The effect of co-composted cabbage and ground phosphate rock on the early growth and P uptake of oilseed rape and perennial ryegrass

• Published in: Journal of plant nutrition and soil science Vol. 175; no. 4; pp. 595 - 603
• Main Authors: Walker, Robin L., Edwards, Anthony C., Maskell, Phillip, Watson, Christine A., Rees, Robert M., Knox, Oliver G.G., Stockdale, Elizabeth A.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01-08-2012; WILEY‐VCH Verlag; Wiley-VCH
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Brassica napus L; Brassica oleracea L; compost; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Lolium perenne L; organic farming; Other nutrients. Amendments. Solid and liquid wastes. Sludges and slurries; Soil science; Soil-plant relationships. Soil fertility; Soil-plant relationships. Soil fertility. Fertilization. Amendments; Monocotyledones; Brassica napus L; Brassica napus var. oleifera; Growth; Cruciferae; Gramineae; Dicotyledones; Phosphate rock; Angiospermae; Soil science; Lolium perenne; C3-Type; organic farming; Non metal; Production system; Brassica oleracea L; Compost; Vegetals; Early phase; Lolium perenne L; Phosphorus; Nutrient uptake; Alternative agriculture; Group VA element; Composting; Brassica oleracea; Vegetable crop; Organic agriculture; Brassica napus; Herbaceous plant; Spermatophyta; Soil plant relation; Oil plant (vegetal)
• ISSN: 1436-8730; 1522-2624
• DOI: 10.1002/jpln.201100124

Phosphorus (P) availability to crops in organic systems can be a major issue, with the use of readily available forms often restricted. One product that can be used in organically managed systems, that is also relatively easily accessible to growers, is phosphate rock, although its solubility and therefore crop availability is often poor. One possible approach to improve this situation is co‐composting phosphate rock with selected organic waste materials. Various ratios of phosphate rock and cabbage (Brassica oleracea L.) residues were co‐composted and the products tested at different rates of application. The effects were assessed over 12 weeks using oilseed rape (Brassica napus L.) and perennial ryegrass (Lolium perenne L.) as bioassay crops in a pot experiment. At harvest, estimates of P derived from cabbage and phosphate rock for the lowest of two rates of compost were ≈ 2 and 10 mg P pot–1 for oilseed rape, compared to 5 and 2 mg P pot–1 for perennial ryegrass, respectively. Roots tended to have higher P concentrations than shoots. The crops showed differences in their abilities to access various P sources, with oilseed rape effectively taking P from phosphate rock, whereas perennial ryegrass was more effective at accessing cabbage‐derived P (the main substrate in the compost). Oilseed rape was able to take up 20% of the total P applied as phosphate rock, whereas perennial ryegrass took up less than 5% of the total P applied from this material. Both pre‐ and post‐application solubilisation/transformation mechanisms were involved in supplying plant‐available P. Quantifying the relative contribution from individual P sources remains problematic even within this relatively simple system.