Green Revolution and Organic Farming
Green Revolution technology has been criticized for its deficiencies (Swaminathan 2006; Robertson and Swinton 2005). Economists stress that, because marketpurchased inputs are needed for production, only resource-rich farmers can take advantage of high-yielding crops. Environmentalists emphasize that the excessive use of fertilizers and pesticides, as well as the monoculture of a few crop cultivars, will create serious environmental problems, including the breakdown of resistance in plants and the degradation of soil fertility by disturbing the stoichiometry.
Organic farming is probably an alternative to modern intensive farming. Organic farming uses organic fertilizers to sustain fertility of soil and reduce chemicals to control pests and weeds. Badgley et al. (2007) argued that the global population can be supported by organic farming. The principal objection to the proposition that organic agriculture can contribute significantly to the global food supply is the fact that organic yields are typically lower than conventional yields (Seufert et al. 2012), necessitating more land to produce the same amount of food as conventional farms. However, when using best organic management practices yields are closer to conventional yields (−13 %). Organic agriculture also performs better under certain conditions—for example, organic legumes or perennials, on weak-acidic to weakalkaline soils, in rainfed conditions, achieve yields that are only 5 % lower than conventional yields (Seufert et al. 2012).
Biodiversity, Ecological Functioning, and Ecosystem Services
Recent experimental advancements in biodiversity and ecological functioning were mainly obtained in laboratory microcosms, benthos communities (Cardinale et al. 2012), and model grassland studies (Tilman et al. 2001). Varying component species numbers from one (monoculture) to 16 species (average species richness in natural grasslands in Minnesota), Tilman et al. (2001) showed that plant production was higher with increasing species richness. Increase in species richness heightens the chances of involving functional species (sampling effect; c.a. legumes that fix atmospheric nitrogen thus increase nitrogen resources in soil) and also enhances functional diversity (niche complementarity effect).
Niche complementarity explains the decrease in nitrate nitrogen concentration in soil with increasing plant species richness. The greater the species richness, the more efficiently the plant uptakes nitrogen by root due to complement root depth and morphology compared to monoculture soil.
The longer the experiment continues, the higher the stability of primary production (Tilman et al. 2006b). This is explained by the portfolio effect of different species that respond differently to environmental conditions such as drought, high and low temperature, etc. The ratio of predators to prey in aboveground communities tends to increase with plant species richness (Haddad et al. 2011). Therefore this mechanism also contributes to the stability of primary production. Tilman et al. (2006a) concluded that natural short grass prairie is the most productive for supplying biomass for energy use under no-fertilization conditions.
Organic farming avoids utilization of synthetic fertilizers, chemical pesticides, and herbicides. The recent ecological studies on biodiversity suggest that increasing plant species richness leads to efficient nutrient use, fewer outbreaks of pests and pathogens, and stable yields for a certain period. Some organic farming techniques, such as intercropping, use of companion plants, patchy land use, and also agroforestry all increase plant biodiversity compared to monoculture.
