ABSTRACT
Soils have been and still are the primary medium for large-scale agricultural production upon which human civilizations have depended for sustenance and expansion. Over millennia, since the first human communities began settled agriculture, people have learned to manage and successfully cultivate their lands to produce the food required for nurturing modern societies and the development of their regions. Previously, communities were small and the demand on land and soil resources was low; hence, traditional agricultural practices could meet the needs of the population (Braidwood 1960; Piggot 1961). Following the industrial revolution in the 1800s, the world’s human population has grown tremendously, currently surpassing
6.1 Introduction .................................................................................................. 143 6.2 Impacts of Agricultural Intensification on the Environment ........................ 145 6.3 Social and Economic Aspects of Intensive Agriculture ............................... 149 6.4 Sustainable Agricultural Intensification ....................................................... 150
6.4.1 Integrated Nutrient Management ...................................................... 150 6.4.2 Crop Rotations and Cropping Patterns ............................................. 152 6.4.3 Biofertilization and Seed Inoculation ............................................... 152 6.4.4 Minimum and Zero Tillage .............................................................. 153 6.4.5 Biogas and Biochar ........................................................................... 155 6.4.6 Microirrigation and Water Management .......................................... 155 6.4.7 Other Holistic Management Approaches .......................................... 156
6.5 Future Priorities for Food Security and Environmental Protection ............. 157 6.6 Conclusions ................................................................................................... 159 References .............................................................................................................. 160
7 billion, with growth still rapid in the less developed countries of Asia, Africa, and the Middle East. Thus, while arable land has essentially reached the limits of expansion, pressures on the land resource base continue to increase with evergreater demands for food production. The need for producing higher amounts of food on the same amount of land has fuelled agricultural intensification. The Green Revolution of the post-World War II era enabled many advanced nations to dramatically increase crop yields and food production through the use of inorganic fertilizers and improved crop varieties. However, by the end of the 20th century, the impacts of intensified production systems, which relied heavily on man-made chemical fertilizers and pesticides, on the environment, as well as soil biophysical quality degradation, erosion, and fertility decline, could no longer be ignored (Thomas et al. 1956). As the nutritive requirements of a growing world population will only increase into the foreseeable future, sustainable agricultural intensification practices and technologies are indispensable. The development and adoption of such options will require concerted efforts on the parts of scientists, governments, and local farming communities merged through contextual knowledge systems. The application of integrated nutrient management has shown that optimum combinations of farmyard manure and inorganic fertilizers increased yields by 16%–35% in the mid-hills of Nepal. Similarly, a combination of compost and fertilizer gave significantly higher yields of wheat and potato crops over conventional farming. Combinations of different crops, such as pigeon pea and groundnut, have been shown to result in yield increases of maize of >100%, while leading to improved soil properties. Inoculation of seeds with Rhizobium strains have also been found to lead to yield increases of 40%–67% compared with non inoculated seeds for a variety of crops, such as soybean, lentils, black gram, groundnuts, and broad beans. Apart from crop and seed improvements, soil and water management options, such as conservation tillage, mulching, and microirrigation, are equally important in ensuring sustainable intensive production. Studies in the mid-hill region of the Himalaya have demonstrated that mulching and reduced tillage could lead to a reduction in soil and nutrient losses from upland farms by 46% to >100%, while increasing water retention and providing comparable crop yields. Thus, successful implementation of sustainable agricultural intensification to meet the growing global food demand will involve simultaneously addressing soil and land management, water use efficiency, crop and agrobiodiversity, and adequate policy and institutional support.
