and deep-placement of nutrients increased grain harvest weight even in an exceptionally dry season. The greater yield was accompanied by significantly lower field-penetration resistance to 0.35 0.50 m depth, which we hypothesise enabled the crop to better access stored soil water and deep placed nutrients in the subsoil. Residual effects from deep-ripping were minimal after 4 growing seasons; therefore, ripping will need to be practiced at regular intervals to maintain treatment effects. The ripping and nutrient amendments had no significant effect on exchangeable sodium percentage, electrical conductivity, and readily extractable phosphorus and nitrate-nitrogen, despite changes in these soil properties between spring and harvest sampling. Additional keywords: compaction, water quality, nutrients, subsoil amelioration.

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Gale Document Number: GALE|A225247435