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Introduction
Soil quality, which refers to the soil’s capacity to support crop growth without resulting in soil degradation or otherwise harming the environment (Gregorich & Acton, 1995), is a critically important component of sustainable agriculture (Miller & Wali, 1995; Warkentin, 1995; Subbian et al., 2000). It is vital both to the production of food and fibre, hence to the soil’s productive capacity, as well as to the health of the ecosystem (Pierzynski et al., 1994). Maintenance and improvement of soil quality may, therefore, be a key strategy to meet the ever-growing demand for food and to address the increasing concern of environmental quality (Carter et al., 1997).
Soil quality is a composite of, and to a large extent determined by, chemical and biological properties of the soil. These properties not only are important for the soil’s function as a medium for plant growth, but also influence its service as a buffer in the formation and destruction of hazardous compounds (Larson & Pierce, 1994). They are essential attributes on which the soil’s productive capacity and its role as an environmental moderator depend (Acton & Padbury, 1993; Bezdick et al., 1996).
Consequently, maintenance and enhancement of soil quality are, in essence, dependent upon improvement of chemical and biological properties of the soil. As any alteration in quality of the soil is manifested in these properties, they are also useful indicators of quality change (Doran et al., 1996).
Soil quality is highly influenced by soil management practices (Larsen & Pierce, 1994). Management-induced deterioration in soil quality has affected nearly 40% of the World’s agricultural land (Oldeman, 1994) and is one of the basic agricultural problems today threatening the long-term sustainability of agroecosystems (FAO, 1990). Decline in soil quality is often a result of management practices that cause loss of organic matter, depletion of nutrients and/or reduction in activity and species diversity ofmicroorganisms (Oades & Walters, 1994; Riffaldi et al., 1994; Giller et al., 1997). Soil quality can be maintained or enhanced by appropriate restorative measures such as legume-based crop rotation, manure addition and other management practices that improve chemical and biological properties of the soil (Lal, 1997; Carter, 1998).
Chapter General background
1.1 Introduction
1.2 Hypothesis
1.3 Specific objectives
1.4 References
2 Soil chemical and microbial properties in relation to crop rotation and fertilization: a review
2.1 Introduction
2.2 Crop rotation and its effect on chemical and microbial properties of soil
2.2.1 Effect on soil chemical properties
2.2.2 Effect on soil microbial properties
2.3 Fertilization and its effect on chemical and microbial properties of soil
2.3.1 Effect of manure
2.3.1.1 Soil chemical properties
2.3.1.2 Soil microbial properties
2.3.2 Effect of NPK fertilizers
2.3.2.1 Soil chemical properties
2.3.2.2 Soil microbial properties
2.4 Interactive effects of crop rotation and fertilization
2.5 References
3 Influence of residual manure on selected nutrient elements, microbial properties and maize yield under long-term crop rotation
3.1 Introduction
3.2 Materials and methods
3.2.1 Site description
3.2.2 Experimental design
3.2.3 Sampling and analysis
3.3 Results and discussion
3.3.1 Total organic C, total N and available P
3.3.2 Soil microbial biomass C, N and P and microbial number
3.3.3 Maize grain yield
3.4 Conclusion
3.5 References
4 Effect of direct N and K and residual P fertilizers on soil chemical properties, microbial components and maize yield under long-term crop rotation
4.1 Introduction
4.2 Materials and methods
4.3 Results and discussion
4.3.1 Total organic C, total N and available P
4.3.2 pH and basic cations
4.3.3 Soil microbial biomass and numbers
4.3.4 Maize grain yield
4.4 Conclusion
4.5 References
5 Soil nutrient contents, microbial properties and maize yield under long-term crop rotation and fertilization: a comparison of residual manure and NPK fertilizers
5.1 Introduction
5.2 Materials and methods
5.3 Results and discussion
5.3.1 Total organic C, total N and available P
5.3.2 Carbon and N inputs
5.3.3 Soil microbial biomass and numbers
5.3.4 Plant N and P concentration
5.3.5 Maize grain yield
5.4 Conclusion
5.5 References
6 Effect of supplemental N and K on the residual value of manure and P to soil chemical properties, microbial components and maize yield under long-term crop rotation
7 Summary and general conclusion
