The fate of pig slurry phosphorus applied to a sandy loam soil under no-till cropping in southern Brazil

Repeated phosphorus (P) inputs can lead to the accumulation of surplus P in soil with enhanced potential risk of transfer and accelerated eutrophication of aquatic environments. Intensive pork production in Rio Grande do Sul in southern Brazil results in the generation of large quantities of P-rich waste in the form of pig slurry, which is used to fertilise crops. The aim of this study was to assess and quantify the impact of repeated application of pig slurry P over 8 years (2000–2007) on the fate of P in a sandy loam soil maintained under a mixed cropping regime. In a replicated field trial, pig slurry was applied at three rates (20, 40, and 80 m³ ha¯¹), which resulted in cumulative P inputs over the 8-year period of 628, 1256, and 2511 kg P ha¯¹. Slurry inputs of 20, 40, and 80 m³ ha¯¹ resulted in the accumulation of 368, 936, and 2039 kg P ha¯¹ in soil to 60 cm, respectively. A combination of soil storage (59–81 %), crop removal (7–14 %), and total P transfer in surface runoff (5–15 %) accounted for most of the P applied in pig slurry over 8 years. Our results highlight the potential environmental impacts of runoff P losses in long-term waste-amended and intensively managed subtropical coarse-textured soils. Measures to minimise soil erosion and P transfers from land to water bodies are of utmost importance

Nutrition, productivity and soil chemical properties in an apple orchard under weed management

Weed management in orchard may affect apple tree nutritional status and yield, N flow and other soil chemical properties. This study evaluated apple tree nutritional status and yield, N flow in soil and soil chemical properties in an apple orchard under different weed managements. The experiment was started in October 2011 in an apple orchard established in 2008, on 80 plants submitted to the following treatments: no weed management, weed desiccation in rows, weed mowing in rows and weed mowing in rows and interrows. In 2011/2012, 2012/2013, and 2013/2014 crop seasons, stem diameter, number of fruits per plant and yield were measured, and nutrient leaf concentrations were quantified. In 2012/2013 and 2013/2014 crop seasons, soil samples were collected from 0 to 0.20 m layers, in order to quantify NH4 ?–N and NO3 -–N. In September 2013, 24 months after beginning of the experiment, stratified soil samples were collected in the 0–0.025, 0.025–0.05, 0.05–0.10, 0.10–0.15, 0.15–0.20 and 0.20–0.40 m layers. Soil total organic carbon, pH, available P and exchangeable K, Ca, and Mg were measured. The weed management methods did not affect apple tree yield and growth and they had a small effect on nutrient concentrations in leaves and in soil. Row and inter-row weed management had little or no effect on competition with apple trees for water and nutrients. The weed management can be dispensed during the production cycle, reducing soil erosion, N losses and the use of herbicide