Impact of Crop Production Inputs on Soil Health: A Review

External crop production inputs such as mineral fertilizers, organic amendments, microbial inoculants and pesticides are applied with the ultimate goal of maximizing productivity and economic returns, while side effects on soil health are often neglected. This study summarized the current understanding of how crop production inputs affect soil health (soil physical, chemical and biological properties). Mineral fertilizers have limited direct (such as soil physical property) effects but their application can enhance soil biological activity via increases in system productivity, crop residue return and soil organic matter. Another important indirect effect such as N fertilization is soil acidification, with considerable negative effects on soil health such as on amount, activity and diversity of organisms. Organic amendments such as manure, compost, biosolids and humic substances provide a direct source of C for soil organisms as well as an indirect C source via increased plant growth and plant residue returns. Non-target effects of microbial inoculants appear to be small and transient. Among the pesticides, herbicides have few significant effects on soil health, whereas negative effects of insecticides and fungicides are more common and their application warrants strict regulation. The sound management of crop production inputs must attempt to ensure both an enhanced and safeguarded environment; therefore, an Integrated Pest and Nutrient Management (IPNM) strategy that combines the use of chemical, organic crop production inputs together with cultural practices must be developed and evaluated as suggested by Integrated Pest and Nutrient Management Protocols (IPNMP).