Classical Farming Systems of China

Summary

During the long and dramatic history of agricultural civilization, a variety of technological methods have been developed and many valuable experiences accumulated on the farming practices. This review describes the progression of the agricultural development in ancient China. The practices and philosophies of classical farming in different historical periods are expounded and the characteristics of the classic farming practices in China are summarized. The paper also describes regeneration of the organic farming system, the development of the ecological and sustainable agricultural systems, the realistic significance of the knowledge of the classic farming methods such as application of organic manure and the systems of crop rotation and intercropping.     

Limited Increase of Agricultural Soil Carbon and Nitrogen Stocks Due to Increased Atmospheric CO2 Concentrations

SUMMARY

Increased atmospheric concentrations of CO₂ may lead to increases in agricultural soil carbon and nitrogen storage, but the impact is likely to be small and is uncertain due to limitations in other resources (e.g., nutrients, water) and interactions with climatic changes. Since only a small percentage of carbon added to the soil becomes stabilised, the impact of CO₂ fertilisation of crops is considered to be very small compared to deliberate efforts to increase soil carbon by improved agricultural management. Even if agricultural soil carbon stocks are increased, carbon credits cannot be claimed under the Kyoto Protocol since the increases are not directly human-induced, a condition which must be met in order for any carbon sink to be included in emission reduction targets.     

Biological Practices and Soil Conservation in Southern China

Summary

Southern China has abundant natural resources and is a major region of agricultural production. However, soil erosion is increasingly threatening the agricultural productivity of this region. Increases in soil erosion are caused by improper land use practices with soils of high rainfall erosivity. Much of the area prone to accelerated erosion was previously forested and subsequently logged four times since the 1920s. This paper discusses the effects of biological control practices on soil erosion according to erosion types, soil properties, and terrain.     

Crop Technology Introduction in Semiarid West Africa: Performance and Future Strategy

SUMMARY

The periodic food crises in agricultural production in semiarid sub-Saharan Africa have been the main public view of the subcontinent since the media perpetuates a Gloom and Doom perception. Actually the agricultural systems of sub-Saharan Africa have made some impressive achievements and there is potential to make more impact even in the more difficult regions where the poor are concentrated. In this paper the focus is on the successes, a strategy for introduction of new technologies in semiarid regions of West Africa, and supportive policy. More rapid technological change, with supportive policy, would have a substantial effect on rural poverty.     

The causes of soil alkalinization in the Songnen Plain of Northeast China

The causes of soil alkalinization in the Songnen Plain of Northeast China were mainly analyzed from two aspects, natural and anthropogenic. Natural factors of alkalinization are parent materials, topographic positions, freeze-thaw action, wind conveyance, water properties and semi-arid/sub-humid climate. Some of them were always being neglected, such as freeze-thaw action and wind conveyance. Anthropogenic causes are mainly population pressure, overgrazing and improper agricultural and economic policies. In recent decades, overgrazing played a main role in secondary soil alkalinization, which led to the decline of Leymus chinensis grasslands. Now, the alkalinization is very severe, and more than 3.2 × 10⁶ ha area has been affected by salt, which becomes one of the three largest sodic–saline areas in the world.     

Potato growth with and without plastic mulch in two typical regions of Northern China

Plastic film mulching is an important agricultural practice to save water and improve crop productivity in Northern China. Three field experiments were conducted to examine the effect of plastic mulch on soil temperature, potato (Solanum tuberosum L.) growth and evapotranspiration under drip irrigation in two typical regions of Northern China in 2001 and 2006. Results suggest that daily mean soil temperature under mulch was 2–9 °C higher than without mulch, especially during the early growth. Potato growth was restrained under mulching conditions in the North China Plain mainly due to the higher air temperature in this region and thus the higher soil temperature. The negative effects of mulching included a lower emergence and fewer marketable tubers per plant. Evapotranspiration and potato tuber yield were both reduced by mulch, especially in the North China Plain. In northwest China, mulch favorably increased the weight of jumbo tubers (W ≥ 300 g) per plant. Mulching duration had little effect on potato evapotranspiration in northwest China. However, both tuber yield and water use efficiency (WUE) decreased with increases in mulch duration, which suggests the plastic mulch should be removed early.     

Managing Soil Fertility Decline

Summary

Soil fertility is defined in terms of the ability of the soil to maximize plant productivity, often within economic constraints. A decline in natural soil fertility seems to have occurred over all civilizations. Overgrazing and deforestation are the two most important factors affecting global soil degradation. Nutrient losses from agricultural systems are broadly divided into losses through volatilization, losses from leaching, losses due to product removal, losses to non-labile soil pools and losses from various forms of erosion. Rapid declines in soil fertility are associated with large demands for food due to expanding population, nutrient mining of agricultural areas with concomitant shifts of produce to cities, and intensification of agricultural activities without proper regard for long-term maintenance of fertility by application of fertilizers, recycling of organic wastes, liming to combat acidification, fallowing, rotations and prevention of large scale soil erosion. Agricultural policy has often encouraged soil fertility decline and soil degradation. In the future, agricultural scientists must have major inputs into the development and implementation of policy.     

中国小麦的起源、传播及进化

小麦是由西亚引入我国的主要粮食作物之一,是古丝绸之路物质和文化交流的产物。研究认为,大约3800年前的新石器时代晚期至青铜器时代早期,小麦被引入河西走廊地区,作为春麦种植,逐步引种到祁连山以南地区,到达海东和洮河流域,之后进入关中平原;然后,进化为冬小麦,以适应当地的种植制度。西汉时期,由于朝廷的重视和推广,小麦开始在黄河及淮河流域种植。由于小麦可秋播夏熟,产量稳定,具有救荒救灾的作用,使小麦在中国的种植区域持续扩大。近百年来由于作物遗传育种和栽培技术水平的提高,目前小麦产量已达到每公顷10 500 kg以上。小麦在中国的传播和进化,对中国的农业生产结构以及人们的饮食结构和饮食文化产生了深远的影响。     

Association of Pythium and Phytophthora with Pre-emergence Seedling Damping-off of Soybean Grown in a FieldConverted from a Paddy Field in Japan

Abstract

In Japan, soybean is usually cultivated in fields that have been converted from rice paddies, and poor seedling establishment due to pre-emergence seedling damping-off is often observed during the rainy season. In this study, the factors that cause the damping-off in flooded soil were investigated under high soil moisture conditions in a greenhouse and in agricultural fields. In sterilized soil sampled from a soybean field, seedlings emerged well under 48-hr flooded conditions. In unsterilized soil, soybean seeds treated with the fungicide, mancozeb+metalaxyl exhibited much higher emergence rates even under 48-hr flooded conditions than the seeds treated with oxytetracycline +streptomycin, benomyl, or flutolanil. Pythium, Phytophthora, Mucorales, Trichoderma, Geotrichum-like microorganisms, and some fungi producing conidia in a false head, were isolated from decayed seedlings. Of the isolated microorganisms, oomycete microorganisms, Pythium helicoides, other Pythium sp., and Phytophthora sp. were pathogenic to soybeans under flooded conditions. As the length of the flooding period increased, pre-emergence seedling rot also increased. However, the pathogenic oomycetes rarely caused pre-emergence seedling rot under conditions without flooding. Furthermore, under flooded conditions, the damage caused by these pathogens was reduced by treating the seeds with mancozeb+metalaxyl. These results indicate that oomycete microorganisms are involved in pre-emergence seedling damping-off under flooded soil conditions.     

Nutrient Deficiency in the Rice-Stylo (Stylosanthes guianensis) Relay-Intercropping System in Rainfed Lowland Rice Ecosystem in Northeast Thailand

Abstract

The rice-stylo (Stylosanthes guianensis) relay-intercropping system in paddy fields has previously been shown to increase agricultural productivity in Northeast Thailand, but successive relay-intercropping conducted without irrigation and fertilization during the stylo cropping has resulted in reduced production of stylo. The aim of this study was to determine the effect of nutrient deficiency on the stylo production. The experiment was conducted using pots to control fertilization accurately. The results showed that, after three successive relay-intercroppings, the soil was severely deficient in sulfur, phosphorus, and molybdenum. Sulfate application to the soil after the successive relay-intercroppings was suggested to improve stylo production. We recommend the use of a rain-fed shallow, favorable subecosystem as a field for stylo production in relay-intercropping and the stylo production with a cycle of several years.     

Production and Application of Organic Materials as Fertilizers

Summary

The rapid social and economic changes in recent years have enhanced the development and availability of a large number of industrial and agricultural products. Such activities, in turn, have greatly increased the amounts and volumes of organic wastes and residues. It is important for Chinese scientists to know the types and amounts of waste materials produced each year and, if suitable for land application, utilize them as soil conditioners and fertilizers. Such information with respect to China is reviewed and discussed in this paper.     

Impact of Global Change on Biological Processes in Soil

SUMMARY

The Earth is undergoing rapid environmental changes due to human activities. Three components of the ongoing global change, elevated atmospheric CO₂, N deposition, and global warming, may significantly impact soil biota directly through modifying the physical and chemical environment, and indirectly through altering aboveground plant growth and community composition. The biomass, community structure, and activities of microbes and animals in soil as well as their interactions will likely be affected, leading to changes in ecological processes and functions. Biological processes that may be modified by global change include organic matter decomposition, N mineralization, food web interaction, and biotic N fixation. Lack of the complexity in agroecosystems may amplify the effects of global change on many biological processes in agricultural soils. However, minimizing human disturbance and thus increasing the complexity of agroecosystems may enhance the potential of C sequestration in agricultural soils and the stability of belowground systems, thereby contributing to ecological sustainability.     

Allelopathic Influence of Decomposing Wheat Residues in Agroecosystems

Summary

The concept that some crop plants have allelopathic effects is receiving greater attention as a potential mean that can be exploited in various ways for controlling agricultural pests. Wheat residues have been reported to inhibit growth of certain weeds, crops that follow wheat crop in crop rotation, soil nitrification and biological nitrogen fixation. Thus, crop production can be enhanced by avoiding the inhibitory effects or by exploiting favorable interactions. The present article presents an overview of research on the allelopathic influence of wheat residues in agroecosystems.     

The Potential Effect of Climate Change and Elevated Air Carbon Dioxide on Agricultural Crop Production in Central and Southeastern Europe

SUMMARY

The vulnerability and adaptation of major agricultural crops to different soils in Austria and Bulgaria under a changing climate and elevated air CO₂ were investigated. Several incremental and transient GCM climate change scenarios were created and applied. Warming will decrease the crop-growing duration of the selected crops in the regions of interest. All GCM scenarios, including the climate change effect only, projected reductions in grain yield of winter wheat and spring barley, caused by a shorter crop-growing period. However, when the direct effect of an increased CO₂ level was assumed, most GCM climate change scenarios projected an increase in wheat and barley yield and especially in soybean yield. An increased level of CO₂ alone had no significant impact on the simulated maize yield reductions under climate change.     

Seed development and seed shedding in North Italian ecotypes of Lolium multiflorum

Seed development and seed shedding were studied in seven populations of Lolium multiflorum. Five of these populations were from the North Italian Plains, two from the Piedmont area and three from the Lombardy region. The remaining populations were Delecta, a variety derived from ecotypes from the Lombardy Plain, and RvP Lemtal. Seed shedding was greatest in the three ecotypes from the Lombardy Plain and lowest in RvP Lemtal. The two ecotypes from the Piedmont Plain, and Delecta, gave intermediate values. Moisture loss during ripening was greatest in the Lombardy ecotypes but there were no differences in the time taken to reach maximum 1000-seed weight. Germination values had reached a maximum 27 d after anthesis in all populations. It is suggested that the North Italian ecotypes, or varieties derived from them, should be harvested by direct combining at a moisture concentration of 450 g kg^-1 (≡45%) to obtain the maximum weight of germinable seed.     

The Role of Nitrogen Fixation in Crop Production

Summary

Biological nitrogen fixation is an important process for agricultural productivity in many cropping systems because of direct inputs of atmospheric nitrogen, and rotational effects such as disease control. Advances in molecular biology techniques provide new opportunities to understand the ecology of root nodule bacteria and may improve the selection of elite strains for inoculation. An understanding of the genetic basis of nodulation in grain and pasture legumes may improve inoculation technologies. Temperate and tropical pastures may be improved through effective inoculation, removal of nutritional constraints, and use of alternate legume species. Increases in nitrogen fixation in crop legumes may result from addressing problems in the legume host, the microsymbiont and the environment.     

小麦籽粒营养品质及品质产量的边际效应

为阐明小麦籽粒营养品质及品质产量的边际效应,以黄淮麦区不同品质类型的4个小麦品种为材料,于2010-2012年度对不同麦行籽粒蛋白质、淀粉、可溶性糖含量等营养品质指标和品质产量进行了系统研究。结果表明,不同行次间籽粒蛋白质含量和可溶性糖含量差异达显著水平,其中边1行、边2行、边3行和边4行的籽粒蛋白质含量分别为136.79、131.02、129.50、126.58 mg·g^-1,可溶性糖含量分别为113.08、91.61、93.55、87.91 mg·g^-1;不同行次间籽粒淀粉含量差异达显著水平;不同行次间籽粒蛋白质产量和淀粉产量的差异达显著水平,其中,边1行、边2行、边3行和边4行的籽粒蛋白质产量和淀粉产量分别为1 543.3、995.7、987.1、930.9 kg·hm^-2和6 480.6、4 284.9、4 383.6、4 126.3 kg·hm^-2,边际效应显著。本研究表明,小麦营养品质和品质产量具有显著的边际效应,生产中可通过改革种植方式、合理选用品种等加以充分利用。     

An Agroecological Basis for Designing Diversified Cropping Systems in the Tropics

Summary

Small scale diversified systems which rely mostly on local resources and complex crop arrangements, are reasonably productive and stable, exhibiting a high return per unit of labor and energy. In many ways complex polycultures and agroforestry systems used by small tropical farmers mimic the structure and function of natural communities therefore acquiring many features typical of such communities, such as tight nutrient cycling, resistance to pest invasion, vertical structure, and high levels of biodiversity.

An agroecological approach to improve tropical small farming systems must ensure that promoted systems and technologies are suited to the specific environmental and socio-economic conditions of small farmers, without increasing risk or dependence on external inputs. Rather, agroecological development projects should incorporate elements of traditional agricultural knowledge and modern agricultural science, featuring resource-conserving yet highly productive systems such as polycultures, agroforestry, and the integration of crops and livestock.

It is ecologically futile to promote mechanized monocultures in areas of overwhelming biotic intricacy where pests flourish year-round and nutrient leaching is a major constraint. Here, it pays to imitate natural cycles rather than struggle to impose simplistic ecosystems that are not inherently complex. For this reason, many researchers think that successional ecosystems can be particularly appropriate templates for the design of sustainable tropical agroecosystems.     

A Comparison of Intensive Rice Production in Japan and Wheat Production in Europe: The Contribution of Minimum Tillage to Sustainability

Abstract

This review paper examines some of the issues concerned with sustainable production of two major cereal crops – wheat and rice. We compare the perceived threats to sustainability in intensive production of rice in Japan and wheat in Europe, and evaluate the contrasting experiences with minimum tillage as a possible technique for greater sustainability. The contrasts which are presented reveal how perceptions about environmental threats vary widely, and how social and economic factors, as well as purely environmental issues, greatly influence the conclusions reached about sustainability. Before drawing these comparisons, however, we present a brief outline of the two crop systems as practised in Japan and Europe, and describe the experiences in both regions of using minimum tillage.

The comparison presented has shown that there are no simple solutions to the problem of sustainability. Management techniques which work well in one situation, for example minimum tillage for wheat, may be inappropriate for another crop. Furthermore, the search for sustainability is strongly constrained by social and economic circumstances which ultimately determine which management options are viable. Indeed, although awareness of the need for more sustainable agricultural practices is growing, both in Japan and Europe, short-term economic considerations continue to be the dominant influence affecting agricultural practice in both regions.     

Brazilian Agriculture: The Transition to Sustainability

SUMMARY

Brazil has a total area of 850 million ha, of which 90% is within the tropics. Historically, the system of exploitation of the land for agriculture and forestry was based on land clearing, cultivation for some years and then moving on to new areas. This process often left degraded areas behind, especially in the mountainous areas of the country. With modern agricultural technology, crops can be successfully grown in virtually any region of the country. The current challenge for Brazil is to feed its population and provide agricultural surpluses for the growing export markets, while preserving its rich and biologically-diverse native vegetation which still covers almost half of the country. The objective of this review is to trace the history of agricultural activity in this country, and to assess the sustainability of the cropping and pasture systems which today occupy the largest areas. At present approximately 50 million ha are under annual and perennial crops, while almost twice this area is under pastures. These pastures, predominately Brachiaria spp., are mostly in a degraded state due to lack of fertilization and over grazing. The various options available to recover these pastures or convert these areas for sustainable cropping are explained. In recent years, increasing proportions of soybean, wheat, and corn are produced under zero tillage which favors the conservation of soil organic matter. This not only radically reduces the risk of erosion but also increases the capacity of the soils to retain nutrients and water. Small holders who represent a considerable fraction of Brazil's food crop production, generally do not have access to fertilizers or other agricultural chemicals. They obtain very low yields and their farming practices exhaust the soil of nutrients. The Brazilian sugarcane industry is the largest in the world and recent changes in the management of this crop and its impact upon sustainability issues are also discussed. Brazil also has vast areas of degraded pastures and abandoned hillsides that can be used for agricultural expansion. This would prevent further destruction of native vegetation and its accompanying biological diversity for agriculture.