Economics of enhanced micronutrient density in food staples

The combining of benefits for human nutrition and agricultural productivity, resulting from breeding staple food crops which are more efficient in the micronutrient metal uptake from the soil, and which accumulate more micronutrients into their seeds, results in extremely high ex ante estimates of benefit/costs ratios for investments in agricultural research in this area. This finding derives from the confluence of several complementary factors:

• •Rates of micronutrient malnutrition are high in developing countries, as are the consequent costs to human welfare and economic productivity.
• •Because staple foods are eaten in large quantities every day by the malnourished poor, delivery of enriched staple foods (fortified by the plants themselves during growth) can rely on existing consumer behavior.
• •A significant percentage of the soils in which these staple foods are grown are `deficient' in these micronutrient metals, which has kept crop yields low. In general, these soils in fact contain relatively high total amounts of micronutrient metals. However, because of binding to soil constituents, these nutrients have poor soil availability to staple crop varieties that are currently available to farmers.
• •Adoption and spread of nutritionally-improved varieties by farmers can rely on profit incentives, either because of agronomic advantages on trace mineral-deficient soils or incorporation of nutritional improvements in the most productive varieties being released by agricultural research stations.
• •Benefits to relatively small investments in agricultural research may be disseminated widely, potentially accruing to hundreds of millions of people and millions of hectares of cropland.
• •Benefits from breeding advances, derived from initial, fixed costs, typically do not involve high recurring costs, and thus tend to be highly sustainable as long as an effective domestic agricultural research infrastructure is maintained.

     

Micronutrient bioavailability techniques: Accuracy,problems and limitations

Within the scientific agricultural community it is widely known that the total micronutrient content of soils is not a useful measure of the amount of `available' micronutrients to plants. Thus, soil tests have been developed to determine the amounts of micronutrients in soils available to plants for growth. This same concept applies to plant foods eaten by humans because not all of the micronutrients in plant foods are available (i.e. bioavailable) for absorption and or utilization. Antinutrients and promoter substances within plant foods that can either inhibit or enhance the absorption and/or utilization of micronutrients when eaten. As a result, numerous techniques have been developed to determine the amounts of bioavailable micronutrients present in plant foods when consumed in mixed diets with other dietary constituents that can interact and affect the micronutrient bioavailability. Unfortunately, micronutrient bioavailability to humans fed mixed diets is still a confusing and complex issue for the human nutrition community. Our understanding of the processes that control micronutrient bioavailability from mixed diets containing plant foods is relatively limited and still evolving. It remains the subject of extensive research in many human nutrition laboratories globally. This article reviews some of the numerous methodologies that have arisen to account for the bioavailability of micronutrients in plant foods when eaten by humans.     

Agronomic approaches for improving the micronutrient density in edible portions of field crops

Increased micronutrient density in grain destined for human consumption may alleviate micronutrient deficiencies (Fe, Zn, Cu, and I) in human populations around the world. The review of literature indicates that fertilization with inorganic and organic forms of micronutrients has a potential to increase their concentrations in grain. The most effective fertilization could be via soil (for Zn and, to some extent, Cu), foliarly (for Fe) and by adding fertilizers to the irrigation water (for iodine). Care should be exercised not to overfertilize crops with micronutrients because of consequent toxicity and losses in quality and quantity of grain yield. Effectiveness of various agricultural measures in increasing micronutrient density depends on soil type, crop, cultivar, rotation, and environmental and other factors, thus necessitating development of a specific set of measures for individual regions. Agricultural measures would need to be supplemented with appropriate changes in the milling technology to ascertain that increased micronutrient concentrations in some grain parts are passed into the food chain.     

Management of Soil Micronutrient Deficiencies in the Rice-Wheat Cropping System

Summary

Within the last three decades, the rice-wheat cropping system has triggered, and with time, aggravated soil micronutrient deficiencies in the Indo-Gangetic Plains (IGP). This has largely been due to the shift from an earlier rice and wheat monoculture with low yielding, long duration indigenous varieties, to an intensive rice-wheat rotation cropping system with short duration modern high yielding varieties on the same piece of land. The problems related to micronutrient deficiency in the IGP are more due to the size of its available pools in the soil rather than its total contents and are greatly influenced by crop management, or rather its mismanagement. Deficiency of zinc is widespread in the IGP, but with the extensive use of zinc sulfate, zinc deficiency has reduced in some areas of the region. Meanwhile, the deficiency of Fe, Mn and B has increased in the IGP. Deficiency of Cu and Mo is location specific and can limit rice and wheat yields. The adoption and spread of the rice-wheat system in permeable coarse textured soils, particularly in the western IGP, not only caused iron deficiency in rice but also resulted in the emergence of manganese deficiency in wheat. In highly calcareous and acidic soils, boron is the next limiting micronutrient in crop production after zinc. Bumper rice and wheat harvests in the past decade, the declining use of organic manures in the region and except for the widespread use of zinc sulfate, a general lack of awareness amongst farmers on micronutrient deficiency problems has contributed to micronutrients limiting rice and wheat yields in the IGP. Approaches to alleviating micronutrient deficiencies include matching the crop removals of the micronutrients with its replenishments through their respective external carriers, supplementation through organic sources and mobilization/utilization through cultivation of micronutrient efficient crop cultivars. Identification of efficient micronutrient carriers and finding the optimum rate, mode and time of its application is important in ameliorating the micronutrient deficiencies. This article reviews the extent of micronutrient deficiency and discusses various management options available to reduce micronutrient deficiency induced crop yield reduction for rice and wheat in the Indo-Gangetic Plains.     

海南岛东北部地区土壤农业地球化学评价

土壤的大量营养元素、微量元素分析结果表明,海南（琼）东北部地区土壤农业环境质量好,达到国家一级标准,是热带优质作物的理想生产基地.相对来说,母质为基性火山岩的土壤农业地球化学质量最好,水稻土壤次之,母质为花岗岩和砂页岩土壤较好,母质为浅海沉积物的土壤较差,冲积土壤最差.     

土壤性状和营养物质对小麦品质的影响

在影响小麦品质的环境因素中，土壤性状和营养物质的影响极为重要。高肥力和较干燥的土壤条件更有利于生产强筋优质小麦，其他土壤性状如土壤质地、性质、结构等也会影响小麦品质。营养物质供应状况影响小麦植株体内的物质代谢，进而影响其品质。氮素是影响小麦品质的最主要因素，施氮量、施氮时期、施氮方式等，均能显著影响小麦品质；磷素和钾素品质效应一般不明显，只有氮、磷、钾适当配比才能有效提高品质；一般条件施用中、微量元素对品质基本无正效应，但缺素或有效含量不足的土壤只有针对性施中、微量元素肥才能保证小麦品质。     

Enhancing the mineral and vitamin content of wheat and maize through plant breeding

More than half of the world's population suffers micronutrient undernourishment. The main sources of vitamins and minerals (iron, zinc, and vitamin A) for low-income rural and urban populations are staple foods of plant origin that often contain low levels or low bioavailability of these micronutrients. Biofortification aims to develop micronutrient-enhanced crop varieties through conventional plant breeding. HarvestPlus, the CGIAR's biofortification initiative, seeks to breed and disseminate crop varieties with enhanced micronutrient content that can improve the nutrition of the “hard to reach” (by fortification or supplementation programmes) rural and urban poor in targeted countries/regions. In attempting to enhance micronutrient levels in maize and wheat through conventional plant breeding, it is important to identify genetic resources with high levels of the targeted micronutrients, to consider the heritability of the targeted traits, to explore the availability of high throughput screening tools and to gain a better understanding of genotype by environment interactions. Biofortified maize and wheat varieties must have the trait combinations which encourage adoption such as high yield potential, disease resistance, and consumer acceptability. When defining breeding strategies and targeting micronutrient levels, researchers need to consider the desired micronutrient increases, food intake and retention and bioavailability as they relate to food processing, anti-nutritional factors and promoters. Finally, ex ante studies are required to quantify the burden of micronutrient deficiency and the potential of biofortification to achieve a significant improvement in human micronutrient status in the deficient target population in order to determine whether a biofortification program is cost-effective.     

Enhancing the mineral and vitamin content of wheat and maize through plant breeding

More than half of the world's population suffers micronutrient undernourishment. The main sources of vitamins and minerals (iron, zinc, and vitamin A) for low-income rural and urban populations are staple foods of plant origin that often contain low levels or low bioavailability of these micronutrients. Biofortification aims to develop micronutrient-enhanced crop varieties through conventional plant breeding. HarvestPlus, the CGIAR's biofortification initiative, seeks to breed and disseminate crop varieties with enhanced micronutrient content that can improve the nutrition of the “hard to reach” (by fortification or supplementation programmes) rural and urban poor in targeted countries/regions. In attempting to enhance micronutrient levels in maize and wheat through conventional plant breeding, it is important to identify genetic resources with high levels of the targeted micronutrients, to consider the heritability of the targeted traits, to explore the availability of high throughput screening tools and to gain a better understanding of genotype by environment interactions. Biofortified maize and wheat varieties must have the trait combinations which encourage adoption such as high yield potential, disease resistance, and consumer acceptability. When defining breeding strategies and targeting micronutrient levels, researchers need to consider the desired micronutrient increases, food intake and retention and bioavailability as they relate to food processing, anti-nutritional factors and promoters. Finally, ex ante studies are required to quantify the burden of micronutrient deficiency and the potential of biofortification to achieve a significant improvement in human micronutrient status in the deficient target population in order to determine whether a biofortification program is cost-effective.     

Micronutrient Fertilizers

Summary

Micronutrient fertilizer sources are mostly sulfates for Zn, Cu, and Mn, but chelates are the usual Fe source, and borax and sodium molybdate are used for B and Mo, respectively. Soil pH is the soil property that most influences micronutrient availability, and for all but Mo, the higher the soil pH, the lower is the plant availability. For Mo, liming can actually prevent deficiencies. Other soil properties that are important in bioavailability are organic matter content, especially for Cu, oxidation/reduction conditions, especially for Fe and Mn, soil texture, Fe and Al oxide content and soil moisture conditions.     

Micronutrient concentrations in common and novel forage species and varieties grown on two contrasting soils

We investigated differences between forage species with regard to micronutrients that are essential to sustain livestock health. Five grasses (timothy, perennial ryegrass, meadow fescue, tall fescue and cocksfoot), three legumes (red clover, white clover and birdsfoot trefoil) and four forbs (ribwort plantain, salad burnet, caraway and chicory) were grown on one micronutrient‐poor/low pH soil and one micronutrient‐rich/high pH soil (outdoor pot experiment). In addition, six grasses (timothy, perennial ryegrass, meadow fescue, tall fescue, Festulolium hybrid and cocksfoot) and one legume (red clover) were field‐grown on the micronutrient‐poor soil. Of the twelve pot‐grown species, herbage of chicory, red clover and white clover generally had the highest micronutrient concentrations (maximum Co, Cu, Fe and Zn concentrations were 0·23, 9·8, 233 and 109 mg kg^?1 DM, respectively), except for Mo, which was highest in the clovers (10·6 mg kg^?1 DM), and Mn, which was highest in cocksfoot (375 mg kg^?1 DM). Soil type had the strongest effect on plant Mo and Mn concentrations. We also investigated differences in micronutrients between varieties, but they were generally few and negligible. The results indicate that choice of forage species is of major importance for micronutrient concentrations in herbage and that soil type exerts a major effect through pH. Forage of chicory, red clover and white clover generally met the requirements of high‐yielding dairy cows with regard to most micronutrients; therefore, diversification of seed mixtures so as to include these species could increase micronutrient concentrations in forage.     

绿肥翻压对土壤微量元素含量及玉米吸收的影响

选取9个春油菜绿肥品种进行田间试验,连续翻压两年后,测定土壤和玉米子粒中的微量元素含量,研究比较不同春油菜绿肥品种翻压对土壤微量元素含量及玉米吸收情况的影响。结果表明,中油肥1804翻压后土壤全量铁、锰和锌含量较春闲田CK处理分别提高了9.31%、5.71%、9.97%,土壤有效态铁、锰、锌含量较春闲田CK处理分别提高37.31%、62.35%、73.99%;中油肥1907翻压后土壤全铜含量较春闲田CK处理显著提高了84.29%;中油肥1901翻压后较春闲田CK处理显著提高了玉米子粒铁、锰、锌的吸收量及玉米产量和品质。不同春油菜绿肥品种翻压后土壤有效态铜含量、玉米子粒铜及锰含量与春闲田CK处理之间差异不显著;土壤有效态微量元素含量与春油菜中微量元素和土壤全量微量元素含量之间存在线性关系,且微量元素与玉米叶片叶绿素、含氮量、产量、可溶性糖、蛋白质呈显著或极显著正相关。华北地区种植并翻压中油肥1804、中油肥1901、中油肥1907能较好地提高土壤微量元素含量、生物有效性及玉米产量和品质。     

小麦籽粒微量元素含量的研究进展

以禾谷类作物为主食引起的人体摄取必需微量元素(特别是Fe和Zn)不足,已对现代社会和谐发展造成沉重的经济负担和安全隐患。小麦(Triticum aestivumL.)是中国和全球大多数人主要的食物和矿质元素来源。小麦籽粒中Zn、Fe含量普遍较低,已引起国内外学者们的高度关注。本文综述了小麦籽粒微量元素含量器官间、基因型间的差异及其影响因素和相关性状研究进展,介绍了小麦籽粒吸收和富集微量元素的生理与遗传基础,展望了提高小麦籽粒微量元素的研究内容和方向。     

中国大豆磷素营养及磷高效品种筛选最新进展

磷是影响植物新陈代谢和生长发育的重要元素,但由于其极易被土壤固定,因而有效性非常低.缺磷已成为限制当前农作物产量提高和品质改良主要因素之一,传统农业生产一般通过施肥和土壤改良来提高植物对磷素的利用率.近年来,有学者提出通过发掘和利用磷高效品种来解决植物需磷和土壤供磷矛盾的新途径.文章综述了中国土壤磷素营养及其遗传改良的...     

Cropping Systems and Soil Quality

SUMMARY

Cropping system refers to temporal and spatial arrangements of crops, and management of soil, water and vegetation in order to optimize the biomass/agronomic production per unit area, per unit time and per unit input. Soil quality refers to its intrinsic attributes that govern biomass productivity and environment moderating capacity. It is the ability of soil to perform specific functions of interest to humans. Three components of soil quality (e.g., physical, chemical and biological) are determined by inherent soil characteristics, some of which can be altered by management. Soil quality and soil resilience are inter-related but dissimilar attributes. Resilient soils, which have the ability to restore their quality following a perturbation, have high soil quality and vice versa. Decline in soil quality sets-in-motion degradative processes, which are also of three types, namely physical (e.g., compaction, erosion), chemical (e.g., acidification, salinization) and biological (e.g., depletion of soil organic matter content). Soil degradation, a biophysical process but driven by socioeconomic and political causes, adversely affects biomass productivity and environment quality. Determinants of soil quality are influenced by cropping systems and related components. Dramatic increases in crop yields during the 20th century are attributed to genetic improvements in crops, fertilizer use, and improved cropping systems. Dependence on fertilizers and other input, however, need to be reduced by adopting cropping systems to enhance biological nitrogen fixation and use efficiency of water and nutrients through conservation tillage, cover crops, and improved methods of soil structure and nutrient management.     

水稻因土质施肥方法探讨

土壤质地是土壤的基本物理性质之一,反应土壤中不同大小直径成土颗粒的组成状况。不同质地土壤间养分含量、蓄水导水、保肥供肥、保温导热、耕性、微生物种类及其活动等性能的差异,影响肥料的固定、转化、吸收和流失,并影响作物的产量形成,进而形成区域性的肥料利用效率的差异。水稻肥料利用状况的改善一直是研究热点,但土壤质地对肥料利用和水稻生长的影响研究相对较少。本文简要介绍了不同质地土壤的养分状况和理化性质差异,分析了土壤质地对作物生长发育的影响;并在简要评价测土配方施肥技术的基础上,初步探讨了不同土质土壤的肥料高效施用方法。     

Growth,Metabolism and Yield of Rice Cultivated in Soils Amended with Fly Ash and Cyanobacteria and Metal Loads in Plant Parts

Soil amendment with fly ash(FA) and combined supplementation with N_2-fixing cyanobacteria masses as biofertilizer were done in field experiments with rice. Amendments with FA levels, 0, 0.5, 1.0, 2.0, 4.0, 8.0 and 10.0 kg/m~2, caused increase in growth and yield of rice up to 8.0 kg/m~2, monitored with several parameters. Pigment contents and enzyme activities of leaves were enhanced by FA, with the maximum level of FA at 10.0 kg/m~2. Protein content of rice seeds was the highest in plants grown at FA level 4.0 kg/m~2. Basic soil properties, p H value, percentage of silt, percentage of clay, water-holding capacity, electrical conductivity, cation exchange capacity, and organic carbon content increased due to the FA amendment. Parallel supplementation of FA amended plots with 1.0 kg/m~2 N_2-fixing cyanobacteria mass caused further significant increments of the most soil properties, and rice growth and yield parameters. 1000-grain weight of rice plants grown at FA level 4.0 kg/m~2 along with cyanobacteria supplementation was the maximum. Cyanobacteria supplementation caused increase of important basic properties of soil including the total N-content. Estimations of elemental content in soils and plant parts(root and seed) were done by the atomic absorption spectrophotometry. Accumulations of K, P, Fe and several plant micronutrients(Mn, Ni, Co, Zn and Cu) and toxic elements(Pb, Cr and Cd) increased in soils and plant parts as a function of the FA gradation, but Na content remained almost unchanged in soils and seeds. Supplementation of cyanobacteria had ameliorating effect on toxic metal contents of soils and plant parts. The FA level 4.0 kg/m~2, with 1.0 kg/m~2 cyanobacteria mass supplementation, could be taken ideal, since there would be recharging of the soil with essential micronutrients as well as toxic chemicals in comparative lesser proportions, and cyanobacteria mass would cause lessening toxic metal loads with usual N_2-fixation.     

Trace element bioavailability as exemplified by iron and zinc

Plant foods can be improved as sources of essential micronutrients either by increasing the concentrations of nutrients in the food, increasing the bioavailability of micronutrients in the food, or both of these. Quantities of minerals in edible portions of crops are influenced by numerous complex, dynamic and interacting factors, including plant genotype, soil properties, environmental conditions and nutrient interactions. Similarly, numerous dietary and host factors interact to affect the bioavailability to animals and people of mineral nutrients in plant foods. Micronutrient bioavailability apparently can be improved by either increasing the quantity of substances within plant foods that enhance the absorption and utilization of micronutrients or by decreasing the quantity of dietary antinutrients that inhibit micronutrient absorption; however, processes that control and regulate the bioavailability of trace elements in plant foods consumed in mixed diets are not fully understood. Use of either stable or radioactive isotopes incorporated intrinsically into edible portions of plant foods during plant growth will likely provide the most reliable estimates of the bioavailability of micronutrients consumed in mixed diets. Increasing the dietary supply of staple plant foods rich in trace elements combined with increased knowledge of micronutrient bioavailability from these foods will meaningfully improve the nutritional health and well being of people.     

Advances in Variable Rate Technology Application in Potato in The Netherlands

Precision agriculture is a farming management concept based on observing, measuring and responding to inter- and intra-field variability in crops. In this paper, we focus on responding to intra-field variability in potato crops and analyse variable rate applications (VRAs). We made an overview of potential VRAs in potato crop management in The Netherlands. We identified 13 potential VRAs in potato, ranging from soil tillage to planting to crop care to selective harvest. We ranked them on availability of ‘proof of concept’ and on-farm test results. For five VRAs, we found test results allowing to make a cost-benefit assessment. These five VRAs were as follows: planting, soil herbicide weed control, N side dress, late blight control and haulm killing. They use one of two types of spatial data: soil maps or biomass index maps. Data on costs and savings of the VRAs showed that the investments in VRAs will pay off under practical conditions in The Netherlands. Savings on pesticide use and N-fertilizer use with the VRAs were on average about 25%, which benefits the environment too. We foresee a slow but gradual adoption of VRAs in potato production. More VRAs will become available given ongoing R&D. The perspectives of VRAs in potatoes are discussed.     

Environmental Concerns of Phosphorus Management in Potato Production

Phosphorus (P) losses from agricultural systems are a cause of degraded surface water quality of lakes and streams. In freshwater systems, P is often the most limiting nutrient for algae growth and an increase in P additions to these systems can cause a shift in ecology. These shifts can result in a degradation of the water resource as habitat or for recreation. In an effort to combat the negative effects of agriculture management practices on surface water quality, federal and state regulations require some level of assessment to guide P applications. Areas with large amounts of potato production are of particular concern with respect to P loss since potatoes are a high P demanding crop and are inefficient users of applied P. In many cases, soils in potato production are managed with a higher soil test P concentration compared to other crops and P applications for optimum production exceed P removal. When potato production fields are maintained at high soil test P levels, this may increase the risk of P loss in runoff. However, based on soils and landscape positions where potatoes are grown, there may be little risk of transport. While there appears to be little risk of P loss on low-sloping, sandy soils, output from the Wisconsin Phosphorus Index suggests that more steeply sloping fields can pose some risk, especially when soil test P concentrations exist at above optimum levels. At high soil test P levels, no P may be required for optimum yield in rotated crops, but production practices of these crops may need to be altered to reduce P losses. Furrow-irrigated and tile-drained fields may also pose risks of P loss to the environment. While the P demands of potato are greater than those for most crops, it is likely that most of this P will not be exported via surface runoff. Careful management considerations must be made when producing potatoes on high sloping soils, especially those close to surface water bodies. Future considerations of P management and water quality will focus on assessing leaching risk of P and this contribution to surface waters.     

室内干湿培养对磷肥在热带土壤中的转化和有效性的影响

对海南岛６种类型土壤不同施磷量的室内干湿培养和应用土壤无机磷分极方法，研究水溶性磷肥在热带土壤中的转化和有效性。结果表明；施磷处理经室内干湿培养８ａ，磷在土壤中的转化速率低于盆栽作物条件，特别是土壤Ｏ－ｐ在培养前后变化很微。其中土壤有效Ｐ以年均４．５％的幅度下降，Ａｌ－ｐ和Ｆｅ－ｐ分别年均２．１％和１．７％的幅度下降，而Ｃａ－ｐ则分别以年均１．２％和０．２％的幅度增长。土壤有效磷的变化趋势与Ａｌ－