This chapter considers the land use issues raised by nitrate in the environment under the following sections: Sustainability; The principle of minimum entropy production; Sustainable agriculture; ...Organic farming; No-till agriculture; Reforming farming; Farming and food: the Policy Commission; and Implications of Bertilsson's approach.
Carbon terrestrial sinks are often seen as a low-cost alternative to fuel switching and reduced fossil fuel use for lowering atmospheric CO2. To determine whether this is true for agriculture, one ...meta-regression analysis (52 studies, 536 observations) examines the costs of switching from conventional tillage to no-till, while another (51 studies, 374 observations) compares carbon accumulation under the two practices. Costs per ton of carbon uptake are determined by combining the two results. The viability of agricultural carbon sinks is found to vary by region and crop, with no-till representing a low-cost option in some regions (costs of less than $10/tC), but a high-cost option in others (costs of $100-$400/tC). A particularly important finding is that no-till cultivation may store no carbon at all if measurements are taken at sufficient depth. In some circumstances no-till cultivation may yield a “triple dividend” of carbon storage, increased returns and reduced soil erosion, but in many others creating carbon offset credits in agricultural soils is not cost effective because reduced tillage practices store little or no carbon.
A return to old species cultivated in the past, especially those with high health-promoting and nutritional values, such as spelt (Triticum aestivum ssp. spelta) is being increasingly observed. In ...addition, due to the increasing use of soil protective cultivation systems in recent years, such as no-tillage cultivation or direct sowing, the aim of the study was to assess the mycobiota of spelt rhizosphere and root-free soil, determine the ratio of potentially pathogenic to antagonistic fungi and assess the impact of cultivation systems on the frequency and biodiversity of fungi. The frequency and species composition were examined in 3-years cultivation of two spelt cultivars. The total number of rhizosphere fungi was significantly higher in the no-tillage system and under the spelt cultivar Franckenkorn compared to the tillage system and the cultivar Badengold. The species richness of the analyzed experimental variants was similar. The dominant group of fungi was the order Hypocreales (Ascomycota). Ninety-five percent of the fungal population from the rhizosphere and 88% of fungi from root-free soil belonged to rare (1–5%) or sporadic species (<1%). Taxa with higher frequency (>5%) in the rhizosphere included: Clonostachys, Gibellulopsis, Rhizopus and Sarocladium, Mortierella, Mucor, Penicillium, Sarocladium and Trichoderma. The cultivation system and plant cultivar affected the occurrence and distribution of fungal populations in the rhizosphere and root-free soil. The similarity of species composition of fungal communities in the rhizosphere and root-free soil was low, while taking into account species frequency, their diversity was high. The ratio of antagonistic to potentially phytopathogenic fungi of spelt rhizosphere deteriorated in the 2nd and 3rd year of wheat cultivation.
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•Cultivation and spelt cultivar affected the taxonomic and spatial structure of fungi.•No-tillage cultivation was more beneficial for rhizosphere fungi of spelt.•Spelt cultivation in succession weakens the antagonistic potential of rhizosphere fungi.
The basic taxonomy of nematodes and resources for nematode identification in Brazil are briefly discussed. Their communities were assessed based on: (i) abundance (population density and relative ...abundance); (ii) diversity (generic richness, Shannon-Weaver's and Simpson's diversity indices and evenness of both indices, trophic diversity and dominance); (iii) trophic habits (plant parasites, bacterial and fungal feeders, omnivores and predators); (iv) soil disturbance; (v) soil decomposition pathway (ratios of fungivores/bacterivores) and of (fungivores+bacteriovores)/plant parasites; (vi) index of similarity; and (vii) correspondence analysis. Nematode community structure is discussed in two areas, the Amazonian tropical and humid region with sampling sites in two western states, Rondônia and Acre, and the tropical savannah (cerrado) region in the 3 central states of Goiás, Minas Gerais and Districto Federal. In the Amazon, community structure for periodically flooded and non-flooded ecosystems (in four sites near Manaus), and for five land use types in the western states (forest, annual crops, pasture, fallow and agroforestry) are considered. In the savannah region, nematode communities are discussed with reference to native and cultured systems, managed soybean plantations, temporal and spatial samplings and edaphic factors. It was shown that nematode diversity is closely related to vegetation diversity (both in natural and in agricultural systems), with, somewhat counterintuitively, plant parasites the most important functional group in native vegetation versus bacterial feeders in agricultural systems. Nematode abundance is generally greater in agricultural systems.
This chapter describes the innovation system that generated zero tillage (ZT) technology in Argentina, based on a review of relevant literature and semistructured interviews with 21 key informants in ...Argentina and 43 informants in Brazil, Paraguay, Mexico, and the UK. The chapter reviews the concept of a national innovation system and sketches a new framework for the analysis of research systems. It examines ZT from an economic perspective and gives a brief history of ZT in Argentina. It also describes the organization of the innovation system centred in ZT, in which public and private agents interact through formal and informal channels, as well as the failures of the system.
The rice-wheat cropping system is found on 13.5 million ha in south Asia and is one of the most important cropping patterns for food self-security in the region. This system is found in the fertile, ...hot semi-arid to hot subhumid regions of the Indus and Gangetic alluvial plains of Bangladesh, India, Nepal and Pakistan. Irrigation is commonly used to stabilize the productivity of this system, using canal and tube-well water. Area and yield growth have been responsible for continued production growth for these cereals over the past 30 years and have matched the population growth and demand for food. This growth over the past 30 years was based on key inputs, such as variety, fertilizer and irrigation, with most of the investment coming from the public sector. Future growth required to meet population growth will be close to 2.5% year and must come from yield rather than from area growth, since the latter will decline as urbanization and industries spread to prime agricultural land. Competition for water will be a major challenge for agriculture and it is imperative that this scarce resource is used efficiently. This chapter describes various resource-conserving technologies that are being promoted by the rice-wheat consortium (one of seven Consultative Group on International Agricultural Research ecoregional initiatives) to attain the goal of raising productivity in the region and meeting food-security needs while, at the same time, efficiently using natural resources, including water, providing environmental benefits, improving the rural livelihoods of farmers and helping to alleviate poverty. This technology of the post-green revolution will depend on farmer adoption and investment. Increasing and improving stakeholder participation in experimentation and fine-tuning of the technology will be a key to success.
Nitrogen (N) is an essential element required for the growth and development of all plants. On a global scale, N is agriculture's most widely used fertilizer nutrient. Studies have shown that crops ...use only 50% of the applied N effectively, while the rest is lost through various pathways to the surrounding environment. Furthermore, lost N negatively impacts the farmer's return on investment and pollutes the water, soil, and air. Therefore, enhancing nitrogen use efficiency (NUE) is critical in crop improvement programs and agronomic management systems. The major processes responsible for low N use are the volatilization, surface runoff, leaching, and denitrification of N. Improving NUE through agronomic management practices and high-throughput technologies would reduce the need for intensive N application and minimize the negative impact of N on the environment. The harmonization of agronomic, genetic, and biotechnological tools will improve the efficiency of N assimilation in crops and align agricultural systems with global needs to protect environmental functions and resources. Therefore, this review summarizes the literature on nitrogen loss, factors affecting NUE, and agronomic and genetic approaches for improving NUE in various crops and proposes a pathway to bring together agronomic and environmental needs.
Crop residue retention and minimum tillage (including no–tillage, NT, and reduced tillage, RT) are common conservation tillage practices that have been extensively applied for improving soil health ...and reducing the negative environmental impact caused by intensive farming. However, the effects of minimum tillage, coupled with crop residue retention (including no–tillage plus residue retention, NTR, and reduced tillage plus residue retention, RTR), on soil organic carbon (SOC) stock have not been systematically analyzed. Using a dataset consisting of 1928 pairs of data points from 243 studies, we conducted a global meta–analysis to evaluate the effects of crop residue retention and minimum tillage on SOC stock in the 0–30 cm soil and how these effects varied with soil (soil sampling depth and texture), environmental (climate) and crop management conditions (cropping intensity), as well as treatment duration. We found that regardless of the climatic condition, crop management, or residue retention, minimum tillage alone increased the overall mean SOC stock. Specifically, NT and RT increased SOC stock by 11 and 6%, respectively, in comparison to conventional tillage (CT). Compared with CT, NTR and RTR increased SOC stock by 13 and 12%, respectively. The above effects were greater in the topsoil (62% of data points from the 0–15 cm depth) than in the subsoil (38% of data points from the 15–30 cm depth). Moreover, residue retention enhanced the resistance of SOC turnover to agricultural and environmental factors; mean annual temperature (coefficient = 0.15), soil pH (0.14), and experimental duration (0.08) were critical for increasing SOC stock with minimum tillage alone, while the response ratio of SOC stock under coupled residue retention and minimum tillage was insensitive to changes in those factors. Additionally, double cropping generally increased SOC stock cross all conservation tillage practices compared to multiple cropping. Therefore, we conclude that minimum tillage coupled with residue retention in a double-cropping system is the most promising management system for increasing SOC stocks in the 0–30 cm soil in croplands Our finding can inform sustainable soil management practices aimed at increasing resistance of SOC in croplands to climate change and soils degradation induced by intensive agriculture.
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•No-tillage (NT, 11%) increased more C than reduced tillage (RT, 6%) over tillage (CT).•Compared with CT, NTS (13%) and RTS (12%) further increased C stock.•Residue retention enhanced the resistance of SOC to agricultural/environmental factors.•MAP, soil pH, and experimental duration greatly affected SOC stock with NT or RT.
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