Short- and Long-Term Effects of Lime and Gypsum Applications on Acid Soils in a Water-Limited Environment: 1. Grain Yield Response and Nutrient Concentration

Abstract

Surface (0–10 cm) and subsoil (soil layers below 10 cm) acidity and resulting aluminum (Al) toxicity reduce crop grain yields. In South Western Australia (SWA), these constraints affect 14.2 million hectares or 53% of the agricultural area. Both lime (L, CaCO3) and gypsum (G, CaSO4) application can decrease the toxic effect of Al, leading to an increase in crop grain yields. Within the region, it is unclear if G alone or the combined use of L and G has a role in alleviating soil acidity in SWA, due to low sulfate S (SO4–S) sorption properties of the soil. We present results from three experiments located in the eastern wheatbelt of SWA, which examined the short-term (ST, 2 growing seasons), medium-term (MT, 3 growing seasons), and long-term (LT, 7 growing seasons over 10 years) effects of L and G on grain yield and plant nutrient concentrations. Despite the rapid leaching of SO4–S and no self-liming impact, it was profitable to apply G, due to the significant ST grain yield responses. The grain yield response to G developed even following relatively dry years, but declined over time due to SO4–S leaching. At the LT experimental site had received no previous L application, whereas, at the ST and MT sites, L had been applied by the grower over the previous 5–10 years. For the LT site, the most profitable treatment for wheat (Triticum aestivum L.) grain yield, was the combined application of 4 t L ha−1 with 2 t G ha−1. At this site, the 0–10 cm soil pHCaCl2 was 4.6, and AlCaCl2 was greater than 2.5 mg kg−1 in the 10–30 cm soil layer. In contrast, at the ST and MT sites, the pHCaCl2 of 0–10 cm soil layer was ≥5.5; it was only profitable to apply G to the MT site where the soil compaction constraint had been removed by deep ripping. The use of L increases soil pHCaCl2, resulting in the improved availability of anions, phosphorus (P) in the LT and molybdenum (Mo) at all sampling times, but reduced availability of cations zinc (Zn) in the LT and manganese (Mn) at all sampling. The application of G reduced Mo concentrations, due to the high SO4–S content of the soil.

Short- and Long-Term Effects of Lime and Gypsum Applications on Acid Soils in a Water-Limited Environment: 2. Soil Chemical Properties

“…While Bonnie Rock and Burracoppin are in the same rainfall zone, rainfall amount and distribution can differ, for example, annual rainfall at Bonnie Rock was 296 mm compared Burracoppin of 400 mm in 2015 [3]. Crop grain yield and nutrient concentration and measured soil chemical properties from the control treatment are presented by [3]. In summary, G application was profitable at the MT experiment where deep ripping had removed the subsoil compaction constraint.…”

“…Long term (1980-2018) average rainfall for the Bonnie Rock and Burracoppin sites are 309 mm (range 158-453 mm) and 364 mm (range 315-414 mm) respectively. While Bonnie Rock and Burracoppin are in the same rainfall zone, rainfall amount and distribution can differ, for example, annual rainfall at Bonnie Rock was 296 mm compared Burracoppin of 400 mm in 2015 [3]. Crop grain yield and nutrient concentration and measured soil chemical properties from the control treatment are presented by [3].…”

“…The distance of the experiment site for L sources was 370-380 km compared for the G source of 140-200 km. The L source consisted of 80-93% CaCO 3 while the G source contained 175-178 g S kg −1 and 214-224 g Ca kg −1 [3].…”

“…When the subsoil or soil layers below 10 cm contain an Al CaCl 2 content greater than 2.5 mg Al kg −1 , there is a significant reduction in wheat (Triticum aestivum L.) grain yield. Lime (L, CaCO 3 ) applied to Al toxic soils increases soil pH CaCl 2 and decreases soil Al CaCl 2 resulting in increased crop grain yields [2,3]. However, due to its comparatively low solubility, L broadcast onto the soil surface can be ineffective at treating subsoil Al toxicity in the short-term and medium-term [2].…”

“…In the first paper of this series, we concluded that the application of G is profitable in the low-rainfall, eastern wheat belt region of Western Australia despite the soils having a low capacity to adsorb SO 4 -S which results in rapid leaching of SO 4 -S and no self-liming effect [3]. In this paper, we examine the impact of surface application of G and L on soil chemical properties overtime to explain these crop grain yield responses.…”