Plant Parasitic Nematodes in Rice-Wheat Based Cropping Systems in South Asia

Summary

Rice-wheat based cropping systems in South Asia are among the most highly evolved production systems in the world. The productivity growth of these systems in South Asia is declining due to several factors including the biotic stresses of plant parasitic nema-todes. This article reviews the research on rice and wheat nematodes in a cropping systems perspective and identifies nematodes that have wide host ranges and are greatly influenced by the crop rotations and sequences. These polyphagous nematodes can cause significant damage to rice and (or) wheat crops, either alone or in combination with other microorganisms. The research projects on pest management in the region lack inter-disciplinarity and it is important for nematologists to become integral members of interdisciplinary teams on improving the productivity and sustainability of the rice-wheat cropping systems.     

Weed Biology,Cropping Systems,and Weed Management

SUMMARY

Weeds pose a recurrent threat to agricultural productivity in both industrialized and developing countries. Weeds respond dynamically to all cropping practices, and therefore, the design and function of cropping systems plays a central role in the composition of weed communities. The unique and challenging nature of weed communities requires more integrated approaches to weed management than are currently being employed by most growers. Integrating weed management with cropping system design and application may be an effective approach to diversifying weed management systems. Each crop-weed system is a unique mix of genetics and biology and will respond dynamically to changes in management practices. Practices such as crop rotation, tillage, cover crops, and fertility management modify weed populations. The challenge is to integrate these and other practices with the best available control tactics to generate integrated management systems. Cropping system design provides an excellent framework for developing and applying integrated approaches to weed management because it allows for new and creative ways of meeting the challenge of managing weeds. Weed science must integrate the theories and application of weed management into cropping system design based on the unique characteristics of weed communities and the available weed management options.     

Cassava-Based Intercropping Systems on Sumatra Island in Indonesia: Productivity,Soil Erosion,and Rooting Zone

Abstract

In Gunung Batin, the southern end of Sumatra Island, Indonesia, cassava is widely cultivated on gently sloping areas for starch materials. The monoculture system and/or the intercropping system without legume plants commonly adopted in this region may tend to accelerate soil degradation. The objective of this study is to compare the productivity among several cassava cropping patterns to propose the most beneficial one in this region. A field experiment of five cropping patterns {cassava (Manihot esculenta Crantz) single-cropping, three cassava-based intercropping patterns, and a crop rotation} was conducted for three years. The cropping pattern that recorded the highest net income varied with the year. In 1997, the driest year of the past several decades, cassava single-cropping was the highest in income. The proposed intercropping system {cassava/(maize ? soybean ? cowpea)} was the highest in 1998, a year with moderate rainfall. In 1999, when severe insect damage occurred to legume crops, the farmers?conventional intercropping was the highest. In an average of the three years, the proposed intercropping pattern was same as cassava single-cropping, although cowpea cultivation as the dry season cropping was not possible in this region. The amount of soil erosion was relatively high in cassava monoculture in comparison with the other intercropping and crop-rotation systems. Cassava roots penetrated to only 0.5 m deep and extended 1 to 2 m in a horizontal direction depending on the planting density. These results lead to the conclusion that the proposed cassava cropping system would be the most beneficial in terms of economy and control of soil erosion.     

Challenges and opportunities for improving N use efficiency for rice production in sub-Saharan Africa

ABSTRACT

In sub-Saharan Africa (SSA), rice production from smallholder farms is challenged because of a lack of fertilizer inputs and nutrient-poor soils. Therefore, improving nutrient efficiency is particularly important for increasing both fertilizer use and rice yield. This review discusses how to improve the return from fertilizer input in terms of agronomic N use efficiency (AE_N), that is, the increase in grain yield per kg of applied N, for rice production in SSA. The AE_N values we summarized here revealed large spatial variations even within small areas and a certain gap between researcher-led trials and smallholder-managed farms. Experimental results suggest AE_N can be improved by addressing spatial variations in soil-related factors such as P, S, Zn, and Si deficiencies and Fe toxicity in both irrigated and rainfed production systems. In rainfed production systems, differences in small-scale topography are also important which affects AE_N through dynamic changes in hydrology and variations in the contents of soil organic carbon and clay. Although empirical evidence is further needed regarding the relationship between soil properties and responses to fertilizer inputs, recent agricultural advances have generated opportunities for integrating these micro-topographical and soil-related variables into field-specific fertilizer management. These opportunities include UAV (unmanned aerial vehicle) technology to capture microtopography at low cost, database on soil nutrient characteristics at high resolution and more numbers of fertilizer blending facilities across SSA, and interactive decision support tools by use of smartphones on site. Small-dose nursery fertilization can be also alternative approach for improving AE_N in adverse field conditions in SSA.

ABBREVIATIONS: AE_N: agronomic nitrogen use efficiency; FISP: farm input subsidy program; VCR: value cost ratio; SOC: soil organic carbon; SSA: sub-Saharan Africa; UAV: unmanned aerial vehicle     

Developing fertilizer recommendations for rice in Sub-Saharan Africa,achievements and opportunities

Improving agricultural productivity to keep pace with the fast-growing food demand is a huge challenge for sub-Saharan Africa (SSA). Fertilizer is a powerful productivity-enhancing input; nevertheless, farmers of SSA use only 5–9 kg ha^?1 of fertilizer, which is ten times lesser than Latin America and Asia (50 and 80 kg ha^?1, respectively). Rice (Oryza sativa) is one of the most important food crops of SSA, and its consumption is growing faster than any other commodity in Africa. Rice-based systems have high potential for improving food production through an efficient management of fertilizers. The biophysical environment, cropping systems and socio-economic status of farmers including market opportunities are the main factors for developing appropriate fertilizer recommendations. Many research efforts have been invested in different countries to develop fertilizer recommendation for rice. However, the diversity of rice ecologies, the type and the cost of fertilizers available on local market are the main constraints for development of blanket recommendations of fertilizer usually applied in many countries. Here, we make a reviews of the progress made on the development of fertilizer recommendations for rice-based systems in SSA. The utilization of the new concepts and decisions support tools for development of fertilizer recommendation and the main achievements and weakness are discussed. The opportunities offered by the new concepts, modeling and decision support tools are discussed in a regional strategic approach for better management of fertilizers in the diversified ecologies of rice-based systems.     

Shifts in Cropping System and Its Effect on Human Nutrition: Case Study from India

SUMMARY

More than twenty cropping systems are practiced in India. Rice-wheat and rice-rice are the major cropping systems practiced in an estimated 120 districts and 50 districts of the country, respectively. The rice-wheat cropping system (RWCS) of the Indo-Gangetic Plains (IGP) region of South Asia (Bangladesh, India, Nepal, and Pakistan) is the creation of the agricultural green revolution. Higher production of rice and wheat was necessary to meet the calorie needs of an increasing population in this region; as a result, the percent of malnutrition amongst children and adults decreased during the green revolution era. However, in recent years, there has been a reduction in both the rate of malnutrition decline and of the partial and total factor productivity of the RWCS in India. One of the many reasons for the decreased rate of malnutrition decline is micronutrient deficiency. Malnutrition amongst children and adults is a silent emergency in South Asia, including India. This review compares the food consumption habits, nutritional status, and cropping system practiced for different states of India to provide reasons for shifting the rice-wheat cropping system through crop diversification. Diversification of the RWCS will increase the supply of legumes and vegetables, help to diversify the diets consumed, and increase micronutrient intake. This approach is important for a largely vegetarian population of India, and is therefore, considered to be one of several important Food Systems strategy to address the silent emergency of malnutrition in the region.     

Expanding the Context of Weed Management

Abstract

Concerns about current weed control practices have increased the consideration of new weed management strategies. In recent times, weed control practices for major crops have been influenced greatly by the availability of selective herbicides. Herbicides are critical tools, but weed science must integrate more components to create weed management systems. Changes in weed management can be attained within the framework of existing cropping systems. However, for the longer term, new methods and approaches to weed management are needed. Weed scientists need to play a central role in the development of new cropping systems to make weed management an integral component of the system. This volume contains a series of review articles and original research that presents innovative approaches to weeds and weed management. It is our hope that these papers will stimulate discussion on a broader view of weeds and weed management.     

Annual forage legumes in dryland agricultural systems of the West Asia and North Africa Regions: research achievements and future perspective

Forage legumes are vitally important to animal production in the dryland farming systems of the Mediterranean region. Of the diverse forage‐legume species adapted to the Mediterranean climate, vetches, (Vicia spp.), chicklings (Lathyrus spp.), annual medics (Medicago spp), clovers (Trifolium spp.) and species of the Lupinus, Lotus, Onobrychis, Hedysarum and Ornithopus genera are considered to be the most agronomically important and economically valuable species for the region. Adoption of perennial self‐regenerating medic (Medicago spp.) has been limited because of technical difficulties, but annual vetch (Vicia spp.) has the greatest potential as a viable animal‐feed source and a rotation crop with cereals. Some forage legumes survive harsh conditions by their unique underground growth habit, for example, V. amphicarpa and Lathyrus ciliolatus. Efforts to improve forage legumes have been based on both management/cultural factors and breeding. Research based on several long‐term barley‐ and wheat‐based rotation trials has demonstrated the viability of forage legumes, especially vetch, in the region's improved farming system. An additional benefit to such legumes is the enhancement of soil quality, that is, soil fertility, soil organic matter and soil physical properties. Thus, the development of forage legumes is essential to agricultural sustainability in the Mediterranean region and in other dryland cereal‐growing areas of the world where grazing livestock is a dominant enterprise. To build upon the considerable research conducted on forages, intensified efforts are needed to develop locally adapted forage cultivars, to provide economic assessment of forages in cropping systems and to promote technology transfer at the farm and community level.     

A Framework for Economic Analysis of Cropping Systems: Profitability,Risk Management,and Resource Allocation

SUMMARY

A cropping system must be economically viable for it to be sustainable. This study focuses upon the economic components of profitability, risk management potential, and optimal resource allocation. Some of the primary aspects of economic analysis of cropping systems to a broad multidisciplinary audience of researchers, extension specialists, graduate students, and senior undergraduate students are addressed. Analytical economic tools are discussed including data requirements, advantages, and disadvantages of each method. A case study of a Henderson, Kentucky producer is presented as a primary example along with empirical applications from the literature. The importance of various types of economic analysis is demonstrated through the selection of different production decisions dependent on the level of economic analysis included.     

Effect of Introducing Nematode-Resistant Sweet Potato Cultivars on Crop Productivity and Nematode Density in Sweet Potato-Radish Double-Cropping Systems

Abstract

The root-knot nematode (RKN) is a significant pest in upland farming. We studied the effects of introducing nematode-resistant sweet potato cultivars on crop yield, crop quality, and RKN population dynamics in sweet potato-radish double-cropping systems. Three cropping systems with and without nematicide treatment (6 systems in total) were arranged for a 4-yr field experiment from 2003 to 2006. In two nematode-suppressive cropping systems, highly nematode-resistant J-red, (J) or Sunny red (S) and moderately nematode-resistant Kyushu No. 139 (K139) or Murasakimasari (M) sweet potato cultivars were cropped in alternate years beginning with the former and the latter, and in the non-nematode-suppressive cropping system, nematode-susceptible Kokei No. 14 (K14) and M were cropped in alternate years beginning with the former, from 2003 to 2005. In all cropping systems, K14 was cropped in 2006 to estimate the nematode-suppressive effect of the preceding 3-yr cropping. Introduction of J and S to the cropping system decreased the number of RKNs. In 2006, the extent of injury of K14 was decreased in nematode-suppressive cropping systems. The RKN population density, however, recovered during the cropping of K14 even after cropping of J or S or after nematicide treatment. This suggests that the effects of these measures last for only 1 yr. Nematode injury in radish decreased after nematicide treatment and after cropping of highly nematode-resistant J or S. These results indicate that the introduction of nematode-resistant sweet potato cultivars in cropping systems is effective for reduction of agrochemical use for sustainable agriculture.     

Cropping Systems and Integrated Pest Management: Examples from Selected Crops

SUMMARY

Cropping systems have been central to managing associated pests for centuries. This treatment focuses on the history, concepts, and the integration of available Integrated Pest Management (IPM) tools/strategies into cropping systems. Pest assessments/diagnoses, IPM-decision-making aids, and examples of pest management in selected crops/cropping systems (wheat, soybean, corn, cotton, potato, and strawberry) as well as emerging opportunities and challenges are discussed. The evolving philosophy of IPM and the recently renewed emphasis on ecologically based pest management address the fact that significant levels of predation and/or parasitism are desirable insofar as they promote diversity and sustainability of agroecosystems. Thus, cropping systems are beginning to focus on soil and crop health as well as specific IPM and production goals. Although extensive efforts have been directed toward modeling the many interactions between crops, associated pests and the environment, the general implementation of a systems approach to integrated crop and pest management remains to be accomplished.     

Implications of Elevated CO2-Induced Changes in Agroecosystem Productivity

SUMMARY

Since CO₂ is a primary input for crop growth, there is interest in how increasing atmospheric CO₂ will affect crop productivity and alter cropping system management. Effects of elevated CO₂ on grain and residue production will be influenced by crop selection. This field study evaluated soybean [C₃; Glycine max(L.) Merr.] and grain sorghum [C₄; Sorghum bicolor (L.) Moench.] cropping systems managed under conservation tillage practices and two atmospheric CO₂ concentrations (ambient and twice ambient) for three growing seasons. Elevated CO₂ increased soybean and sorghum yield by 53% and 17% increase, respectively; reductions in whole plant water use were also greater for soybean than sorghum. These findings suggest that increasing CO₂ could improve future food security, especially in soybean production systems. Elevated CO₂ increased aboveground residue production by > 35% for both crops; such shifts could complement conservation management by increasing soil surface cover, thereby reducing soil erosion. However, increased residue could negatively impact crop stand establishment and implement effectiveness during tillage operations. Elevated CO₂ increased total belowground dry weight for both crops; increased root proliferation may alter soil structural characteristics (e.g., due to increased number and extent of root channels) which could lead to increases in porosity, infiltration rates, and subsequent soil water storage. Nitrate leaching was reduced during the growing season (due to increased N capture by high CO₂-grown crops), and also during the fallow period (likely a result of altered decomposition patterns due to increased C:N ratios of the high CO₂-grown material). Enhanced crop growth (both above-and be-lowground) under elevated CO₂ suggests greater delivery of C to soil, more soil surface residue, and greater percent ground coverage which could reduce soil C losses, increase soil C storage, and help ameliorate the rise in atmospheric CO₂. Results from this study suggests that the biodegradability of crop residues and soil C storage may not only be affected by the environment they were produced in but may also be species dependent. To more fully elucidate the relationships between crop productivity, nutrient cycling, and decomposition of plant materials produced in elevated CO₂ environments, future studies must address species effects (including use of genetically modified crops) and must also consider other factors such as cover crops, crop rotations, soil series, tillage practices, weed management, and regional climatic differences.     

Cropping Systems in Eastern Europe: Past,Present, and Future

SUMMARY

The evolution of cropping systems in Eastern Europe has been a long and gradual process. The objective of this paper is to provide a comprehensive review of the cropping systems in Eastern Europe before World War II, the present cropping systems, and speculate on the future systems. Before World War II, the crop-long term fallow, the grass-crop, and the field rotation were the prominent cropping systems. Crop rotations were adopted in the 16th–17th century and various modifications of the ‘Norfolk’ and the ‘crop-grass’ rotation systems were used. Cash cropping, industrial cropping, and monoculture were extensively used after World War II. Major political, social, and economic changes took place in Eastern Europe after the dissolution of the Soviet Union. Nationalized land was returned to rightful owners. The new owners, however, lacked the skills and financial resources for intensive crop production and this has resulted in drastic reductions in crop yields. Integrated crop production seems to be the most viable option for the East European countries because organic or biological cropping is financially too demanding. Considerable efforts are being made to design new cropping systems which emphasize reductions in mineral fertilizers and pesticides, and conservation tillage. Eastern Europe may become important exporters of agricultural commodities by the year 2020.     

Socioeconomic and Agricultural Factors Associated with Mixed Cropping Systems in Small Farms of Southwestern Guatemala

SUMMARY

Many small farming communities in Latin America have modified their traditional cropping systems to incorporate non-traditional export crops (NTEC). The shift from subsistence to commercial agriculture is perceived by development agencies as an opportunity to alleviate poverty in rural areas. However, most small-scale farmers are not familiar with the production problems of NTEC, such as Bemisia tabaci and various geminiviruses transmitted by this whitefly species. In the absence of adequate technical assistance, due to drastic budgetary reductions in national agricultural research programs, farmers have relied on agrochemicals to protect their NTEC. This situation has led to considerable pesticide abuse and rejection of contaminated produce in international markets. This study analyzes some of the factors determining the adoption of NTEC and displacement of traditional food crops in southwestern Guatemala, and suggests possible measures to allow small farming communities to benefit from broad-based cropping systems that include both traditional and non-traditional food and cash crops.     

Soil Ecosystem Changes During the Transition to No-Till Cropping

Summary

Growers in the United States and worldwide are adopting no-tillage (no-till) cropping to reduce soil erosion, improve soil quality, increase water infiltration, and reduce number of passes with farm equipment over their fields. Soil erosion from dry farmed (i.e., non-irrigated) cropland in most regions of the United States exceeds the tolerable rate. An understanding of the changes in the soil ecosystem with changing tillage practices is needed to minimize the impact of agriculture on the environment and foster the use of sustainable agricultural practices. The soil biota is critical to the functioning of any agro-ecosystem, but studying the soil biota is difficult due to the diversity and the challenges associated with isolating and identifying these organisms. Soil disturbance or lack of disturbance can have a profound effect on biotic populations, processes and community structure. This contribution examines changes that occur in soil during the transition to no-till cropping, interrelations among organisms in the soil food web, and the relationships between organisms and their environment. As interest grows in sustainable cropping systems that mimic processes and soil organic matter turnover of native, undisturbed systems, it is imperative to understand how the transition to no-till affects an organism's niche, or functional role within the soil environment. Ecosystem investigations will enhance the understanding of changes that occur with the adoption of reduced tillage and no-till cropping systems so that these systems become increasingly viable.     

Host-parasite dynamics of Sorghum bicolor and Striga hermonthica – The influence of soil organic matter amendments of different C:N ratio

The effect of organic amendments on the interactions between Striga hermonthica and a sorghum host was studied in a field experiment during three cropping seasons, following a three-factorial design with (i) bare fallow versus continuous cropping, (ii) two Strigahermonthica infection levels and (iii) five organic matter levels, a single inorganic fertiliser treatment of 120 kg N ha⁻¹ and a control. The effects of two different cotton by-products and their mixtures on sorghum yield were well described by their N-mineralisation pattern. The impact of organic amendments in the sorghum production system was directly related to N-mineralisation in the three cropping seasons. There was an increasing negative effect of organic matter on S. hermonthica as the quality of the applied material increased. The emerged numbers of S. hermonthica were well described by N-release after one month, while S. hermonthica biomass and sorghum biomass were well described by N-release after three months. As a stand-alone measure, addition of low-quality organic matter is disadvantageous in cropping systems with high S. hermonthica seed densities, as it does not improve sorghum performance compared to no addition of organic matter, while S. hermonthica numbers increase. Implications for integrated soil fertility and S. hermonthica management under different infection levels of S. hermonthica are discussed.     

Disease risk perception and diversity of management strategies by farmers: The case of anthracnose caused by Colletotrichum gloeosporioides on water yams (Dioscorea alata) in Guadeloupe

Disease perception and adequate management practices are two essential issues faced by farmers, especially in the current context of climate change which may potentially increase disease risk. We investigated the diversity of water yam cropping systems in Guadeloupe through interviews, how producers and international yam research scientists perceived anthracnose, and how this perception correlated with farmers’ risk management strategies. We found that disease perception by farmers is very close to perception by international yam experts, as both have the same perception of the hierarchy of factors translating into disease. Three different yam production strategies coexist at a local scale, where agronomic practices and socio-economic profiles are distinct and consistent with attitude toward anthracnose risk management. Six factors were perceived as decreasing the disease: associated crop species; crop rotation; staking; weeding; crop monitoring and varietal admixture. Yam producers raising crops more intensively were risk prone, while others usually sought practices to manage disease appearance and spread. Both cumulative risk and past anthracnose epidemic experiences translated into heavier reliance on chemicals. These results have practical implications for designing best yam crop management systems and control of yam anthracnose.     

Determination of the potential land for securing double-rice cropping in the Cambodian Mekong Delta,based on a sub-area based modeling of flood inundation

Inundated areas of the Mekong Delta are the most important regions for agricultural production in both Cambodia and Vietnam. With population growth and increasing water demand in the dry season, effectively managing available water in the region is vital for crop production. This study is aimed at developing a sub-area based modeling of flood inundation model in order to analyze flood inundation processes in the Cambodian Mekong Delta as a basis for introducing semi-flood control for new cropping systems such as double-rice cropping. The simulated results of the flood inundation model from 2002 to 2003 were utilized for estimating land appearance in the dividing sub-area, and the potential of securing land for double-rice cropping was determined based on the period of land appearance and the cropping schedule. In order to realize the available water for double cropping, consideration of the effect of operating canal gates for controlling the early and receding inundation are crucially necessary. By considering the operation of control gates facilities, the potential land for securing double-rice cropping exceeded about 50 km² compared to the 34 km² of the actual land used for recession rice (about 30 and 20% of the total selected area, respectively). The study confirms that the sub-area based modeling of inundation model can be a helpful tool for water management in the Cambodia Mekong Delta.     

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.     

Forage Legumes for Sustainable Cropping Systems

SUMMARY

Perennial and annual forage legumes are important components of sustainable cropping systems. Forage legumes are a primary source of forage to supply protein and fiber for livestock rations. They can be grazed, or stored as hay or silage. They contribute biologically fixed N and sustain the soil by reducing erosion and increasing soil organic matter levels. Diversifying cropping systems by including legumes can also reduce weed, insect, and disease incidence. Potential new uses of legumes include phytoremediation of N contaminated sites and capturing N lost from cropping systems. Legumes also have potential use as a feedstock for renewable energy production. Legumes have traditionally been used in rotation with grain crops but more recently have been shown promise as winter cover crops, intercrops with grain crops, and as living mulches. In this review, we discuss traditional and new roles of forage legumes in sustainable cropping systems with examples primarily chosen from northern USA and Canada.