Effect of organic fertilizers on biological parameters influencing soil quality and productivity ( Book Chapter)

Abstract

Intensive agriculture is one of the main activities causes for relatively high fertilizer and pesticide inputs. Intensive use of soil for years, together with inappropriate production technologies like continuous soil removal and the widespread use of pesticides and fertilizers, has created in many cases major problems of pollution and soil degradation. Thus, the need to minimize environmental impact without reducing yields makes it imperative to look for best-bet alternatives that achieve a sustainable production. Studies indicate that the key to sustainable agricultural production and long -term productivity of agroecosystems are processes that maintain organic matter in the soil. Apparently, soil application of organic fertilizers is a management strategy that would help in counteracting the progressive loss in organic matter both in the short and longterm. The addition of organic fertilizers improves soil physico-chemical, biochemical and microbiological properties and thus positively influences soil quality and plant productivity parameters. Organic amendments can also promote plant health, and it is also possible to obtain equivalent or even increased yields through organic production. The chapter focuses on the effects of organic manures on sensitive biological parameters (soil microbial biomass C, soil respiration, metabolic quotient, enzyme activities) that can be used as potential indicators for monitoring changes in quality of cropped soils. The responses of these parameters to organic manuring are discussed due to the fact that soil quality is strongly influenced by biologically mediated processes (nutrient cycling, nutrient capacity, aggregate stability) and also because it is important to identify those components that rapidly respond to changes in soil quality.