Optimising phosphorus use in Victoria

Gourley, C.J.P. Dr; Ph: (03) 5624 2222; Fax: (03) 5624 2200; gourleyc@dri.agvic.gov.au

Research organisations: Victorian Department of Natural Resources and Environment; Dairy Research Institute, Ellinbank, RMB 2460, Warragul Vic 3820

Collaborators: Dr Peter Sale (La Trobe University); Prof. Robert White (University of Melbourne); Prof. David Chapman (University of Melbourne); Mr Euie Havilah (NSW Agriculture); Mr Nigel Fleming (South Australian Research and Development Institute); Mr David Campbell (Pivot Ltd); Mr Larry King (Pivot Ltd); Mr Jeremy Gittens (Pivot Ltd); and Ms Kathy Lescom (Pivot Ltd)

Sponsor: DRDC, Dairy Research and Development Corporation

Objectives:

1. To define the milk production response surface for P fertilizer and stocking rate;

2. To correlate detailed soil, plant and animal measurements with P fertilizer and stocking rate effects on milk production;

3. To compare the optimum P fertilizer requirements determined in the farmlet experiment with recommendations based on pasture dry matter responses using a traditional fertilizer test strip trial and a range of current fertilizer prediction models;

4. To measure the effect of important soil and plant characteristics on a range of soil types in dairy farming regions of southeastern Australia;

5. To assess the environmental impact of a range of P application rates and stocking rates;

6. To achieve a widespread transfer of information and adoption of the project results.

Methodology:

1. A farmlet study has been established with combinations of stocking rates of two, three and four cows/ha and fertilizer rates of 0, 35, 70 and 140 kg P/ha. Detailed measurements of soil, pasture, animals and the environment will be undertaken throughout the experiment;

2. Soil biological, physical and chemical techniques were used to assess the interaction between soil and fertilizer P on a broad range of soils;

3. Validation and demonstration sites were established on a number of key soil types in dairy farming regions of southeastern Australia;

4. Two PhD students investigated mechanisms of drought and defoliation tolerance under differing P regimes and the effects of stocking rates on nitrogen fixation by white clover.

Progress: The PhD thesis entitled 'Phosphorus supply and the tolerance of frequently defoliated white clover (Trifolium repens L.) to water deficit stress', was submitted by Mr D.K. Singh to La Trobe University in May 1998.

Period: starting date 1995-07; completion date 1998-06

Status: completed

Keywords: pastures, phosphorus fertilisers, optimisation, stocking rate, milk production response, drought tolerance, defoliation tolerance

Publications:

Singh, D.K. and Sale, P.W.G. (1997). Defoliation frequency and the response by white clover to increasing phosphorus supply 1. Leaf dry matter yield and plant morphology responses. Australian Journal of Agricultural Research 48, 111-118.

Singh, D.K. and Sale, P.W.G. (1997). Defoliation frequency and the response by white clover to increasing phosphorus supply 2. Non-structural carbohydrate concentrations in plant parts. Australian Journal of Agricultural Research 48, 119-124.

Singh, D.K., Sale, P.W.G.and McKenzie, B.M. (1997). Water relations of white clover (Trifolium repens L.) in a drying soil, as a function of phosphorus supply and defoliation frequency. Australian Journal of Agricultural Research 48, 675-681.