Soil acidification as influenced by crop rotations, stubble management, and application of nitrogenous fertiliser, Tarlee, South Australia

Abstract

Soil acidification, as influenced by N fertiliser, stubble management, and crop rotations, was investigated using soil samples from a long-term rotation trial at Tarlee, South Australia. With the effects of combination of treatment inputs (wheat–lupin, stubble retention and N-fertiliser application), the pHCa (0–10 cm depth) declined from the starting value of 6.12 to 4.50 after a 14-year period. All of the treatments caused the soil pH to decrease. The mean acidification rates for the period 1978–1992 varied from 0.5 to 2.22 kmol H+/ha.year for different treatments. Although the rainfall at Tarlee (483 mm) is not sufficient to cause regular drainage events, it is likely that downward movement of NO3– in the soil profile has caused acidification in the surface soil. Also the retention of stubble caused more acidification than where there was regular stubble burning or removal. The acidification resulted in an increase in soil exchangeable Al and Mn and extractable Al and Mn, and the decrease in soil exchangeable base cations. The values for soluble Al (extracted in CaCl2) in 1992 were 1.58 and 2.45 mg/kg (0–10 cm depth) for the wheat–bean and wheat–lupin rotations, but the percentage of Al in the ECEC was low. It is not known whether this acidity has any impact on yields of field crops at this stage. But with soluble Al and the percentage of Al in ECEC increasing, it is possible that Al toxicity may occur in the high input-output cropping soils in South Australia. acidity, pH, aluminium, manganese.

Dynamics of soil nitrogen availability indices in a sandy clay loam soil amended with animal manures

“…-N and NO 3 --N contents of the soils applied with NPK fertilizer at 14 WAI compared with cattle, goat and manure treated soils rates could be attributed to acidic properties of NPK fertilizer. This corroborated the study results of Xu et al (2002) that acidity reduces soil microbial activity resulting in reduced nutrient mineralization. This could also be attributed to depletion of soil organic matter as a result of synthetic fertilization (Jonathan 2006).…”

“…-N between 18 and 22 WAI could be attributed to ammonia volatilization (Meissinger and Jokela 2000) while low NO 3 --N contents between 18 and 22 WAI could be attributed to leaching (Tom 2002;Marco et al 2002) and plant root uptake. The low NO 3 --N contents in soil applied with NPK fertilizer at 18 WAI compared with 8 and 14 WAI could be attributed to acidic properties of NPK fertilizer, since acidity reduces soil microbial activity and this would in turn reduce nutrient mineralization (Xu et al 2002).…”

Determination of critical pH and Al concentration of acidic Ultisols for wheat and canola crops

“…At present, acid deposition is still a serious factor that accelerates soil acidification in China (Vogt et al, 2006;Zhao et al, 2009). Soil acidification can also be accelerated by applying excessive NH + 4 -or R-NH 2 -based fertilizers (Bolan et al, 1991;Malhi et al, 1998;Xu et al, 2002;Schroder et al, 2011). Under the intensive land use in China, the sharp increase in application of N fertilizer in crop systems has greatly accelerated soil acidification in the last three decades (Guo et al, 2010).…”

Effects of Land Use and Management on SoilHydraulic Properties

“…Soil formation is a slow process, while soil physical, chemical and biological degradation processes, such as soil compaction [5], erosion [6], acidification [7,8], decline in organic matter content [9], etc., can occur relatively fast, especially in areas of agricultural land use [10,11]. The faster pedogenic processes reach steady state after tens to hundreds of years, while slow processes of soil formation evolve on a time scale of thousands to tens of thousands of years [12].…”