Soil fertility and productivity

To maintain soil fertility and productivity and prevent land degradation, nutrients taken up by crops must be replenished through the application of fertilizers. The use of fertilizer results in many benefits to producers, consumers, and the environment, starting with... 

On cultivated soils located on hilly or rolling landscapes, water erosion can reduce soil fertility and productivity to such an extent during periods of 25 years or less that cultivation is no longer profitable. Such erosion occurred on millions of acres in the East, Southeast, and even in many Midwest and Western soils. In many areas practically none of the original topsoil now remains. It is only the availability in recent years of abundant fertilizers that has made possible the use of many of these severely-eroded soils for general farm crops (see Chapter 26). Other soils that were originally very shallow are now classed as marginal and suitable only for pasture and forests. 

Sofl organic matter has, since the dawn of history, been the key to soil fertility and productivity. In the earlier years, as nomadic populations moved about in search of places where they could settle down and till the soil, they selected the soils that were most productive, and this meant highest in organic matter, even though they may not have recognized this fact. They knew almost nothing about soil organic matter, or how it functioned, but they reaped the benefits of it. 

Of equal importance to the public health are hazards of acute or chronic poisoning of farm animals and poultry insecticide residues in fruit, vegetables, meat, or dairy products phytotoxicity reduction of soil fertility and disturbance of the balance of nature through selective destruction of wildlife. These latter hazards are largely the responsibilities of agriculturalists and conservationists but are mentioned here for completeness. 

Yield is not the only indicator of farm productivity. Inputs used to deliver those yields should also be considered, and can be in the form of materials, as discussed below, but they may also be in different forms. For example, one way to manage soil fertility and pest problems on organic farms is to employ a different rotation from that on conventional farms where synthetic fertilisers and pesticides can perform those tasks. Because of the difference in rotation, which may also mean a larger diversity of crops, the whole farm needs to be considered when determining productivity and profitability. 

Granstedt, A. and Kjellenberg, L. 1997. Long-term field experiment in Sweden effects of organic and inorganic fertilizers on soil fertility and crop quality. In Lockeretz, W. (ed.) Agricultural Production and Nutrition. Tufts University, Boston, pp. 79-90. 

Organic production systems are complex out of necessity, since soil fertility and plant protection are provided by applying the principles of ecology and lessons from natural ecosystems. It is this complexity, in part, that makes the need for unique education and training opportunities so important for organic farmers. In addition, the lack of institutional support with information from universities and government agencies in most countries makes this a valuable area to explore and for which to seek appropriate educational options. 

McSorley, R., Ozores-Hampton, M., Stansly, P.A., Conner, J.M. Nematode management, soil fertility, and yield in organic vegetable production. Nematropica 1999 29 205-213. 

The potential of plant biomass transfers to contribute to soil fertility and crop nutrient supply will ultimately not only depend on land availability and vegetative productivity, but also on the availability of labour and capital for collection, transport and mulching. When considering issues of sustainability, it must be kept in mind that concentrating nutrients from a large area on a smaller area deprives most of the land of its fertility. 

Henao, J. and C. Baanante (2006) Agricultural production and soil nutrient mining in Africa.- Excerpt from Technical Bulletin Agricultural production and soil nutrient mining in Africa - Implications for resource conservation and policy development.- International Center for Soil Fertility and Agricultural Development, IFDC. Muscle Shoals, USA. 

Ecosystem productivity is an index integrating the cumulative effects of many processes and interactions which proceed simultaneously in the system. Whether or not a relation exists between soil fertility and forest productivity is still under discussion (Proctor 1992, Silver 1994, Thompson et al. 1992). There is, however, no doubt that soil fertility influences input/output budgets, and that soil fertility influences the rate of recovery of the forest ecosystem after disturbance (Bruijnzeel 1992). 

Erionite is not known to be currently mined or marketed for commercial purposes. Natural erionite has been replaced by synthetic nonfibrous zeolites. However, erionite was used as a noble metal impregnated catalyst in a hydrocarbon-cracking process, and erionite-rich blocks was also used for house building materials. Its use to increase soil fertility and to control odors in livestock production has been studied. 

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