Protecting the heritage of rice biodiversity

The development of improved rice varieties depends upon access to the genetic resources of rice. These are represented by the thousands of locally adapted varieties that farmers have grown for generations, and over 20 wild rice species native to Asia, Africa, and Latin America. Rice genetic resources are threatened with extinction in farming systems when farmers adopt improved varieties, and the wild species may be lost through destruction of their habitats.IRRI has been at the forefront of international efforts for three decades to collect and conserve the biodiversity of rice. More than 80,000 samples of cultivated and wild rices are conservedex situ in the genebank at IRRI.In situ conservation of rice genetic resources is likely to become an important complementary strategy in the future.Through utilization of rice germplasm, resistances to pests and diseases have been incorporated into improved varieties. These are shared worldwide through the International Network for Genetic Evaluation of Rice (INGER). The impact of biotechnology and intellectual property rights on germplasm conservation is discussed.     

Ecological benefits of Anystis baccarum in an orchard ecosystem and the need for its conservation

Integrated pest management programs are very important in the control of invertebrate pests within apple orchards. Many current integrated pest management strategies concentrate on specialist predatory species. However, generalist beneficial insects, such as several mite species, must also be fully researched for their potential in controlling pests. Previous research has shown that the generalist predatory mite Anystis baccarum (Linnaeus) can offer much potential in controlling invertebrate pests within Northern Irish apple orchards. However, apple growers have been mis-identifying this beneficial species as the economic pest European fruit tree red spider mite, Panonychus ulmi (Koch). As a result, unnecessary pesticide applications have been applied against what has now been confirmed as a beneficial species. To aid apple growers in the identification of A. baccarum, identification cards were produced. Positive uptake of the cards by many apple growers has resulted in correct identification of A. baccarum from P. ulmi, and therefore, a reduction in chemical pesticide applications. The benefits of A. baccarum within orchard ecosystems is discussed.     

Extension of nitrogen fixation to rice — Necessity and possibilities

Nitrogen supply is critical in attaining yield potential. Achieving the 50% higher yields that will be needed by 2025 will require at least double the 10 m tons of N fertilizer that is currently used each year for rice production. But manufacturing of fertilizer N is dependent on fast depleting non-renewable energy resources. It is in this context that biological nitrogen-fixation-derived N assumes importance in the lowland soils that provide about 86% of the world's rice.Among the conventional systems, green-manure legumes have high N supply potential. But due to associated additional costs such as labour and land opportunity, they do not form an attractive option for farmers. Rice associative N₂ fixation (ANF) although has low activities, any increase will be attractive to farmers as it does not require changes in existing cropping systems, and soil and water management practices. Recently, we identified quantitative trait loci underlying ANF in rice (Wu, P.; Zhang, G.; Ladha, J. K.; McCouch, S. and Huang, N.: Restriction fragment length polymorphic markers associated with rice varietal ability to stimulate nitrogen fixation in rhizosphere. Rice Genetic Newsletter 1994 — submitted). The presence of this trait in rice provides an evidence of the occurrence of genetic factors which regulate interaction of rice with diazotrophs in rhizosphere. However, the ANF trait governing the loose diazotroph-rice association appears to have limited potential for enhancing yield. To achieve higher yields, intimate association similar to sugar cane-Acetobacter/legume-rhizobia symbioses will have to be developed in rice. In this paper, we discuss the strategies for transferring nitrogen-fixing capacity to rice.     

气候变化下长江中下游水稻灌溉需水量时空变化特征

选择长江中下游单季中稻为研究对象,结合45个气象站1961~2010年逐日气象资料,基于统计降尺度模型(SDSM),生成HadCM3气候模式A2和B2两种情景下各站点参考作物腾发量和降水数据。基于联合国粮食及农业组织(FAO)推荐的作物系数法,并考虑有效性降雨和不同地区深层渗漏量,分析历史和未来的水稻灌溉需水时空变化特征。结果表明:过去50年,除了太湖流域以外的长江中下游大部分区域的参考作物腾发量和水稻需水量都呈显著下降趋势,而显著下降的水稻灌溉需水量主要位于鄱阳湖流域;未来两种情景下,参考作物腾发量、水稻需水量和水稻灌溉需水量均值都呈下降趋势,但水稻灌溉需水量降幅最小;水稻需水量和水稻灌溉需水量在长江中下游地区的变化趋势具有明显的空间异质性,水稻需水量大幅减少的区域由太湖流域向汉江和洞庭湖流域扩展。未来水稻灌溉需水量减少的区域主要分布在太湖流域、汉江流域东部和洞庭湖流域北部,并随时间推移呈扩大趋势。     

Rice research for food security and sustainable agricultural development in Asia: Achievements and future challenges

Rice is the major staple food of Asia, and an important source of employment and income in rural areas, particularly in low-income countries. Research has contributed significantly in achieving food security by increasing the yield potential of rice in irrigated systems, reducing the crop maturity period and achieving yield stability by developing resistance against major insects and diseases in the modern high-yielding varieties. Poverty is, however, still extensive in fragile rainfed rice ecosystems where rice yield has remained low, as scientists have yet to develop high-yielding varieties resistant to abiotic stresses and problem soils. Rice production needs to be increased by another 70% over the next 30 years to meet growing food needs. This has to be achieved with less land, less water, and less labor to accommodate the demand for these inputs from the expanding nonagricultural sectors. The challenge to the rice research community is to make further shifts in yield potential of rice for the irrigated systems, to close the yield gaps in the rainfed systems through developing resistance of high yielding varieties to abiotic stresses, and greater understanding of the interactions between genotypes and environment, developing durable resistance against pests and diseases to reduce farmers' dependence on harmful agrochemicals, and to increase efficiency in the use of water, labor and fertilizers. As further intensification of rice cultivation is inevitable, scientists must understand the negative environmental side-effects of increasing rice productivity, to develop appropriate mitigation options.     

Effect of agrochemicals on macroinvertebrate assemblages in Pampasic streams,Buenos Aires,Argentina

Agricultural practices have been intensified in recent decades in Argentina. The Pampa plain is the main agricultural region of the country. The effect of increased application of agrochemicals on the invertebrate fauna of the Pampasic streams remains unreported. In the present study, we compared the abundance and composition of invertebrate assemblages in seven Pampasic streams with contrasting soil use in their basins. Two streams run through intensively cropped plots, two drain basins with livestock fields, while the other three are located within a biosphere Reserve. Higher nutrient and insecticide concentrations were measured in the streams draining cropped basins, related with pesticide applications and crop fertilization. The invertebrate assemblage composition of the cropped streams differed significantly from the others and between the two. Present evidence suggests that the impact of agrochemicals results in a change in composition with decreased abundance or absence of sensitive species such as Hyalellidae, Caenidae, Baetidae and Curculionidae and increased abundance of more tolerant taxa: Ostracoda, Glossiphoniidae (Hirudinea), Ancylidae (Gundlanchia), Ampullariidae (Pomacea canaliculata), Sphaeriidae and Dugesiidae. Available information suggests that macrophyte cover and composition also influence the invertebrate assemblages of the Pampasic streams.     

Determination of organophosphorus insecticide residues in the rice paddies

In most rice paddies in Mazandaran Province, diazinon is applied to control Chilo suppressalis. Due to the extensive application of insecticides in the rice paddies of the Caspian coasts of Iran, this investigation was carried out on the rice fields in order to obtain the necessary data and information on the concentration of insecticide residues. A total of 125 samples were taken from five areas of Amol township in 2007. Then, according to the analysis of variance procedures, the water samples were statistically analyzed after the spraying of diazinon. Results indicate that the insecticide was used frequently to control stem boring caterpillar of rice. The residuals of this toxic chemical were observed in the majority of stations from the day after the spraying until one to two months later. The greatest level of diazinon was observed in station 1 in amount of 1.14 ppm. This study revealed that the physical and chemical properties of the studied diazinon such as fumigation characteristic as well as the ecological conditions and soil type influence the reduction and eventual removal of the insecticides during the cultivation and harvest periods.     

Experimental research on the effect of slope morphology on bank collapse in mountain reservoir

Farmers along the Amazon River each year face multiple natural hazards that threaten crop production and limit the potential for agricultural development of the expansive floodplain and active channel. In this paper we report the findings of a study of natural hazard-related risk associated with rice production on silt bars in the active channel of the Amazon River near Iquitos, Peru. Data were gathered in four rice producing communities in 2014 using household surveys (n = 83 households), focus group discussions, surveying of land elevations along the Amazon River, and interpretation of remote sensing imagery. The probability, extent, and severity of rice crop shortfalls were estimated for recent production years and the economic losses to farming households were also assessed. Our findings point to a very high risk of crop shortfalls due to natural hazards, suggesting that a good year brings rice farmers bounty and a bad year, near penury. River stage reversals (repiquetes) and edaphic conditions were found to be more problematic than the often cited hazard of high and/or early floods. Also surprisingly, farmers’ perceptions of hazards and risk diverged markedly from actual shortfalls experienced during the production years studied. Our results provide the first quantitative estimates of risk due to the multiple natural hazards along the Amazon River and point to the need to assist lowland farmers with risk mitigation so as to unlock the considerable potential of Amazon floodlands for agricultural production.     

The landscape context of Anasazi pebble-mulched fields in the Galisteo Basin,Northern New Mexico

Anasazi farmers in northern New Mexico occasionally applied a pebble mulch to their gardens during the 14th and 15th centuries A. D. to increase crop yield and to buffer against drought. Regional variations in surface geology and soils are compared to the distribution of pebble-mulch gardens near Pueblo San Marcos in the Galisteo Basin, south of Santa Fe. The slope angle and aspect of 96 individual garden plots are also examined to determine the role of microenvironment as a siting consideration within the broader geological-pedological context. It is found that Anasazi pebble-mulch gardens were consistently sited on south-facing, relatively flat slopes of erosional benches, within naturally occurring surface/near surface deposits of gravel. This suggests that the Anasazi intentionally exploited regionally scaled variations in geology and soils in their pursuit of agricultural diversification. © 1993 John Wiley & Sons, Inc.     

Pesticides in export and domestic agriculture: Reconsidering market orientation and pesticide use in Costa Rica

The environmental impact of agro-export production in developing countries remains an important research topic. The political economy-inspired literature on developing country agro-exports maintains that export crops are pesticide intensive – or, more generally, environmentally destructive – while local and national market crops are less pesticide intensive, or environmentally benign. If used to draw conclusions about the impact of national market versus export market expansion, this view has significant limitations, most importantly the comparison of high-commodity value export crops with low-commodity value crops for national market. To overcome this and other limitations of prior analyses, this paper addresses the question: how does market orientation influence pesticide intensity where the same crops are grown for both the national market and for export? Data from a survey of Costa Rican vegetable farmers are used to compare pesticide intensity of 27 vegetable crops, five of which are produced for both national and export markets. The general pattern that emerges is that national market vegetables are more pesticide intensive than export vegetables in the area. Yet, controlling more for the crop variable is important, and specific comparisons of the five vegetables grown for both markets – carrot, chayote, corn, green beans, and squash – illustrate that market orientation alone does not determine pesticide intensity, but that it is jointly influenced by regulatory risk, crop value, and pest susceptibility, among other factors. Continued attention to both political economy and ecological processes in “second nature” will allow political ecology to make important contributions to understanding pesticide problems and implementing agroecological solutions.     

A field study investigating the potential use of phosphorus combined with organic amendments on cadmium accumulation by wheat and subsequent rice

A field study was performed to determine the efficiency of diammonium phosphate (DAP) applied alone or combined with biochar, lignite, and farmyard manure (FYM) on growth and cadmium (Cd) accumulation in wheat and rice. Before crop sowing, different treatments were applied in the field such as a control (T₁), DAP alone (0.1%, T₂), DAP + lignite (0.05% each, T₃), DAP + FYM (0.05% each, T₄), and DAP + biochar (0.05% each, T₅). Afterwards, the wheat seeds were sown in the soil. At wheat postharvest, rice was sown without any further treatment. Raw effluent was applied as an irrigation source during the whole growth period of both crops since it is the common practice of the farmers of study area. It was revealed that the use of amendments enhanced the yield and photosynthesis but lowered the Cd contents in straw as well as grains of both crops. In both crops, the highest yield of straw and grain was found in DAP + FYM whereas the lowest Cd concentration was found in DAP alone. The ammonium bicarbonate-DTPA extractable Cd of post wheat and post rice soils were decreased while the soil pH and immobilization index were increased in all treatments as compared with the control. The present field study highlighted that the DAP + FYM can be effective in increasing yield with decreased Cd concentrations in crop grains.     

Of yield gaps and yield ceilings: Making plants grow in particular places

The System of Rice Intensification (SRI) and rice genetic improvement are proposed as two approaches to improving and increasing rice production. In recent exchanges, they have been represented by their respective supporters as starkly contrasting, almost mutually incompatible alternatives. However, advocates on both sides of this argument have tended to stress the genetic and physiological characteristics of rice plants and place less emphasis on the spatially and temporally situated knowledge and management skills of farmers, which are the means by which any agricultural technology is locally adapted and integrated into livelihood strategies, and technological potential is translated into real outcomes in specific settings. Taking this proposition seriously would entail a substantial reorganisation of agricultural research and extension, bridging the historical divide between these two wings of professional agronomy. It would require agronomists of both types to work more collaboratively with farmers. It would also require scientists to produce new kinds of outputs, such as analytical frameworks, heuristics and decision-making tools to help farmers apply scientific insights to their own constrained circumstances. This argument is made with reference to the cases of SRI (a cultivation system that is said to boost farm yields without the need for genetically improved germplasm) and C4 rice (a crop-improvement project intending to ‘supercharge’ rice photosynthesis to increase rice yields). The paper uses the agronomic concepts of the ‘yield gap’ and the ‘yield ceiling’ to offer a perspective on strategic questions about the goals and organisation of agricultural research and extension.     

Intensification of irrigated rice systems: Learning from the past to meet future challenges

More than 75% of all rice is produced on irrigated land. Although the green revolution was driven by both an expansion of irrigated rice area and increased yield per unit land area, the next quantum leap must come exclusively from increasing yields on existing crop land. We review the structural changes that have accompanied the intensification process, and examine the major biophysical and economic challenges that confront Asian farmers who must further intensify irrigated rice systems to achieve a yield increase of more than 60% by the year 2025.     

Afforestation of European landscapes: How do different farmer types respond to EU agri-environmental schemes?

This paper investigates how different types of farmers manage the landscape with primary emphasis on farmland afforestation, planned landscape changes, and the extent to which EU agri-environmental schemes take farm type specific characteristics into account in information strategies. The empirical data concern landscape practices of more than 2,000 landowners in 16 European areas in eight countries who were surveyed using quantitative questionnaires. Supplementary in-depth interviews were conducted for two case areas in Denmark to further investigate the role of the policy information environment. The analysis is based on a categorization of the farmers into hobby, part-time, full-time and retired farmers. This study shows that hobby farmers constitute a high proportion of landowners and manage a large part of the rural landscape. At the same time, hobby farmers are relatively more interested in landscape changes and differ from other landowners by considering farmland afforestation more often than full-time landowners, for example. Yet, 40% of the hobby farmers who are considering farmland afforestation are not familiar with the agri-environmental scheme for farmland afforestation. One reason may be their low membership rate in traditional information networks such as farmers’ or foresters’ associations, as revealed by the in-depth analysis of the cases in Denmark. Thus, it is proposed that policy impact may be improved if farmer type specific differences are explicitly taken into account in the scheme logistics for EU agri-environmental schemes.     

Contesting expertise: The politics of environmental knowledge in northern Indian groundwater practices

The world is facing a severe water crisis. According to the UN, by 2025 50% of the world’s population will face water scarcity. In India, where 70% of irrigation and 80% of domestic needs are met with groundwater, demand for this resource is expected to exceed supply by 2020. This has led to recent calls for groundwater governance reforms within India, and specifically within the state of Rajasthan, where no regulation exists today. The success of these reforms hinges on the interaction of the state and its agents with local users and managers of groundwater resources. Underpinning these encounters, though, are tensions between local and state forms of groundwater knowledges. The question analyzed here is in what ways do conflicting environmental knowledges adversely affect the management of overexploited groundwater resources in water-scarce India? To address this question, I examine the coevolution of pre-colonial, colonial, and post-independence groundwater and irrigation knowledges and technologies in Rajasthan, India to expose the ways that they are produced, contested, legitimated, and hybridized. The paper argues the following three claims. First, the relationship between the state and local producers of groundwater knowledge practices is non-linear and porous. For instance, the way that state subjects experience the state is uneven because within and in-between historical moments the state may attempt to assimilate, reorganize, plagiarize, or disparage local knowledge. Second, these attempts produce or exacerbate existing historically rooted tensions between farmers and state groundwater engineers. But in response, farmers often seek out non-state avenues of expertise, such as tubewell drilling firms. This results in the further hybridization of knowledge practices and also in the present-day marginalization of the state. Third, the relationship between farmers and the state is further strained because of a current lack of state visibility in the study area and also because the state continues to “see like a state”. These shifting meanings and power relations around groundwater and irrigation knowledges produce tensions that will undoubtedly negatively impact future groundwater governance strategies.     

Determinants of farmers’ choice of coping and adaptation measures to the drought hazard in northwest Balochistan,Pakistan

This study identifies the coping and adaptation behavior of the farm households and also examines the factors that influence farmers’ choice for drought-induced adaptation strategies. The study employs a multivariate probit model on 215 farm households’ survey data from northwest Balochistan, Pakistan. The findings reveal that the farmers have shown considerable fortitude in coping with the impacts of drought on their agro-based practices and employed several adaptation initiatives both at on-farm and off-farm levels. These include crop management, water management, adjustment in agricultural inputs, income diversification, economization of expenditure and consumption smoothing, migrating to other places to seek alternative sources of income, assets depletion, and borrowing. Empirically, it is depicted that landholding, annual income, livestock ownership, credit access, farmer-to-farmer extension, GOs/NGOs support increase the probability of farmers’ decision to cope and adapt better with drought hazard. This study implies for specific policy and practice-oriented solutions in order to cope with and adapt in drought situation.     

Surface water and groundwater dynamic interaction models as guiding tools for optimal conjunctive water use policies in the central plain of Thailand

Many irrigation projects in the central plain of Thailand are not capable of providing sufficient surface water for the cultivation of rice, which is the major cash crop for Thai farmers. To overcome this surface water deficiency, which has been exacerbated in recent years by climate change, groundwater is increasingly being used for irrigation. Thus, large sections of agriculture lands have been converted to conjunctive water use regions. While conjunctive water use may be a suitable option to overcome the temporary water shortages on a short-term basis, it may pose a particular threat to the overall water resources in the long term, if not properly managed. As a remedy, conjunctive water management policies ought to be adopted. Conjunctive water management is basically a tool to optimize productivity, equity, and environmental sustainability through simultaneous management of surface water and groundwater resources. As of now, such a comprehensive approach has not been yet employed in the upper Chao Phraya basin of Thailand, and the present study is one of the first of this kind. The study region is the Plaichumpol Irrigation Project (PIP) where conjunctive water use has become indispensable for meeting the increasing water requirements for farming. To get a first grip on the issue, water demand, supply and actual use in the study area were investigated for the purpose of providing possible guidelines for optimal water exploitation. A numerical groundwater model with a special module for simulating surface-groundwater interaction was applied in the PIP area to understand the impact of the farmer’s irrigation behavior on the dominant hydrological processes that determine the seasonal and multi-annual water availability in the irrigation area. A set-up of different agricultural water allocation schemes that depend on the local weather conditions and the regional management rules are examined by the numerical models. The results of the simulations provide adaptation guidelines for the proper management of the conjunctive water resources, namely, optimal water utilization. The numerical results for the surface groundwater in particular indicated that while the irrigation canals recharge water to the aquifer during both dry and wet season, small amounts of discharge from the aquifers to the canals occur only during the wet season. The analysis of the groundwater balance also showed that the present available groundwater potential is not fully exploited by the farmers, especially during the dry periods of surface water shortage. In contrast, the adoption of an optimal conjunctive management scheme would ensure extra water availability for additional annual rice crops in the region.     

Comparative analysis of heavy metal concentration in secondary treated wastewater irrigated soils cultivated by different crops

The use of treated urban wastewater for irrigation is a relatively recent innovation in Botswana and knowledge is still limited on its impact on soil heavy metal levels. The aim of this study is to analyze and compare heavy metal concentration in secondary wastewater irrigated soils being cultivated to different crops: olive, maize, spinach and tomato in the Glen Valley near Gaborone City, Botswana. The studied crop plots have been cultivated continuously under treated wastewater irrigation for at least 3 years. Most crop farms have sandy loam, loamy sand soils. Based on food and agriculture organization, heavy metal threshold values for crop production have been studied. Results showed that the wastewater irrigated soils in the Glen Valley have higher cadmium, nickel and copper than desirable levels, while the levels of mercury, lead and zinc are lower than the maximum threshold values recommended for crop production. The control sites show that the soils are naturally high in some of these heavy metals (e.g copper, zinc, nickel) and that crop cultivation under wastewater irrigation has actually lowered the heavy metal content. Comparing between the crops, mercury and cadmium levels are highest in soils under maize and decline linearly from maize to spinach to olive to tomato and control site. By contrast, concentrations of the other metals are at their lowest in maize and then increase from maize to spinach to olive to tomato and to control site.     

Value of Climate Forecasts for Adjusting Farming Strategies in Sub-Saharan Africa

Sustaining and increasing crop production and productivity has to be a major policy thrust for developing countries. Using a simulation approach different production strategies were evaluated conditioned on climate information to derive optimal strategies to help farmers reduce risk and increase productivity. By examining the existence of options in this case planting dates the study provides an analyses of the expected value and risks associated with changing decisions based on the availability of climate forecasts. The 15-March planting date produced the highest mean yield for the two cultivars examined although 1-April, 15-April and 1-May plantings had one to zero probability of crop failures compared to 15-March with crop failures in 4 out of 20 years. Results indicate losses of between 25 and 35 kg/day due to delays in planting from 15-March planting to 1-June planting for the 120- and 150-day cultivar. El niño years were associated with positive yield deviations for both cultivars and most planting dates. Farmers are known to make tactical adjustments to their management in light of information perceived relevant to the prospects of forthcoming crop. Although in its present form most current forecast products do not provide information on onset of the rainfall, however the information they do provide could play a crucial role in helping farmers reduce the risks posed by climatic variability.