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Imprint
Quantification of weed competition in organically grown vining peas under field conditions
Project
Project code: 06OE126
Contract period: 01.04.2007
- 31.10.2008
Budget: 33,389 Euro
Purpose of research: Applied research
The yield of organically grown vining peas is often unsatisfactorily low. Besides soil borne diseases, weed competition is expected to be one of the main reasons. Weed control in organic vining peas is commonly done by harrowing, although it is proven that hoeing and ridging up are the more effective techniques. Because farmers assume only small yield effects of weed competition, the greater expenses associated with hoeing and ridging up are avoided and therefore these techniques are only rarely applied. Information on the yield response of vining peas to weed occurrence deriving from on farm investigations is very scarcely found in literature. Due to this lack of knowledge, the efficiency of the doubtlessly more cost intensive but more effective mechanical weed control techniques can hardly be estimated. Hence the aim of the biennial project was to quantify weed-caused yield losses on farmers' fields. Furthermore, nutrient balances of the pea crops were calculated to improve databases for nutrient removal. For this purpose, plant samples were analyzed for their concentrations of N, P, K and Mg and biological N2 fixation was measured using the 'extended difference method'. Weed density after commonly practiced harrowing ranged from 26 to 700 plants/m² with an average of about 250 plants/m². In comparison to control plots, which were manually kept free of weeds, yield reduction amounted to 0 to 49 % averaging 15 %. Relationships between the reduction in crop yield and weed biomass revealed a weed dry matter threshold of 40 g/m² at pea harvest, below which no yield losses occurred. The biological N2-fixation of the pea crops was to some extent depending on yield and nitrogen supply and ranged from 0 to 69 kg N/ha. The K- and Mg-concentrations of the peas were in accordance with values reported in the literature, while the P-concentration was always higher and the N-concentration lower. The N-content in harvest-residues was found to be strikingly low.
Section overview
Subjects
- Crop Protection
- Organic Farming
Framework programme
Federal Organic Farming Scheme and other forms of sustainable agriculture (BÖLN)
