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221.
222.
A soil's responses to phosphorus (P) input differs based on its chemical composition. Soil acidity and the presence of metallic cations dictate a soil's chemical composition. Currently, soil P application recommendations are universal and do not account for differing soil composition. A targeted soil-specific approach is required to optimize P efficiency and availability. A pot incubation experiment was established to explore the effects of contrasting lime and P application rates across a range of soils (25), characterized by fine particle size and high levels of soil organic matter. Three contrasting rates of P were applied (0, 50, and 150 kg P ha−1) both with and without ground lime (CaCO3) at 5 tonne ha−1 over a 140-day incubation period. The addition of lime buffered the soil, increasing nutrient availability and reducing P fixation. The 50 kg P ha−1 treatment rate was required to achieve sufficient plant available P in both mineral soil textural classes. Current legislative recommendations however do not allow the application of such rates, which has an impact on agronomic performance. Loam soils experienced a greater increase in M3 soil P in comparison to clay and organic soils. Organic soils posed a major threat to water quality due to poor P retention. A re-evaluation of P recommendations is required to account for soil variability as current P allowances are insufficient on these particular soils. 相似文献
223.
A 2 × 2 × 2 factorial arrangement was used to investigate a 21 day study on the interaction between dietary crude protein (CP) (160 versus 200 g/kg), lactose level (50 versus 230 g/kg), and inulin supplementation (0 versus 15 g/kg) on piglet performance, diet digestibility, faecal volatile fatty acid (VFAs) concentration and selected microbial populations post weaning. Two hundred and fifty six weaned piglets (24 days old, 7.4 kg live weight, S.D. = 1.5 kg) were blocked on the basis of live weight and were assigned to one of 8 dietary treatments (n = 8) for 21 days. There was an interaction between CP and lactose concentration on average daily gain (ADG) during the overall experimental period. Pigs offered high CP diets containing 230 g/kg lactose increased ADG compared to those pigs offered high CP diets containing 50 g/kg lactose. However, there was no effect of lactose concentration in the low CP diets. There was a significant interaction (P < 0.05) between lactose level and inulin supplementation on Lactobacilli spp., Enterobacteria spp. and branched chain VFAs. Pigs offered inulin supplemented 230 g/kg lactose diets increased Lactobacilli spp. (P < 0.05) and decreased Enterobacteria spp. (P < 0.05) and branched chain VFAs (P < 0.05) compared to those offered the inulin supplemented 50 g/kg lactose diets. However there was no effect of lactose concentration in the non inulin supplemented diets. In conclusion, high CP diets and high inclusion levels of lactose improved piglet performance post weaning. Inulin supplementation had an additional effect in the 230 g/kg lactose diets through increased Lactobacilli spp. and decreased Enterobacteria spp. and branched chain VFAs. 相似文献