【正文】 ginal physical product of fertilizer in the different areas. Unfortunately, such data is often not available. As a result, other statistics are often used. A statistic that is monly used is average yield, with regions with a high average yield receiving more fertilizer. In the example above, average yield will not give the correct result. Since the high yield region has the smaller MPP, allocating more potash to this region would in fact reduce profits.　　總之，用平均產(chǎn)量不能為肥料在地區(qū)之間合理分配提供正確指導，原因是產(chǎn)量和邊際產(chǎn)量沒有關(guān)系，無論正負。有時，高產(chǎn)伴隨著高邊際產(chǎn)量。如果某個地區(qū)很肥沃，又或許由于肥料運作系統(tǒng)中存在一些限制因素而化肥用量不大，那就會出現(xiàn)這種情況。相反，高產(chǎn)常與低邊際產(chǎn)量相聯(lián)系，這是大量使用化肥的結(jié)果。　　In general, the use of average yield will not provide the correct guidelines for the allocation of fertilizer among regions. The reason is that there is no relationship, postive or negative, between yield and marginal physical product. Sometimes a high yield will be associated with a high marginal product. This would be the case if an area is particularly fertile and chemical fertilizers are not being used to any great degree, perhaps because they are not available due to constraints in the fertilizer system. Conversely, a high yield can be associated with a low marginal physical product. This would be the case if the high yield was a result of the heavy use of chemical fertilizers.　　上述討論假定各種化肥的總量是固定的，所能做的只是在農(nóng)戶之間或地區(qū)之間對肥料進行重新分配。這在短期內(nèi)是可行的，從長遠來說，在各種不同的肥料之間對肥料預算進行重新分配是可能的?！　he discussion above assumes the amount of the various fertilizers is fixed and that all that could be done is to reallocate the fertilizer among different farmers or among different regions. While this may be true in the short term, over the longer term, a redistribution of the fertilizer budget among different fertilizers may be possible.　　如果是這樣，從購買N肥和P肥的資金中抽出一部分來購買K肥，利潤就可能會增加。因為測定出氮肥（至少在高產(chǎn)地區(qū)）和磷肥用量與最高利潤水平相比相對過高。因而就其本身來說，減少這兩種肥料用量也能提高利潤。將此購買氮磷肥的錢用于鉀肥還能增加利潤?！　f this is the case, profits could be increased by taking some of the budget used for the purchase of nitrogen and phosphate and using it to purchase additional potash. This follows because it was determined that both nitrogen (at least in the high yield region) and phosphate are being overused relative to the level that would maximize profits. Thus, a reduction in the use of these fertilizers would, by itself, increase profits. Allocating the yuan spent on nitrogen and phosphate to potash would result in yet another increase in profits.　　因為上例中氮磷肥用量過高，所以考慮的解決方案相對比較簡單。一般來說，解決涉及不同肥料的問題需要了解各種肥料的價格，需要用前面推導出的關(guān)系，即　　MPPN/MPPK=rN/rK 　　While the solution to the above example is relatively simple to conceptualize because of the overuse of nitrogen and phosphate, in general the solution to problems involving different fertilizers requires knowledge of fertilizer prices. More specifically, it is necessary to use the relationship that was derived earlier, namely 　　MPPN/MPPK=rN/rK　　當然，問題也可能比只在不同肥料間重新分配資金復雜得多。例如，早稻并不是唯一需要化肥的作物，當可以種植其它作物時，就產(chǎn)生了如何在不同作物之間合理分配肥料的問題。這類問題的解決，涉及到重新分配資金，要使用下面的關(guān)系式：　　P1?MPPN/rN=P2?MPPK/rK　　Of course, the problem is even more plex than simply reallocating fertilizer expenditures among different fertilizers. For instance, early rice is not the only crop that requires fertilizer. When other crops can be grown, the question of the proper allocation of fertilizer among the crops arises. As was pointed out in the theoretical discussion, the answer to this type of question requires reallocating expenditures so that the following relationship holds. 　　p1MPPN/rN=p2MPPK/rK 　　確定肥料該如何分配，需要利用產(chǎn)品和肥料價格以及肥料在不同作物上的邊際產(chǎn)量等資料。　　This means that data on the prices of the outputs and the prices of the fertilizers, as well as the marginal physical product of fertilizer on each of the different crops is required to make an assessment of how fertilizer should be allocated.　　從長遠看，如果經(jīng)費不受限制，應該考慮不同肥料在不同作物間的分配，即考慮達到最高利潤的肥料用量。確定最適肥料分配方案的原則在肥料經(jīng)濟學（Ⅰ）中已進行了概述。肥料的最佳分配應考慮不同肥料之間的平衡，使每一種肥料的價格都等于該肥料的邊際產(chǎn)值。由于任何一種肥料的用量均會影響其他肥料的邊際產(chǎn)值，因此，一種肥料的最佳用量不能在不考慮其他肥料的情況下單獨選定。比如，在上述例子中，增施鉀肥可能會增加氮肥和磷肥的邊際產(chǎn)值，因而氮肥和磷肥的用量也需要提高。同樣，增施其他肥料如硫肥，有可能會提高氮、磷和鉀肥的邊際產(chǎn)量，因此需要進一步增加這幾種肥料的用量。實現(xiàn)這些肥料之間的真正平衡施用有賴于對產(chǎn)量函數(shù)特征的全面了解?！　n the longer run, it may also make sense to consider the allocation of different fertilizers among different crops when budgets are not constrained。 that is, to consider the question of what is the quantity of fertilizer that maximizes profits. The rules for determining optimal fertilizer allocation were outlined in Economics of Fertilizer I. Recall from that lecture that the optimal allocation of fertilizer involves balancing the different fertilizers so the price of each fertilizer equals the marginal value product of that fertilizer. Since the quantity of any one fertilizer influences the marginal value product of the other fertilizers, the optimal quantity of a particular fertilizer connot be chosen independently of the other fertilizers. Thus, for instance, in the example above, it may be the case that increased use of potash will increase the marginal value products of nitrogen and phosphate, thereby requiring an increase in their use as well. Similarly, provision of a deficient nutrient like sulphur may raise the marginal products of nitrogen, phosphate, and potash, thus requiring increased levels of these nutrients. The exact balance among the fertilizers depends on a full knowledge of the nature of the production function.　　本講座要強調(diào)的觀點是：無論供應充足與否，合理分配肥料資金需要知道不同肥料對增產(chǎn)的作用、各種肥料在決定產(chǎn)量時的相互作用以及產(chǎn)品和肥料的價格?！　he point to stress in this lecture is that the data requirements for a proper allocation of fertilizer expenditures whether constraints are present or not ? requires information on the response of yields to different fertilizers, the interaction among different fertilizers in determining yield, and the prices of the outputs produced and the fertilizers used.　　當存在限制因素，這是常有的事，肥料種類和購肥資金要在機會成本概念的指導下進行重新分配。實際上，只要資源（如肥料）供應是有限的，機會成本的概念就很重要?！　hen constraints are present, as is often the case, the proper allocation of fertilizer and fertilizer expendi