This paper presents a linear programming model designed to evaluate the impact of changes in milk to milk-quotaleasing price ratios, nitrogen fertiliser and concentrate prices on the pro®tability of a technically ecient UK dairy farm. The model incorporates energy and protein requirements of cows of di€erent yield levels and allows substitution between forage and concentrate feeds. The results...

Fertiliser recommendations for sugarcane are made with a view to achieving maximum probable yields based on response data derived from decades of research by the South African Sugar Association Experiment Station (SASEX). Adaptations are made according to the experience and knowledge of consultants, but the risks of under or over fertilising are seldom quantified in monetary terms. To address t...

Application of fish sludge as fertiliser to agricultural land can contribute to closing nutrient cycles in fish farming. The effect of different treatment technologies on the nitrogen fertilisation effects of fish sludge was studied by a bioassay with barley (Hordeum vulgare), an incubation and a field experiment. Dried fish sludge resulted in relative agronomic efficiency of 50-80% compared wi...

Standard nutritional advice for irrigated sugarcane in South Africa and Swaziland is based on soil sample analysis and threshold values that have been determined experimentally over many years with surface-applied fertilisers. Fertilisers are normally applied in solid form during the early stages of crop development and watered in by the next irrigation cycle. The increasing popularity of subsu...

A rapid screening (hydroponic) and field testing programme There is increasing interest in improving the nitrogen (N) use efficiency of cultivated crops, due to the high cost of synthetic N fertiliser. Since existing differences in N use efficiency between sugarcane varieties could be exploited to improve N fertilisation, a hydroponic pot experiment was conducted to test the performance of seve...

Seedlings of five native tussock species grown in the glasshouse on mountain subsoil showed outstanding responses to nitrogen and phosphorus fertiliser in combination. The most vigorous species was silver mssock but this produced less dry matter than an introduced grass, Yorkshire fog, grown on the same soil. Tussocks in general responded positively to applications of magnesium and potassium bu...

Introduction At a global scale, human activity has increased the flux of N two-fold (Vitousek et al. 1997), particularly driven by large scale fertiliser manufacturing (Fowler et al. 2013). Additionally, the ability to transport inputs and outputs cheaply and extensively has led to substantial growth in agricultural production over the past 50 years with an accompanying 40% increase in world po...