The Value of Variable Rate Technology: An Information-Theoretic Approach

We present a theoretical treatment of the economics of variable rate technology and its interplay with information. The framework facilitates description of on-farm empirical profitability studies of variable rate nitrogen application on Illinois cornfields. We estimate site-specific ex ante economically optimal nitrogen application rates, and the value of site-specific information in the management of variable rate technology. We find that with site-specific information provided free, variable rate nitrogen application would have been profitable in six of eight fields. Because private markets are unlikely to provide such information sufficiently, more public funding of long-term, multiregion, multiyear experimentation is appropriate. Copyright 2009, Oxford University Press.

A risk assessment of sulphur deficiency in cereals using soil and atmospheric deposition data

A qualitative model was used to assess the risk of S deficiency in cereals in Britain. A risk index was generated for each of 6301 soil data points by considering the inputs of S from atmospheric deposition, the content of soil organic matter, and factors influencing the potential leaching of sulphate, i.e. soil type, texture, pH and annual rainfall. The results show that currently 11% of the British land area is at high risk of S deficiency, and a further 22% at medium risk. The high risk areas are in south-east Scotland, the Scottish Borders, East Anglia, the Welsh Borders and south-west England. These agree well with the distribution of reported incidences of S deficiency in cereals. If the UK target for reduction in SO2 emissions by the year 2003 is met, the model predicts that the high and medium risk areas will increase to 23 and 27%, respectively. Thus, agricultural use of S-containing fertilizers is likely to increase in importance in the near future