Matching fertiliser inputs of both macro- and micronutrients to crop target yield and quality will maximise the crop’s competitive ability against weeds. Efficient use of crop residues and animal waste are useful for improved nutrient cycling and minimising nutrient mining.
Soil organic matter is a very important factor in soil fertility. It is a reservoir of plant nutrients, has a high CEC, buffers soil pH, and chelates micronutrients. Organic matter exists in different forms in soil, ranging from living soil organisms to fresh, readily decomposed plant residues to humus that is very stable and resistant to further degradation. Living soil organisms include bacteria, fungi, actinomycetes, nematodes, earthworms, mites, and insects. They make up the soil food web, which carries out biological nutrient cycling. Plant roots are a sometimes forgotten part of the living soil biomass. Readily decomposed or active organic matter is the form of organic matter through which nutrients are actively recycled. Decomposition produces gums, polysaccharides (sugars), and other compounds that are the "glues" of water-stable soil aggregates necessary for good soil structure. Stable humus contributes to long-term nutrient supply and is the organic matter fraction with high CEC. Chelation is the ability of soluble organic compounds to form complexes with micronutrient metals that keep them in solution and available for uptake. In organic soils (peats and mucks), trace metal complexes with organic matter can reduce their availability.
The cycling of plant nutrients through soil organic matter supplies a significant portion of a growing crop's nutrient needs. Another aspect of this cyclical process is that organic matter not only contributes to soil fertility, but fertile soils contribute to the production of organic matter. One of the best ways to add organic matter to the soil is to maintain fertility and grow healthy crops that add large amounts of plant residue.
Foliar and root diseases, and nematodes. A healthy crop will best compete with weeds.