Food crops, exports, and the short-run policy response of agriculture in Africa

The response of agriculture to changes in relative prices is an important factor in the success of structural adjustment programs in Africa. In this paper I estimate supply functions for total agricultural output, food crops and export crops in 14 African countries for the years 1975 to 1990. Food and export crops are substitutes in production in the short run. Total agricultural output responds negatively to increases in export prices and positively to increases in food prices. A plausible explanation is that as farmers shift resources to export crop production, food supply falls in the short run, while the increase in export supply may take several years to materialize. The exchange rate is significant in explaining both food and export crop production and aggregate agricultural supply, suggesting that the exchange rate is acting as a proxy for excluded macroeconomic variables or that changes in the exchange rate are not passed immediately through to prices.     

Inter‐ and intra‐seasonal crop acreage response to international food prices and implications of volatility

Understanding how producers make decisions to allot acreage among crops and how decisions about land use are affected by changes in prices and their volatility is fundamental for predicting the supply of staple crops and, hence, assessing the global food supply situation. This study makes estimations of monthly (i.e., seasonal) versus annual global acreage response models for the world's principal staple food crops: wheat, corn, soybeans, and rice. Primary emphasis is given to the magnitude and speed of the allocation process. Estimation of intra‐annual acreage elasticity is crucial for expected food supply and for input demand, especially in the light of the recent short‐term volatility in food prices. The econometric results indicate that global crop acreage responds to crop prices and price risks, input costs as well as a time trend. Depending on respective crop, short‐run elasticities are about 0.05 to 0.40; price volatility tends to reduce acreage for some of the crops; comparison of the annual and the monthly acreage response elasticities suggests that acreage adjusts seasonally around the globe to new information and expectations. Given the seasonality of agriculture, time is of an essence for acreage response. The analysis indicates that acreage allocation is more sensitive to prices in the northern hemisphere spring than in winter and the response varies across months.     

FOOD SECURITY IN KWAZULU: RESULTS OF A HOUSEHOLD-BASED PROGRAMMING MODEL

A mathematical programming model of rural KwaZulu, excluding three northern districts, was developed to simulate agricultural production in regions of high and low cropping potential. This model aggregates enterprise levels predicted for four representative households of which two are in the high-potential region and two in the low-potential region. Several economic scenarios are simulated with the model to predict, inter alia, responses to changes in cereal prices, input subsidies, changes in off-farm employment and a rental market for crop land. Long-run food supply response is estimated to be inelastic with respect to changes in product and input prices. Higher food prices harm the majority of rural households. Lower input prices have little impact on household welfare. Conversely, it is predicted that a rental market for arable land could have a large positive impact on crop production and would improve household welfare.     

SOME ESTIMATES OF SUPPLY ELASTICITIES FOR NIGERIA'S CROPS*

The production of export crops or cash crops as they are called in developing countries is subject to various characteristics which affect supply and producer response relationships. For perennials such as cocoa, oil palms, rubber, and coffee which are produced in Nigeria, cultivation involves planting, gestation, removal, yield, replacement, rehabilitation, etc. For annuals such as cotton, groundnuts and soya beans exported from Nigeria, similar situations, excluding gestation and replacement problems, are involved. Models for estimating supply schedules and response must be complex and highly demanding in data in order to encompass these dimensions. The models developed in this study rest on the classical assumption of rational producers who respond positively to producer prices. Because of data limitations ordinary least squares (O.L.S.) regression is employed to develop three types of price elasticities of supply for six commodities - cocoa, palm oil kernel, groundnut, rubber and cotton. The results confirm the response to depressing pricing policies of the Marketing Boards in Nigeria and suggest policy implications of price and production incentives as positive means of enhancing improved production response designed to rejuvenate Nigeria's export crop industry under economic development.     

Expectations,supply response,and marketing boards: An example from Kenya

Whether farmers form price expectations adaptively or in a forward-looking manner has implications for supply response analysis and for the implementation of agricultural policy reform. This paper examines the formation of price expectations by Kenyan export-crop farmers who market their produce through a monopsonistic parastatal. The analysis allows for relaxation of the small-country assumption within a rational expectations framework. Production behavior is consistent with expectations of future prices based on indicators of aggregate supply and of the marketing board's purchasing capacity. The finding that price forecasts may be formed using information other than previous price levels implies that marketing reforms that raise prices may not raise the relevant price expectations. To elicit a positive supply response, market reforms should be sensitive to farmers' interpretation of institutional signals as well as previous prices.     

On the Use of Price Ratio in Aggregate Supply Response: Some Evidence from the Poultry Industry

The specification of supply/demand relationships has received considerable attention in agricultural economics (Heien 1977). Economic theory has helped provide a basis for the specification of such relationships, one of its contributions being the proposition that prices should be interpreted only in relative terms. This has had a profound influence on model building in agricultural economics, leading a number of researchers to avoid the use of absolute prices in economic analysis. For this reason, numerous market models of the agricultural economy use price ratios as explanatory variables (e.g., Chen; Chen et al.; Heien, 1976; Gerra; Kulshreshtha and Wilson; Rahn; Talpaz; Morzuck et al.; Houck and Gallagher; Wilson et al.); these examples suggest that the use of such ratios is fairly widespread in econometric modeling of the crop and livestock sectors. One of the best examples of price ratios is the "feed cost to price" ratio commonly used in the analysis of livestock supply response. Indeed, since feed cost constitutes a major part of the total production cost in livestock activities, the "feed cost to price" ratio is often considered a proxy for profitability. For this reason, data on such ratios are regularly published for various livestock activities (e.g., USD A). Also, "feed cost to price" ratios are often employed in the specification of models of livestock supply response, (e.g., Chen; Chen et al.; Heien 1976; Gerra; Kulshreshtha and Wilson; Rahn; Talpaz). However, not all models of aggregate supply response follow this approach. For example, Freebairn and Rausser, and Arzac and Wilkinson, use prices as separate variables rather than in ratio forms in their models. In particular, they do not employ price ratios in their livestock and crop supply equations. The existence of these different approaches raises questions about the appropriateness of the use of price ratios in the modeling of aggregate supply.     

The Impact of Cereal Prices and Policy on Crop Rotations and Supply Response

The impact of cereal prices on rotational decisions and farm‐level and industry cereal supply is considered. It is argued that with the voluntary 50 per cent set‐aside option for cereal producers, there is a large financial incentive to adopt a 50 per cent set‐aside cropping plan as cereal prices fall below an individual producer's ‘indifference’price. For a typical 210‐hectare UK combinable crop farm, adopting a 50 per cent set‐aside cropping plan is optimal when the price of cereals is below £62/tonne (98.50/tonne). If widely adopted, 50 per cent set‐aside will lead to a substantial fall in the supply of cereals and would lead the industry supply curve for cereals to move leftward and become more elastic over a certain price range. The level of reduced cereal supply will be greater than would be predicted from an estimate of industry level supply response that ignored rotational and farm‐level financial incentives.     

Estimating a Primal Model of Regional Crop Supply in the European Union

This article estimates behavioural parameters of the quadratic regional supply models in the modelling system CAPRI. Using the time‐series data in the CAPRI database, we directly estimate the optimality conditions using a Bayesian highest posterior density estimator. After discarding regions with insufficient data, parameters for up to 23 crop production activities with related inputs, outputs, prices and behavioural functions are estimated for 219 regions in EU‐27. The results are systematically compared with the outcomes of other studies. For crop aggregates (e.g. cereals, oilseeds, etc.) at the national level, the estimated own price elasticities of supply are found to be in a plausible range. On a regional level and for individual crops, the picture is much more diverse. As far as we know, there is no other study of similar regional and product coverage.     

NEGATIVE SUPPLY RESPONSE AND THE ROLE OF PRICE EXPECTATIONS IN A TWO-PERIOD MODEL OF CATTLE PRODUCTION

This paper incorporates a representation of producers' price expectations (ARIMA) in a two-period production process to characterise short-run cattle supply. The model provides a framework for examining the role of biological factors and changing expectations of future cattle prices in generating a negative short-run supply response. The biological link between cattle generations requires the farmer to make a decision between production today and production tomorrow. This decision is based on a trade-off between the possibilities of increasing current profit levels by increasing current output weighted against the possibilities of increased future profit by maintaining animals in inventory under the expectation of future price increases. Application of the model to Canadian data for the period 1978-81 shows that the necessary condition for a negative supply response exists, but that the total supply elasticity remains positive.     

Evaluating the impact of rising fertilizer prices on crop yields

Because of tensions on fossil energy and phosphorus markets, the rise in fertilizer prices observed during the last decades may continue in the future, putting into question production pathways relying heavily on crop intensification. To evaluate how, in this context, economic choices may alter crop yields, we first construct different fertilizer price scenarios to 2050 based on an econometric relation with oil and gas prices. Other possible scenarios, such as the continuation of historical trends, are also considered. The resulting changes in fertilizer price range between +0.8% and +3.6% per year over the 2005–2050 period. These scenarios are tested in a global land‐use model incorporating an endogenous representation of the land–fertilizer substitution. We find that the supply‐side response to rising fertilizer prices could lower crop yields in 2050 from ?6% to ?13%, with a corresponding increase in global cropland area ranging between 100 and 240 Mha if the demand for food and nonfood products has to be met. The sensitivity of these results is tested with regard to assumptions on food consumption, change in potential yield and nutrient use efficiency.     

Fighting global food price rises in the developing world: the response of China and its effect on domestic and world markets

This article addresses how China is being affected by and is responding to the world food crisis. So far, Chinese officials have responded to higher world prices by drawing down stocks and limiting exports of major grains. These policy instruments were not available for soybeans, so domestic prices of soy and other oilseeds have risen with international prices. Using a global CGE model, we show that the initial world price rise was largely due to higher world oil prices and demand for biofuels as opposed to other factors, especially in maize and soybeans. China's response to this shock has kept domestic grain prices low relative to world grain markets and to domestic soybean prices. As grain stocks are depleted, however, demand growth will push domestic prices back into alignment. Anticipating this pressure on consumers and accelerating supply response through public investment will facilitate adjustment.     

Estimation of Area Elasticities from a Standard Profit Function

This article demonstrates that both crop area and output elasticities can be calculated from a profit function. A Chambers/Just profit function (which includes land allocations as quasi-fixed factors) is used to derive shadow price equations for each crop area allocation. Jointly solving these shadow price equations for crop area makes it possible to calculate individual crop area elasticities. A profit function is specified to represent agricultural producers in the state of Iowa. Shadow price equations are jointly estimated with output supply and input demand equations. From these estimated equations, we derive the individual crop area response and output response to a change in prices.     

Rural credit and agricultural supply in Brazil

The objective of this study is to determine the financing impact of total expenditure on the use of agriculture inputs (fertilizers, labor, and pesticides), and the output of cotton, rice, beans, corn, soybean, and wheat in Brazil. We study the period 1976–2005. The analysis is based on duality applied to the production theory. The output supplies and conditioned input demands are estimated from a translog multi‐output, multi‐input restricted profit function, where the total production credit is used as proxy of the total expenditure. Farmer expectations with respect to crop prices are incorporated to the estimation based on the quasi‐rational expectation model. The output and input responses to the total expenditure are positive and statistically significant except for cotton, wheat, fertilizer, and pesticides. The short‐run output supply response to own prices is inelastic, except for wheat, which presents elastic response to its price. Acreage has a positive impact on the output supply and it is influenced by land productivity. The main conclusion is that farmers face budget restrictions to purchase inputs, and a government credit program might increase the agricultural supply.     

Canadian Hog Supply Response: A Provincial Level Analysis

Canada's hog sector has faced two decades of tumultuous growth, yet there are no recent estimates of supply response. This study uses state‐space methods to account for a multiplicity of autonomous structural changes impacting the sector and determines if the fundamental relationship between supply response and hog prices has changed from previous estimates. The results are consistent with prior research but offer the reader previously unavailable estimates of supply response with respect to feed prices and the variability of hog and feed prices. Feed price elasticities are somewhat larger than hog price elasticities. The effects of price risk for supply response appear quite muted but the impacts of feed price risk are greater than for hog price risk.     

POPULATION DYNAMICS AND MILK SUPPLY RESPONSE IN THE US LAKE STATES

This paper develops a dynamic model of a dairy cow population and of milk supply response. When applied to the US Lake States, the model provides evidence against the Nerlovian model. It suggests that the pattern of dynamic effects of prices on cow numbers varies for different prices. The estimated dynamic supply elasticities provide some useful information on the nature of dairy production adjustments. For example, the response of milk supply to market prices is found to be very inelastic in the short run. It takes at least 7 years of sustained change to obtain an elastic response to milk price. Also, feed price and slaughter cow price are found to have smaller effects on dairy supply than milk price, but larger effects than risk, hay price or capital cost.     

SUPPLY RESPONSE OF AUSTRALIAN WHEAT GROWERS

Alternative specifications of models of the supply response of Australian wheat growers and their economic implications are considered in terms of the existence and nature of production lags, and the choice between expected prices and expected gross returns as the preferred explanator of producers' response to changing economic conditions. The analysis indicates that there are lags which are due primarily to the difficulties and costs of rapid adjustment rather than to the time required to revise expectations. The statistical results were similar for the alternative specifications of gross margins and prices as the economic decision variables. However, the price elasticities derived using the gross margins specification were about a third of those using the prices specification. The gross margins specification yielded additional information in the form of yield and input cost elasticities.     

新一轮国际粮食价格上涨：原因及对中国市场的影响

[目的]随着中国粮食进口不断增加,国内外市场联系越来越紧密。2020年下半年以来,国际市场粮食价格快速上涨,对国内粮食市场产生一定影响,分析国际市场价格上涨的原因和影响对确保国内粮食供应稳定、保障国家粮食安全具有重要意义。[方法]文章分析了2019年以来小麦、大米、玉米、大豆4种粮食产品的国内外价格走势,从供需状况、贸易政策、气候变化等因素分析国际市场价格波动的原因,并探讨了国际价格对国内价格的影响。[结果]当前全球主要粮食品种供应充足,库存仍处于较高水平,此轮国际粮食价格上涨主要是受到美国等发达国家宽松的货币政策以及疫情后全球消费逐步回暖的影响;但国际市场价格上涨对中国市场的影响总体有限,国内小麦、大米、玉米价格上涨的主因是国内消费回暖和生猪产能恢复带动的饲用需求快速增长,油用大豆受国际市场的影响较大。[结论]为稳定国内粮食市场,避免国际市场的冲击,中国要进一步提升粮食综合生产能力,强化科技支撑,加强粮食储备管理,健全政策支持体系,并引导居民建立科学的消费观念。     

Agricultural Supply Response: A Survey

This paper surveys the literature on agricultural supply response to prices in developing countries. Empirical estimates of elasticities depend both on the methodology adopted and on country-specific factors relating to technology, economic structure and macro constraints. The paper seeks to establish some general conclusions on supply responsiveness within these limitations. Supply response to output prices at the aggregate and at the crop levels is considered first. Crop-specific acreage elasticities range between zero and 0.8 in the short run while long-run elasticities tend to be higher — between 0.3 and 1.2. Yield elasticities are smaller and less stable than acreage elasticities. Clearly, inter-crop pricing can be relied upon to effect shifts in the commodity composition of agricultural output. Evidence also suggests that supply elasticities vary systematically with such factors as price and yield risks, multiple-cropping, the importance of the crop, farm incomes, farm size, tenancy and literacy. The most controversial and important aspect of supply response is the effect on aggregate agricultural output of agriculture's terms of trade. Conventional time-series estimates range from 0.1 to 0.3. A major cross-country study reports an aggregate elasticity as high as 1.66. It is argued that cross-country estimates are apt to exaggerate aggregate responsiveness while time-series studies underestimate it somewhat. For LDCs, a tentative range of 0.4 to 0.5 seems plausible. Hence, the distributive effects of the terms of trade are likely to be more significant than the allocative effects. Asian evidence shows that only a third of the inter-country differences in fertilizer use can be attributed to fertilizer price policies. Provided new technologies and infrastructure are in place, fertilizer subsidies can help in technology diffusion and in overcoming credit constraints. The choice between price supports and input subsidies will depend on a variety of country- or situation-specific factors. Nevertheless, a significant general factor favoring price supports is that they can more easily be coupled with price stabilization goals than input subsidies. Though sparse, the available evidence on the response of marketed surplus suggests that price policy is not a reliable instrument for regulating inter-sectoral trade.     

基于Logistic模型的东北地区粮食生产能力影响因素研究——以宾县为例

[目的]粮食生产能力关系到粮食供给和国家粮食安全,如何提高粮食生产能力是我国亟待解决的问题。文章以宾县为例,通过一定的方法探索粮食生产能力的影响机制,最终提出提高粮食生产能力的合理建议。[方法]利用农户调查数据,借助Logistic模型探讨自然因素和社会经济因素对粮食生产能力的影响特点。[结果](1)品种技术推广、作物收益对粮食生产能力的影响效应在1%水平上达到显著;(2)生育期变化、土地质量、旱灾、耕作方式对粮食生产能力的影响效应在5%水平上达到显著;(3)温度、降水、冷害及农业生产资料投入对粮食生产能力的影响效应在10%水平上达到显著;(4)温度与降水是否集中在生育期内、出售情况、农业引导政策对粮食生产能力的影响不显著。[结论]针对研究结果,该文提出,可从预防低温冷害、健全水利设施、完善耕地保护制度及加强农业基础设施建设等方面提高粮食生产能力。     

Incorporating risk in the economic analysis of agronomic trials: fertilizer use on barley in Syria

In the drier areas of Syria yields of barley, the principal crop, are low. Due to the variability in rainfall, fertilizer use is perceived as risky. Barley-fertilizer trials have been conducted on farmer's fields over a period of four years to investigate whether the large yield response to fertilizer observed on research sites could be achieved under farmers' conditions. Data were pooled across years and sites and response functions estimated. Simple optimization analysis shows that economic optimum fertilizer rates vary considerably with rainfall and relative prices. Historical rainfall data are combined with the estimated response functions, and stochastic dominance analysis is used to compare the riskiness of fertilizer treatments in terms of net benefits and benefit-cost ratios. Results show that, given the estimated expected rainfall in barley producing areas, fertilizer use, especially at low levels, may not be as risky as has been believed. Extensions of the methodology to include other environmental variables, or to target recommendations, are discussed.