phosphorus

Bijeenkomst: EGF2015
Auteur: Albrecht K.A., Ochsner T.E., Schwab A.R. and Jokela W.E.
ISBN: 978-9090-289-61-8
Jaar van uitgifte: 2015
Producttype: Paper
Maize (Zea mays L.) silage has become an increasingly important forage crop in high output dairy farming systems in Europe and North America because of its high energy density, relatively uniform nutritive value, and efficiency of production. But due to lack of surface residue and organic matter inputs and high nitrogen (N) fertilizer inputs, maize silage production is one of the most demanding cropping systems imposed on our soil and water resources. We investigated intercropping maize with the persistent rhizomatous legume, Caucasian clover (Trifolium ambiguum M. Bieb.), as a means to provide continuous living groundcover to minimize nitrate leaching, nutrient runoff and soil erosion. Maize was sown into existing stands of Caucasian clover that had been suppressed to reduce competition, and into areas with no clover. Total nitrate-N leached was reduced by 74% relative to the control monocrop maize under intercropped maize silage. On loess soils with 8 to 15% slope, during simulated, short, heavy rainstorms, Caucasian clover intercrop reduced water runoff by 50%, soil loss by 77%, and P and N losses by 80% relative to monocrop maize. Intercropping maize with Caucasian clover can eliminate N-fertilizer inputs and greatly reduce negative environmental impacts associated with maize silage production.

Bijeenkomst: EGF2015
Auteur: D’Haene K., De Vliegher A. and Hofman G.
ISBN: 978-9090-289-61-8
Jaar van uitgifte: 2015
Producttype: Paper
Algal blooming caused by phosphorus (P) losses from agricultural soils to ground- and surface water is a major problem as P is typically the limiting factor for eutrophication in freshwater systems. To fine-tune the advice on P fertilisation and increase P-use efficiency, it is important to have up to date information on amounts of phosphate (P2O5) exported by crops. We re-analysed Flemish nitrogen fertilization experiments on silage maize (Zea mays) and cut grassland (Poaceae) to derive their quantities of exported P2O5. The median P2O5 export by silage maize increased significantly from 78 kg P2O5 ha‑1 in the last decade of the 20th century to 94 kg P2O5 ha‑1 in recent years (median of 2.1 g P kg‑1 dry matter (DM)). This increase is due to the higher crop yields. The median P2O5 export for cut grassland remained at approximately 110 kg P2O5 ha‑1 with a median of 4.1 g P kg‑1 DM.