Crop Nutrient Content Research Articles

The Role of Bio-fortification in Enhancing the Nutritional Quality of Vegetables: A Review

Bio-fortification is a process that enhances the nutritional quality of crops, including vegetables, by increasing their micronutrient content. It can be achieved through different approaches such as agronomic, conventional breeding, and transgenic/biotechnological methods. Vegetables are known to be rich in micronutrients, vitamins, antioxidants, and other health-benefiting compounds, making them essential for a balanced diet. However, malnutrition and hidden hunger continue to be global challenges, particularly in developing countries. Micronutrient deficiencies, such as iron, zinc, iodine, and vitamin A, are prevalent in these populations. Conventional breeding focuses on selecting genotypes with desirable nutritional traits without compromising agricultural productivity. Transgenic/biotechnological approaches involve the synthesis of transgenes to enhance the bioavailability of micronutrients in plants. Bio-fortification of vegetables is particularly important as they are rich sources of micronutrients, vitamins, and other health-benefiting compounds. However, improving the nutritional quality of vegetables through conventional breeding has had limited success, and modern molecular tools and techniques offer potential for handling complex traits and developing nutrient-dense varieties. Bio-fortification offers a sustainable solution to address these deficiencies by increasing the nutrient content of crops, particularly plant-based foods. These techniques have shown promising results in increasing the concentration of nutrients, such as iron, in vegetables, thereby improving their nutritional quality.

Impact of Pesticides on Food Quality and Human Health

This research explores the impact of pesticides on crop quality and food safety. The widespread use of pesticides is a fundamental practice in modern agriculture, aimed at protecting crops from the perils of pests and diseases. However, pesticide usage goes beyond pest control, affecting both crop quality and food safety. Studies indicate that prolonged exposure to specific pesticides, such as organophosphates, can lead to adverse changes in the aroma, taste, and nutrient content of crops, raising concerns about the nutritional value of pesticide-treated produce. Factors influencing pesticide residues, including application timing and soil characteristics, add complexity to managing residue levels in crops. Public awareness and education initiatives are crucial in addressing the potential risks associated with pesticide residues, emphasizing safe food handling practices. A critical worry is how pesticides affect people's health, with chronic health effects including neurotoxicity, carcinogenicity, and reproductive issues. Acute pesticide poisoning remains a pressing global issue, especially in regions with intensive pesticide use. Children, due to their vulnerability, are at higher risk of cognitive development issues linked to pesticide exposure. Regulatory measures play a crucial role in minimizing health impacts. Protecting vulnerable populations, monitoring long-term health effects, and promoting sustainable agricultural practices are essential steps in mitigating the adverse effects of pesticide use.

Genome-wide association mapping of nutritional traits for designing superior chickpea varieties.

Micronutrient malnutrition is a serious concern in many parts of the world; therefore, enhancing crop nutrient content is an important challenge. Chickpea (Cicer arietinum L.), a major food legume crop worldwide, is a vital source of protein and minerals in the vegetarian diet. This study evaluated a diverse set of 258 chickpea germplasm accessions for 12 key nutritional traits. A significant variation was observed for several nutritional traits, including crude protein (16.56–24.64/100 g), β-Carotene (0.003–0.104 mg/100 g), calcium (60.69–176.55 mg/100 g), and folate (0.413–6.537 mg/kg). These data, combined with the available whole-genome sequencing data for 318,644 SNPs, were used in genome-wide association studies comprising single-locus and multi-locus models. We also explored the effect of varying the minor allele frequency (MAF) levels and heterozygosity. We identified 62 significant marker-trait associations (MTAs) explaining up to 28.63% of the phenotypic variance (PV), of which nine were localized within genes regulating G protein-coupled receptor signaling pathway, proteasome assembly, intracellular signal transduction, and oxidation–reduction process, among others. The significant effect MTAs were located primarily on Ca1, Ca3, Ca4, and Ca6. Importantly, varying the level of heterozygosity was found to significantly affect the detection of associations contributing to traits of interest. We further identified seven promising accessions (ICC10399, ICC1392, ICC1710, ICC2263, ICC1431, ICC4182, and ICC16915) with superior agronomic performance and high nutritional content as potential donors for developing nutrient-rich, high-yielding chickpea varieties. Validation of the significant MTAs with higher PV could identify factors controlling the nutrient acquisition and facilitate the design of biofortified chickpeas for the future.

A new Lancet Commission on the future of health and economic resiliency in Africa

The African continent's population, growing at an average of 2·6% per annum, is expected to double by 2050.1,2 Faced with this reality, the continent has urgent challenges as well as opportunities. First, population growth increases demand for resources, in a context where the impacts of climate change on the continent are exacerbated by limited capacity to mitigate the effects on food systems. Climate change is increasing the occurrence of adverse events, such as droughts and flooding, altering the productivity and nutrient content of crops and affecting food security, nutrition, and health.

Retrieval of Paddy Crop Nutrient Content at Plot Scale Using Optimal Synthetic Bands of High Spectral and Spatial Resolution Satellite Imagery

The main aim of the present study is to introduce Hyperion narrow band information into high spatial broad band imagery so that it will be helpful for the estimation of crop parameters at small field scale from multispectral data. Here, we are targeting to retrieve the nitrogen content of summer paddy at plot scale. Our findings concluded that paddy crop heterogeneity can be assessed by implementing narrow band index regression model designed for paddy crop from multispectral LISS IV data. Moreover, the proposed models to construct the synthetic narrow bands in green (GS), red (RS) and NIR (NS) regions of the spectrum for high-resolution satellite imagery (LISS IV) are also presented here {\(GS\rho_{LISS \, IV} = 0.032 \cdot G\rho_{IH} + 17.296\); \(RS\rho_{LISS \, IV} = 0.072 \cdot R\rho_{IH} + 16.025\); \(NS\rho_{LISS \, IV} = 0.087 \cdot N\rho_{IH} + 24.923\)}. It showed the spatial variability of nitrogen content ranged from 3.37–6.04% obtained by leaf nitrogen concentration (LNC: R705, R717, R491) index regression model and 3.82–5.96% by simple ratio (SR: R533, R565) index regression model over a rice agriculture system. Thus, the details of spatial variability at crop field level over a rice agriculture system can be assessed from multispectral LISS IV data with 5.6 m spatial resolution through the synthetic broad bands. The results conclude that narrow band-based index regression model derived from Hyperion bands by implementing band average method can effectively evaluate the nitrogen content distribution of croplands subjected to varying field heterogeneity. It confirmed that the proposed methodology can be applied for the variability mapping of crop parameters at plot-scale level within the fields from space platform, which can be beneficial in achieving operational precision farming more efficiently.

Nutritional quality degradation: A potential risk due to nutrient dilution effects in film-mulched maize

The nutritional quality of crops is sensitive to the planting method and fertilization rate, especially in fields threatened by drought and nutrient deficiencies. Ensuring that the nutrient content of crops is adequate is important in addition to obtaining a high yield in the current agricultural production in China. Thus, a field experiment with two typical mulch planting methods (full plastic film mulching, RFF; half plastic film mulching, RFH) and five fertilization rates (N 0 +P2O5 0 kg ha−1; N 117 +P2O5 59 kg ha−1; N 173 +P2O5 87 kg ha−1 N 229 +P2O5 115 kg ha−1; N 285 +P2O5 143 kg ha−1) was conducted from 2014 to 2016 in a semiarid region, China. The potential effects of film mulching on maize nutritional quality and the differences under different fertilizer rates were studied. The results showed that RFF improved soil water and temperature conditions, and significantly increased the maize grain yield (by 17.2–38.0%) and nutrients uptake (by 14.0–22.3% in nitrogen, 24.8–35.2% in phosphorus) compared with RFH. However, the nutrient contents of plant organs decreased to different extents under RFF compared with RFH, indicating a "dilution effect". In particular, the grain nutrient content decreased by up to 3.6% for nitrogen and 6.5% for phosphorus with fertilization up to N 160 +P2O5 80 kg ha−1, but with an increasing tendency above this rate. In addition, fertilization significantly increased the maize grain yield and nutrient content, but both did not increase significantly above N230 + P2O5115 kg ha−1, and the NUE gradually decreased, especially nitrogen under RFF. Thus, RFF significantly improved the maize yield and nutrients uptake compared with RFH, but there was a risk of nutritional quality degradation, and surprisingly, this effect can be adjusted or even avoided by changing the amount of fertilizer applied. For example, in the study region, both the maize yield and quality of RFF were improved compared with RFH in the fertilization range of N(160−230)+P2O5(80−115) kg ha−1.

Optimized crop growth area composition for long duration spaceflight

This paper presents an optimized composition of crop growth areas for biological life support systems with respect to nutrition and equivalent system mass. For this purpose, crop growth area compositions from literature are compared with compositions derived from an optimization algorithm. The optimization algorithm uses literature data for crop growth rates and crop nutrient content to minimize the required crop growth area required to supply all nutrients for a human. The algorithm derives the required crop growth area per crew member under different dietary boundary conditions and the resulting nutrient supply is compared to reported diets from crops for spaceflight. The primary goal of this optimization is to find the minimal area required to supply all relevant macronutrients. The minimal area for the exact desired composition of macronutrients (carbohydrates, fats and proteins) was 106.86 m² using chard, lettuce, peanut, bell pepper, snap beans and spinach. If a deviation in the macronutrient composition is allowed the required area can be reduced to 39.88 m² of wheat and white potatoes. Since the variety of crops is a relevant factor for long term food supply, a limit of the maximum growth area per crop was introduced to derive a diet with more variety, which resulted in a minimal area of 57.04 m² using drybean, rice, snap beans, sweet potato, wheat and white potato. Based on this result, a further manual adjustment of the crop growth areas was performed to also introduce lettuce and tomato in the crops provided and adjust the remaining crop compositions to receive better macro- and micronutrient conformity while maintaining a crop growth area of 57 m². One major result of this analysis is that soybeans are not the most favorable crop with regard to protein and fat productivity and the focus of NASA crop selection for full nutrient supply on soybean results in exceedingly large required crop areas of 164.15 m². The resulting crop growth areas from both the optimization and literature are then analyzed as plant growth chambers (PGC) in the Life Support Trade-Off Tool (LiSTOT) of the institute of astronautic from the Technical University of Munich (TUM). LiSTOT calculates the impact of the PGC on an ISS based environmental control and life support system (ECLSS) using averaged steady state values for the plants from literature. Based on this result LiSTOT scales the physical chemical systems and calculates the resulting equivalent system mass (ESM) of the different cases. This approach allows the consideration of not only the PGC ESM, but also the impacts the PGC has on other ECLSS systems and their ESM. The ESM values for PGC were updated to assume LEDs instead of high pressure sodium lamps resulting in a new logistic mass of the PGC of 1.28 kg/(y m²) and a lower specific system mass of 87.7 kg/m². The mass balance analysis of carbon within the overall ECLSS lead to a reduction of the plant growth area to 50.6 m² and the break-even time with the ISS ECLSS was calculated to 87.2 years. With more optimistic assumptions for the LED and using urine as nutrient supply this time can be reduced to 14.6 years. The analysis also showed that the derived crop composition is not only favorable regarding nutrient supply but also with regard to the ESM and break-even time compared to previously reported crop compositions. Only the PGC with only wheat and white potatoes has a lower ESM but also provides a less balanced nutrient supply. This PGC is downscaled to 37.55 m² to achieve carbon balance and a break-even time of 38.4 years or 10.3 years with the optimistic assumptions.

Rising carbon dioxide is decreasing nutrition in crops and endangering health among the less wealthy

Carbon dioxide levels are rising globally. The increasing CO2 levels reduce the concentration of nutrients in many of the crops that are consumed worldwide (wheat, rice, barley, maize, legumes, and potatoes). The larger effects for human health are concentrated in regions that heavily rely on these crops for their nutrition such as South and Southeast Asia, North Africa, and the Middle East. Because these effects are likely to be hidden, we should better monitor the nutritional status of populations as well as crop nutrient content over the coming decades.

Sustainable Crop Production Systems and Human Nutrition

There is a pressing need for redesigning agriculture to achieve sustainability and for utilizing modern genetic tools, including genetic engineering, to add nutritional value to crops for the benefit of the diverse human population. Collectively, plant foods contain most minerals, macronutrients (calories), and micronutrients essential for human nutrition. These plant foods also contain a range of bioactive compounds that can play important roles in the prevention of chronic diseases including heart disease, cancer, stroke, diabetes, Alzheimer’s, cataracts, and age-related functional decline. However, these bioactive nutrients are often present at marginal concentrations in edible plant tissues in regard to human nutrition/prevention of disease. The quantity of these nutrients in edible plant tissues is primarily dependent on crop genetics and regulated by complex and overlapping mechanisms in response to developmental and environmental cues. Environmental cues are naturally occurring - temperature, light intensity and other stressors, or result from crop production system components - fertilizer, tillage operations, etc. One strategy for sustainable, next-generation crop development is to design cropping systems that have minimal or lesser impact on the environment and to use genetic approaches to enhance crop nutritional content. This strategy is appealing since crop genetics is the primary driver of plant nutrient content and because purely managing crop production fields to optimize crop nutrient content is extremely challenging if not impossible. As an example we present the development of a next-generation sustainable tomato production system with beneficial impacts on tomato physiology and nutritional quality of the tomato fruit. Our analysis of the metabolomes of tomato cultivars in this and other cropping systems highlights the need for robust cultivars that consistently express nutritional and other desirable traits across cropping systems and under differing environmental conditions.

Nutrient content monitoring of potato plant based on spectrum device

The nutrient estimation is an important basis for water and fertilizer management in the field. In order to achieve crop nutrient content for variable-rate fertilization, a spectrum device based on the Ocean Optics STS-VIS sensor was developed to measure the spectral reflectance at 350-800 nm. The spectral reflectance data could be measured by optical sensor, data transmission module and the controller. The control software was developed with functions such as acquisition parameters, acquisition control and data management. Before the field application, the calibration experiments were conducted. The correlation was analyzed between the developed device and ASD Field Spec Hand Held 2. The result showed that the average correlation coefficient value was 0.94. It was used to detect the chlorophyll and moisture content of potato plant. The SPAD regression model was established and the determinant coefficient R2 was 0.484, moisture content regression model was established and R2 was 0.735. Results showed that the device has a certain ability to predict chlorophyll content and moisture content of potato leaf.

Identifikasi Sistem Budidaya, Pemanfaatan dan Analisis Nutrisi Sayur Hitam (Rungia Klossii) Asal Distrik Mapia Kabupaten Dogiyai

The objective of this research is to identify the farming systems and the utilization of sayur hitam (Rungia klossii) by the Mee tribe in the Regency of Dogiyai as well as to provide information about the nutrients in the R. klossii. Descriptive method with direct observation is used in the field to examine the farming system and crop nutrient content. Analytical procedures were implemented using Gravimetry and atomic absorption spectrophotometry. The analysis were conducted in the Laboratory of Chemistry, Faculty of Science, University of Papua on April 2016. The variables observed by those methods include the identification of farming systems and the crop nutrient content in the leaves. Farming systems applied by the community to cultivate Rungia klosii is a mixed farming systems based on local knowledge. Based on the analysis of the nutrient content of Rungia klossii in terms of water content, oil content of fat, iron levels, manganese content, the levels of calcium and magnesium levels, the magnesium levels in Rungia klosii is 272.0892 mg/L which is the highest.

Large-Scale Use of Pond Ash for Reclamation of Waste/Alkaline Land for Agriculture

In India, thermal power plants presently produce 118×106 t of coal ash per annum, which is projected to exceed 440×106 t per annum by 2030. This huge quantity of coal ash not only has tremendous environmental concerns but also occupies large areas of land for its dumping, requiring urgent and appropriate measures for its safe disposal and gainful utilization on sustainable basis. In addition, reclamation of a vast area of wasteland for agriculture and forestry is another challenge for the country’s fast-growing population. The Central Institute of Mining and Fuel Research has carried out a detailed study on the bulk utilization of coal ash in agriculture and forestry sectors under different agroclimatic conditions and soil types for last two decades. The demonstration studies for the popularization purpose were carried out in the waste/alkaline lands of farmers’ fields and the results of such investigations are reported in this paper. The productivity of various crops grown in the ash-amended treatments substantially showed increased yield (20–45%) over control, with noticeable increase in the nutrient content of crop produce, early maturity of the crops grown, and improvement in the nutrient status/biological activity of the soil.

Comparison of nutritional quality of the crops grown in an organic and conventional fertilized soil

Organic farming is growing rapidly in its potential for producing healthy foods and has been adopted in a wide range of climate and soil types. The perception among consumers is that organically produced crops possess higher nutritional quality. However, there are many factors that can affect the nutritional quality of crops, and few studies have been able to account for these differences. A comparative long-term study of organic versus mineral fertilisation has been conducted for nine years in a calcareous loamy soil classified as Xerofluvent in the Guadalquivir River Valley, near Seville, Spain. The macronutrient concentration, dry matter and nitrate content in the edible part of the plants over the last five years of the experiment were examined. We found that the nitrate concentration in the edible parts was significantly lower in crops grown in organically fertilised plots. We also found a tendency for lower N and higher P content in organic crops cultivated in same crop cycle. However, the results also showed variability in the nutritional parameters for the same crop but cultivated in different years. We conclude that it is not possible to assert a higher nutritional quality of organic crops according only to the criteria of fertiliser type; other factors, such as fertiliser characteristics and management in each particular crop cycle, exert a higher influence on the nutrient content of crops.

Effect of long-term potassium application on irrigated soil potassium and on the yield and nutrient of crops

通过在宁夏灌淤土区长达14年的连续施钾和小麦秸秆还田试验, 研究钾素投入对作物产量、养分和土壤钾素状况的影响。结果表明：小麦秸秆还田和长期施用钾肥均可不同程度提高小麦和玉米的经济产量, 其中施钾年平均增产小麦244 kg·hm^-2, 玉米397 kg·hm^-2, 处理之间产量表现为氮磷钾肥配合秸秆还田>施用氮磷钾肥>氮磷肥配合秸秆还田>只施用氮磷肥。定位后8~10年施钾肥开始显著有效, 玉米显效时间早于小麦；秸秆还田和钾肥的投入均可提高籽粒和秸秆的钾素吸收量, 秸秆含钾丰富, 籽粒钾含量仅占植株钾总量的13%~17%；施用钾肥可提高作物籽粒大中微量元素含量而降低秸秆中、微量元素含量, 促进籽粒对大部分元素的吸收；长期不施钾肥处理(NP和NP+St)0~20 cm土层土壤速效钾和缓效钾含量较定位开始时下降; 所有处理土壤全钾含量均表现下降, 下降幅度为0.8~1.2 g·kg^-1。

Cover Crop Nutrient and Biomass Assessment System Using Portable Hyperspectral Camera and Laser Distance Sensor

This study evaluated the potential of portable spectral camera techniques for measuring cover crop chemical composition in different growth stages. A height measurement system was also developed using a laser distance sensor to predict cover crop biomass. PLS (Partial Least Squares) regression was used to evaluate the relationship between cover crop nutrient content and spectral data. The study revealed that a partial cross-sectional area of canopy had a slightly higher correlation with the cover crop biomass than that of the canopy height. High correlations were observed between the predicted and observed accumulation of N (R2 = 0.8698), Ca (R2 = 0.8512), Mg (R2 = 0.8415) and K (R2 = 0.9451). This method can be used to obtain information on cover crop nutrient accumulation without disturbing cover crop growth.

Compost, Manure and Synthetic Fertilizer Influences Crop Yields, Soil Properties, Nitrate Leaching and Crop Nutrient Content

From 1993 to 2001, a maize-vegetable-wheat rotation was compared using either 1) composts, 2) manure, or 3) synthetic fertilizer for nitrogen nutrient input. From 1993 to 1998, red clover (Trifolium pratense L.) and crimson clover (Trifolium incarnatum L.) were used as an annual winter legume cover crop prior to maize production. From 1999 to 2001, hairy vetch (Vicia villosa Roth.) served as the legume green manure nitrogen (N) source for maize. In this rotation, wheat depended entirely on residual N that remained in the soil after maize and vegetable (pepper and potato) production. Vegetables received either compost, manure, or fertilizer N inputs. Raw dairy manure stimulated the highest overall maize yields of 7,395 kg/ha (approximately 140 bushels per acre). This exceeded the Berks County mean yield of about 107 bushels per acre from 1994 to 2001. When hairy vetch replaced clover as the winter green manure cover crop, maize yields rose in three of the four treatments (approximately 500-1,300 kg/ha, or 10-24 bu/a). Hairy vetch cover cropping also resulted in a 9-25 % increase in wheat yields in the compost treatments compared to clover cover cropping. Hairy vetch cover crops increased both maize and wheat grain protein contents about 16 to 20% compared to the clover cover crop. Compost was superior to conventional synthetic fertilizer and raw dairy manure in 1) building soil nutrient levels, 2) providing residual nutrient support to wheat production, and 3) reducing nutrient losses to ground and surface waters. After 9 years, soil carbon (C) and soil N remained unchanged or declined slightly in the synthetic fertilizer treatment, but increased with use of compost amendments by 16-27% for C and by 13-16% for N. However, with hairy vetch cover crops, N leaching increased 4 times when compared to clover cover crops. September was the highest month for nitrate leaching, combining high rainfall with a lack of active cash crop or cover crop growth to use residual N. Broiler litter leaf compost (BLLC) showed the lowest nitrate leaching of all the nutrient amendments tested (P= 0.05).

Biofortified and bioavailable: The gold standard for plant-based diets

Much of the world's population relies on a few staple foods (rice, maize, wheat, and cassava) that are poor sources of essential nutrients. Biofortification, the process of enriching the nutrient content of crops as they grow, provides a sustainable solution to malnutrition worldwide, because other methods, such as diversifying people's diets or providing dietary supplements, have proved impractical, especially in developing countries (1). One of the first biofortified crops was golden rice, which was engineered to produce beta-carotene or provitamin A in the edible portion of the grain (2). Since then, there have been similar successes with other crops, giving us a variety of carotenoid-enriched foods (1) as well as crops enriched with other micronutrients such as vitamin E (3) and folate (4). However, in each of these cases, assumptions about whether the nutrients are bioavailable—i.e., whether the nutrients can be readily absorbed by humans—remain untested. In a recent issue of PNAS, Morris et al. (5), using feeding studies with both mice and humans, report that carrots genetically engineered to accumulate twice as much calcium as control carrots are indeed a good source of this essential nutrient, resulting in a ≈50% increase in calcium absorption.

Nutrition and growth of wheat–sorghum rotation in soils amended with leaf litter of trees before planting of wheat

Nutrient release from plant residues can be manipulated as per crop demand through several approaches. A pot study was conducted to study the influence of incorporation of leaf litter of poplar (Populus deltoides), eucalypt (Eucalyptus hybrid) and dek (Melia azedarach) inoculated with cellulolytic fungus culture (Aspergillus awamori) on the nutrition and biomass of wheat (Triticum aestivum, cv. PBW 343) in loamy sand and sandy loam soils. The residual effect of leaf litter after wheat harvest was studied on sorghum (Sorghum bicolor, cv. Punjab Sudax Chari 1). The treatments consisted of a control (no leaf litter) and three uninoculated as well as inoculated leaf litter levels of tree species–0.15%, 0.30% and 0.45% (w/w, dry weight basis). A uniform dose of N, P and K @ 50, 11 and 10 mg kg−1 soil, respectively from inorganic fertilizers was applied to all the treated pots. Straw and grain yield, and nutrient content of wheat increased with increasing level of uninoculated or inoculated leaf litter in both the soils. The inoculated leaf litter augmented the yield and nutrient content of crop significantly (P < 0.05) as compared to the corresponding uninoculated treatments. Poplar and dek leaf litter produced higher wheat yield, plant nutrient content and available nutrients in soil after wheat harvest than eucalypt leaf litter. Dry matter yield of sorghum raised on residual fertility increased significantly with increasing levels of leaf litter application. The comparative responses in yield and nutrient content of crops were higher in loamy sand than in the sandy loam soil. The study shows the beneficial influence of use of cellulolytic microorganisms on enhancement in decomposition and nutrient release from litterfall of tree species.

Efficacy of Bacterial or Fungal Soil Amendments on Vegetables Following Peanut

Amendment of soil with microorganisms during the growth cycle of one crop may affect development of succeeding crops. Species of Rhizobium bacteria or abuscular-mycorrhizal fungi were added alone to, or in combination with, potting soil in pots in a greenhouse. Controls were no amendments. Seed of peanut (Arachis hypogaea L.) were planted and two levels of a combination NPK fertilizer, the recommended and one-fourth the recommended rate, were applied. After harvest of peanut and remoistening of soil, seed of the bell pepper (Capsicum annuum L.) or navy bean (Phaseolus vulgaris L.) were sown into the same planting medium in pots without additional inoculation with microbes. Dry weights of above-ground vegetative and edible portions of crops were determined. Inoculum type only affected peanut top and total dry weights. The recommended fertilizer level did not affect peanut yield but did cause improvement in bell pepper and navy bean yield over that of the deficient fertilizer rate. In field experiments, peanut was planted into soil receiving Rhizobium spp. bacteria, or arbuscular-mycorrhizal fungi alone or in combination. Controls consisted of no amendment. Only the recommended fertilizer rate was used. In the next 2 years, bell pepper or navy bean were established in plots without use of additional microbial amendment. Yields and nutrient contents of crops were determined. Type of inoculum did not affect yield or nutrient content in any crop. Bell pepper marketable yield was unaffected by year, and navy bean seed yield was higher in 2004 than in 2005. In both years, navy bean yields were below U.S. averages. Concentrations of most nutrients in edible portions of bell pepper and navy bean were lower in 2004 than in 2005. Results of the field trials were generally similar to those of greenhouse studies. Use of inocula did not provide substantial benefits to yield or nutrient content of peanut or vegetable crops that followed.

Management of mine spoil for crop productivity with lignite fly ash and biological amendments

Long-term field trials using lignite fly ash (LFA) were carried out in rice crops during the period 1996–2000 at Mine I, Neyveli Lignite Corporation, Tamil Nadu. LFA, being alkaline and endowed with an excellent pozzolanic nature, silt loam texture, and plant nutrients, has the potential to improve the texture, fertility, and crop productivity of mine spoil. The rice crops were the first, third, fifth, and sixth crops in rotation. The other crops, such as green gram (second) and sun hemp (fourth), were grown as green manure. For experimental trials, LFA was applied at various dosages (0, 5, 10, 20, 50, 100, and 200 t/ha), with and without press mud (10 t/ha), before cultivation of the first crop. Repeat applications of LFA were made at the same dosages in treatments of up to 50 t/ha (with and without press mud) before cultivation of the third and fifth crops. Press mud, a lightweight organic waste product from the sugar industry, was used as an organic amendment and source of plant nutrients. Also, a recommended dosage of chemical fertilizer, along with gypsum, humic acid, and biofertilizer as supplementing agents, was applied in all the treatments, including control. With one-time and repeat applications of LFA, from 5 to 20 t/ha (with and without press mud), the crop yield (grain and straw) increased significantly ( p<0.05), in the range from 3.0 to 42.0% over the corresponding control. The maximum yield was obtained with repeat applications of 20 t/ha of LFA with press mud in the third crop. The press mud enhanced the yield in the range of 1.5–10.2% with various dosages of LFA. The optimum dosage of LFA was 20 t/ha for both one-time and repeat applications. Repeat applications of LFA at lower dosages of up to 20 t/ha were more effective in increasing the yield than the corresponding one-time applications of up to 20 t/ha and repeat applications at 50 t/ha. One-time and repeat applications of LFA of up to 20 t/ha (with and without press mud), apart from increasing the yield, evinced improvement in the texture and fertility of mine spoil and the nutrient content of crop produce. Furthermore, some increase in the content of trace and heavy metals and the level of γ-emitters in the mine spoil and crop produce was observed, but well within the permissible limits. The residual effect of LFA on succeeding crops was also encouraging in terms of eco-friendliness. Beyond 20 t/ha of LFA, the crop yield decreased significantly ( p<0.05), as a result of the formation of hardpan in the mine spoil and possibly the higher concentration of soluble salts in the LFA. However, the adverse effects of soluble salts were annulled progressively during the cultivation of succeeding crops. A plausible mechanism for the improved fertility of mine spoil and the carryover or uptake of toxic trace and heavy metals and γ-emitters in mine spoil and crop produce is also discussed.