Modelling stochastic crop response to fertilisation when carry-over matters

Soils in a large part of Niger's agricultural area are sandy and very low in nitrogen (N), phosphorus (P) and organic matter. This low soil fertility combined with low and erratic rainfall constitutes a severe constraint on food cropping in the area. Although agronomists have advised chemical fertilization as a means of improving soil fertility, little fertilizer has been used in this area of the world. The economic management of soil fertility in the agricultural area of Niger is analyzed using a dynamic model of farmer decision-making under uncertainty. The model is based on agronomic principles of plant growth and accounts for the carry over of P, an immobile nutrient. At current input prices, a soil P content of at least 14 ppm is found to be desirable. This target is above the natural soil fertility level of about 3 ppm. It can be maintained with a moderate annual application (12 kg P₂O₅ ha^?1) of simple superphosphate. Results also suggests that returns to N fertilization are too low and variable to warrant the use of this input.     

LIVESTOCK PRODUCTION POLICIES AND MEAT PROCESSING MARGINS: THE CASE OF NEW ZEALAND, 1967-1988*

The New Zealand export meat industry has been through a considerable number of changes in the 1980s. The deregulation of export slaughter facilities, Supplementary Minimum Prices, Producer Board intervention, declining livestock numbers and domestic cost pressures have all affected the performance of the domestically based processing sector. Major changes in market access and demand have influenced off-shore marketing operations, particularly for sheepmeats. Additionally, there has been a change in the type of meat exported with a greater proportion of further processed product shipped in recent years. As an example of the impact of these developments on livestock producers, the producer share of the United Kingdom wholesale market return for a representative prime lamb carcase has fallen from 40 per cent in 1978 to 25 per cent in 1988. In this article the pattern of intervention in the New Zealand pastoral meat industries from the mid-1960s is detailed, emphasising the different environments of the beef and sheepmeat enterprises. Then the principal factors influencing domestic processing margins for these products are empirically examined. Alternative model specifications and alternative estimation techniques are compared and contrasted. The results of these analyses are discussed in terms of the historical patterns of assistance and structural change, and in terms of current rationalisation pressures on the meat processing sector.     

数据管理:电子商务数据的存储问题

许多情况说明，用于组织中数据存储的消费已经成爆炸状态。产生这种情况的主要因素是电子邮件和电子商务对数据的质量和数量的要求提高了，并且这种数据大部分是分散的、非结构性的，这就增加了对组织中数据管理的要求。本文是在澳大利亚进行的一次调查的基础上做出的，该调查是关于组织中如何处理数据增长和由于数据增长所带来的问题。调查的结果显示人们对该问题表现出高度的关注，同时显示出一种乐观的趋势，即技术将对未来出现的各种各样的问题提供解决方案。     

The Bias Due to Omitting Income When Estimating Demand Functions

This paper obtains an expression of the bias when relevant explanatory variables are omitted in seemingly unrelated regression (SUR) models. A simple demand system is provided to illustrate the direction of the bias terms when a variable is omitted.
L'article permet d'exprimer le biais qui résulterait de l'omission de variables explicatives pertinentes dans des modéles de régression sans corrélation apparente (SUR). Le système de demande simple qui est présente ici met en évidence le sens des éléments de biais lorsqu'on omet une variable.     

SOME OLD TRUTHS REVISITED

The primary objective in this paper is to 'promote' the use of equilibrium displacement modeling, or comparative static analysis of general function models, as a research tool in agricultural price and policy analyses. This is by no means a new tool, but it does seem to be used much less in Australia than it is in the US where it has been the basis of several important journal papers in recent times, The paper includes applications to: (a) reproduce important results obtained by Euse (1958) regarding total elasticities; and (b) examine the price premium argument that has been advanced in favour of single-desk selling arrangements. The latter is the secondary objective in the paper. Whilst equilibrium displacement modelling has its shortcomings, it is a research tool that can provide useful results with few assumptions. It can be a substitute for econometric modelling when resource and time constraints are binding. The application to the price-premium argument re-confirms the doubts that many analysts have expressed about single-desk selling.     

A continuing evolution in U.S. agricultural and food policy - The 1990 Act

This paper reports the results of a study of the economic content and the decision-making process of the recently adopted U.S. 1990 agricultural and food policy. It is the most comprehensive policy of its type. It represents the broadest participation of private individuals and interests groups, and will affect the economy of not only the United States, but also the ***economies of trading countries around the world. The study examines the economic conditions leading up to the policy, a theoretical foundation of public policy determinants, the role of economic analysis in that policy development, the provisions of the Act compared with the previous policy, and its extensive economic implications. Results of the study support features of a conceptual framework for economic policy of a participatory government. The study also reveals the unique policy process of the United States and the provisions of its price and income policy for the food and agricultural sector. Finally, this article identifies the interrelations between the 1990 policy and on-going GATT negotiations, the emerging importance of environmental and food quality issues in agricultural and food policy, and sources for further study of this Act.     

GOVERNMENT VERSUS PRIVATE QUALITY ASSURANCE FOR AUSTRALIAN FOOD EXPORTS

Most foodstuffs have quality attributes that are difficult to determine prior to purchase. Thus quality assurance is an inherent problem in food exporting. Private quality assurance can succeed if exporters can credibly signal that they have much to lose from cessation of purchases. If exporters do not provide credible quality signals, and foreign importers judge food quality according to country of origin, honest exporters can suffer negative spillovers from others' cheating under either government or private quality assurance. For both economic and political reasons, the best choice between government and private quality assurance will differ between foods and importing countries.     

OVER-REACTIONS IN US AGRICULTURAL COMMODITY PRICES

The purpose of this paper is to test rationality in agricultural commodity markets. We investigate the price-adjustment process after significant events using abnormally large cash commodity price changes as proxies for the arrivals of significant events in the markets. The evidence suggests that market rationality is violated. Generally, agricultural commodity prices tend to reverse after significant events. This is consistent with the over-reaction hypothesis which maintains that traders in spot commodity markets over-weight more recent information and under-weight prior information in their expectations.     

The law of one price: a test based on prices for selected inputs in New Zealand agriculture

The law of one price (LOOP) is an essential foundation of both the pure theory of trade and monetary theory. Strictly speaking, the law relates to prices of individual commodities. However, empirical tests of LOOP have often relied on aggregated data. In this paper, a model is derived and estimated using price data for 15 selected inputs in New Zealand agriculture. The results offer no support for the LOOP in the short run, and the results for the long run are mixed. It may be inappropriate, therefore, to assume that the LOOP holds generally in modelling exercises, particularly when models are used for policy purposes.