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EM and VAM technology in Pakistan. Effect of co-inoculation of effective microorganisms (EM) and VA mycorrhiza on plant growth and nutrient uptake in chickpea (Cicer arietinum L.)
... In our earlier studies (Javaid et al., 1999; Bajwa et al., 1999) similar observations have been reported in Trifolium alexandrianum and Vigna radiata. However, in contrast, enhanced VAM colonization due to EM with a parallel increase in crop growth has been reported in maize (Bajwa & Jilani, 1994), chickpea (Bajwa et al., 1998) and sunflower (Javaid et al., 1999). Further studies regarding the effect of EM on VAM colonization, nodulation and crop growth with respect to history of EM application, organic amendments and test species is needed before any conclusion can be drawn. ...
To assess the comparative economic returns of various commercial herbicides on the transplanted rice, the experiment data generated at Ayub Agri. Research Institute Faisalabad during 1996-97 and 1997-98 was analyzed using partial budgeting technique. The results of the study showed that the herbicide Machete @ 2.25 L ha-1 was most appropriate in rice production, as it gives highest returns among the The control of weeds in rice production is a serious problem in Pakistan's Agriculture. Weeds result in reduction of yield, increasing the cost of production and lowering the quality of products. The use of herbicides in Pakistan is just in the introductory stage and it is important that farmers in the use of herbicides behave rationally. However, economic conditions of farmers and the expected returns govern the magnitude of herbicide use. It is, therefore, essential that the use of herbicide for weed control in rice production increases return of the farmers. The present study aims to assess gross and met benefits from the use of various herbicides used in rice production and to suggest an appropriate herbicide (s) and their levels of use at which increase in rice production is effective. MATERIALS AND METHODS applied); T2 = Machete @ 2.0 L ha-1;.T3 = Machete @ 2.25 L ha-1; T4 = Machete @ 2.50 L ha-1; T5 = Saturn @ 1 L ha-1; T6 = Saturn @ 1.2 L ha-1; T7 = Saturn @ 1.5 L ha-1 T 2, T3 and T4 indicate various doses of herbicide applied on rice. Similarly T5, T6 and T7 show the doses of Saturn herbicide applied on the crop. Partial budgeting technique was used for the analysis of data. The technique involved selecting of those costs that vary with particular treatment being analyzed and the net benefits of each treatment. The following sequence of steps was followed during the analysis of data. 1. Average yield of rice was calculated for each treatment.
... Javaid et al. (1995) showed that application of beneficial microorganisms in unsterilized field soil enhanced mycorrhizal colonization in the roots of pea, resulting in increased growth, yield, nodulation, and nitrogen nutrition in host plant. Similarly, Bajwa et al. (1998b) observed a significant increase in root and shoot growth, and shoot P and N content in chickpea due to co-inoculation of beneficial microorganisms and mycorrhiza. Beneficial microorganisms application also favored mycorrhizal development in root cortex of host chickpea plants. ...
There was a desperate need for food to recover the economy of the 1950s and 1960s. Farmers all over the world were advised to rely on intensive production methods and synthetic pesticide inputs to increase the productivity. No doubt, these chemical-based agricultural practices substantially increased crop yield. However, indiscriminate use of agrochemicals have contributed significantly to the environmental pollution and adversely affected human and animal health. In addition, the increasing cost of these agrochemicals has continued to lower the farmer’s net cash return. The global use of synthetic pesticides at the start of this millennium exceeded 2.5 million tons per year. A growing worldwide concern for these problems has motivated researchers, administrators, and farmers to seek alternatives to chemical-based, conventional agriculture. One such product is effective microorganisms (EM) developed by Japanese scientists. Effective microorganisms are a mixed culture of beneficial and naturally occurring microorganisms, such as species of photosynthetic bacteria (Rhodopseudomonas palustris and Rhodobacter sphaeroides), lactobacilli (Lactobacillus plantarum, L. casei, and Streptococcus lactis), yeasts (Saccharomyces spp.), and Actinomycetes (Streptomyces spp.). These beneficial microorganisms improve crop growth and yield by increasing photosynthesis, producing bioactive substances such as hormones and enzymes, controlling soil diseases, and accelerating decomposition of lignin materials in the soil. Experiments conducted on various agricultural crops in different parts of the world have shown good prospects for the practical application of these beneficial microorganisms in improving crop yield and soil fertility. Application of beneficial microorganisms generally improves soil physical and chemical properties and favors the growth and efficiency of symbiotic microorganisms such as nitrogen fixing rhizobia and arbuscular mycorrhizal (AM) fungi. Nonetheless experiences of some researchers revealed that the effect of these microorganisms on crop growth and yield was usually not evident or even negative in the first test crop. However, this adverse effect can be overcome through repeated applications of these microorganisms. Research on these microorganisms has shown that crop yields tend to increase gradually as subsequent crops are grown. Foliar application of beneficial microorganisms avoids many of the biotic and abiotic factors and constraints of the soil environment, and thus increases the crop growth and yield significantly. Application of beneficial microorganisms also reduces seed bank of weeds in agricultural soils by enhancing the rate of weed seeds germination. There are reports of management of various fungal and bacterial pathogens as well as insect pests due to application of beneficial microorganisms. These microorganisms have shown a great promise in dairy wastewater treatment. They can reduce NH3 concentration in poultry manure up to 70% possibly by transforming NH
4+ to NO
3−. Research conducted so far concludes that benefits of beneficial microorganisms can be best exploited through their repeated applications for few years in combination with organic amendments and applying them as foliar spray. Integrated use of organic matter plus beneficial microorganisms with half mineral NPK can yield equivalent to that of full recommended NPK fertilizers dose. Beneficial microorganisms can also be used for wastewater treatment, pest and disease management, and to reduce the abiotic stresses on crop growth and yield.
Cover crops can reduce the dependence of farmers on agrochemicals while enhancing overall agrosystem’s performance. However,
the inherent complexity of cover-crop-based systems hampers their adoption by conventional farmers. Therefore, special management
skills and alternative research and technology transfer approaches may be required to facilitate their adoptive use by conventional
farmers. We propose that development and adoption of suitable cover-crop-based production systems may require the use of an
“innovation framework” that includes (1) identification of system constraints, (2) analysis of system behavior, (3) exploration
of alternative systems, and (4) system design and selection. We describe case studies from four regions of the Americas (Florida,
USA; Paraná and Santa Catarina, Brazil; and Canelones, Uruguay) that illustrate the relationships between this innovation
framework and the development and adoption of cover-crop-based production systems. Where successful, development and adoption
of such systems appear to relate to a number of attributes including (1) active involvement by farmers in research and dissemination
programs; (2) integration of cover crops into production systems without net loss of land or labor resources; (3) informing
farmers of the (direct) benefits of cover crop use; (4) provision of multiple benefits by cover crops, (5) sufficient access
to information, inputs, and technologies required for cover crop use; and (6) provision of skills and experience necessary
to manage cover crops effectively. Where these attributes are absent and failure to innovate has prevented development and
adoption of cover-crop-based systems, policy initiatives to reward farmers for ecological services provided by cover crops
may be required.
KeywordsCover crops-green technologies-system analysis-innovation-adoption-sustainability-Americas-• green manure-• living mulch
Consumers are demanding more organic products, in part because of concerns over environmental issues in conventional agriculture.
Modern, high-input agriculture can cause groundwater contamination, soil erosion, and eutrophication of surface waters. It
may be possible to enhance natural nutrient cycling and reduce our dependence on inorganic fertilizers in cropping systems.
To do so, we have to manage our cropping systems to encourage diverse soil microbial communities and arbuscular mycorrhizal
fungi. This chapter reviews the impacts of cropping management practices on soil microbial diversity and arbuscular mycorrhizal
communities. Systems that have reduced tillage, diverse crop rotations or intercrops, low applications of inorganic fertilizers
and pesticides, and some organic fertility inputs tend to encourage a large and diverse microbial community with mycorrhizal
fungi. Organic systems should strive for minimum tillage and the avoidance of bare soil fallow in rotation. Well-managed conventional
systems with minimum tillage and inorganic crop inputs can be as effective as organic systems in encouraging soil biological
fertility. Both organic and conventional cropping systems should incorporate intercrops into their systems to encourage diversity
within the soil system.
KeywordsDiversity-arbuscular mycorrhizal fungi-organic management-conventional management-tillage-crop rotation-fertilizers and pesticides-organic farming-soil biodiversity-tillage-no till-crop rotation
Plants require inorganic nutrients in addition to carbon dioxide and water for growth and production. Nutrients are present
in soil, but get depleted unless supplied through fertilization. Soil feeding is the normal practice, but has limitations
with respect to its availability to the plants. The elements such as phosphorus, potassium, and most of the micronutrients
are fixed in the soil complex, while the more soluble nutrients such as nitrogen are easily leached down the soil. What is
lost through leaching reaches the aquifer and pollutes the groundwater. For instance nitrates and phosphates can be harmful
to humans. With increasing costs of fossil fuel, which provides the raw materials for fertilizer manufacture, there is a need
to find innovations in fertilizer usage techniques. Foliar application is one such technique. Here I review the extensive
work that has been carried out on the effectiveness of foliar-applied nutrients, the mechanisms of foliar absorption, and
transport. The leaf components such as the cuticular membranes, the trichomes, the cuticular pores, ectoteichodes, their properties,
and their role in the nutrient transport into the plant leaf are reviewed. Cuticles are permeable to nutrient ions present
in aqueous forms and have distinct structures like pores. But it is not known if these pores facilitate easy entry into the
leaf cells. The trichomes increase the amount transported into the leaf by providing more area for absorption. The cuticles
have two types of lipophilic substances, the cutin and the cuticular wax, which influence the permeability of nutrient ions
to varying degrees. It is clear that nutrients reach the leaf cells, after penetrating the cuticle, and are further transported
to other parts through plasmadesmata. Some micronutrients are not as freely mobile as the major nutrient elements such as
N, P, or K. The age of the leaf and the pH of the spray liquid are important for foliar absorption. The absence of plasmadesmatic
connections between the guard cells and the epidermal cells is also important. One element Cl has been found to be transported
from the applied leaf to other parts rapidly, showing it is freely mobile. This should be true for many anions. The concept
of limiting factors and the law of the maximum proposed by Wallace group are useful in raising the yield plateau, and when
soil supply poses the “limiting” factor, foliar feeding will help increase the crop yield. Modern technique of sprinkler irrigation
system can be exploited to supply the nutrient elements in the irrigation water, which will be economical in foliar fertilization.
Foliar nutrition is very practical to correct micronutrient deficiencies, which are very important for maximizing the yield.
Crop breeders could also help evolve cultivars, which give good response to foliar feeding.
KeywordsCritical growth stage-cuticle-eutrophication-inorganic nutrients-leaf uptake-sprinkler irrigation
The urgency of the global food crisis, coupled with the environmental impact of global warming and fuel shortages, indicate that transgenic methods may be required to enhance food production and quality. Widely used chemical insecticides, such as phosphine and methyl bromide, are losing their utility either due to insect resistance or to the environmental damage they cause. It is most unlikely that traditional plant-breeding methods for generating insect resistance will deliver the crop improvements required in the available time frame. In this review, we discuss the application of transgenic avidin, a protein naturally occurring in egg-white, for the protection of rice, maize, potato and apple leaf from insect pests. Avidin binds the vitamin biotin with extraordinary affinity (10−15 M). Biotin is a water-soluble vitamin required for normal cellular metabolism and growth. The presence of avidin in the diet of insect pests is lethal since biotin is unavailable to them. The use of streptavidin, a bacterial homologue of avidin, is also described. We discuss the sub-cellular targeting of avidin expression in plants to avoid toxicity to the plant host and we describe the qualities of avidin which make it suitable for crop protection during cultivation and storage. Avidin is stable under normal conditions of crop storage but biodegradable and destroyed by cooking. These combined qualities make it an excellent choice for the protection of crops from insects. Finally, we discuss the modification of the avidin gene to allow expression in plants, the methods for transfection of the gene into plants, and the approaches used to quantify gene expression and avidin function in plant tissues. These methods include: polymerase chain reaction; enzyme-linked immmunosorbent assay; polyacrylamide gel-electrophoresis; fluorescence polarisation (FP); capillary electrophoresis; tissue-printing; square-wave voltammetry (SWV) and the measurement of larvae morbidity and mortality.
Soilborne pathogens are difficult to manage, especially since the use of methyl bromide has been phased out in most countries.
Resistance against many soilborne pathogens is hardly available and fungicides are effective only to a limited extent. In
organic agriculture, many problems related to soilborne pathogens are avoided by applying wide rotations, but still some polyphagous
soilborne pathogens can be highly problematic, especially since most chemical crop protectants are not allowed. In addition,
wide rotations are often economically unprofitable. Therefore, alternative practices to manage soilborne pathogens are needed.
In this review, the occurrence of soilborne pathogens in three types of cropping systems are evaluated: (i) continuous cultivation
of single crops in monoculture, (ii) crop rotation, and (iii) mixed cropping, i.e., cultivation of multiple crops in the same
field at the same time. Both continuous cropping and crop rotation have been investigated extensively. Therefore, in this
chapter we focus on mixed-cropping systems in relation to soilborne pathogens, their potential to suppress soilborne diseases,
and the mechanisms underlying disease suppression. In general, mixed cropping is practiced to optimize nutrient uptake, control
soil erosion, suppress the epidemic spread of airborne pathogens, and improve crop yields per unit of area. While mixed cropping
has received attention for its effects on airborne pests and pathogens, the effects on soilborne pathogens are poorly known.
In 30 out of 36 publications, mixed cropping showed a significant reduction in soilborne disease and in six, no or a positive
effect on disease incidence or severity was found. Diseases caused by splash-dispersed pathogens were less severe in mixed-cropping
systems in ten out of 15 studies. The magnitude of disease reduction in mixed compared to single crops varied, from a 63%
reduction to a 100% increase in disease. Host dilution appeared to be the most important mechanism of disease suppression
for both soilborne and splash-dispersed pathogens (12 and five cases, respectively). Although the use of mixed cropping for
soilborne disease suppression is still in its infancy, the wide range of biological effects and interactions observed holds
promise for further optimization and management of soilborne diseases, for example, by selecting plant species and cultivars
that provide an optimal combination of root architectures.
KeywordsMixed cropping-intercropping-soilborne pathogens-crop rotation-microclimate-monocropping-multiple cropping-disease management-allelopathy-ISR (induced systemic resistance)-SAR (systemic acquired resistance)-microbial antagonism
Organic farming is a sustainable agricultural system that respects and relies on natural ecological systems. Its principles
exclude the use of synthetic pesticides and fertilizers. Instead it is based on management practices that sustain soil quality
and health. Composting of organic residues and the use of compost in agriculture bring back plant nutrients and organic matter
to the soil that otherwise would be lost. Nevertheless, there are some potential risks associated with compost use, such as
the accumulation of heavy metals or organic pollutants, which must not be neglected. Some types of organic farms, such as
stockless farms or vegetable farms, have difficulties sustaining soil humus using only organic farming sources. For such farms,
using biowaste compost from separately collected organic household waste might be a solution, which in addition helps to close
nutrient and organic matter loops of the whole society. Here we compile information on beneficial effects and potential risks
associated with compost use and on crop yields and quality, with compost under an organic farming perspective. The most important
benefit of using compost is the increase in soil organic matter (SOM). Under temperate climate conditions, 6–7 t ha−1 year−1 (dry wt.) compost is sufficient to maintain the soil humus level of medium-textured soils; higher rates increase the soil
humus content. Regular compost addition enhances soil fauna and soil microbial biomass and stimulates enzyme activity, leading
to increased mineralization of organic matter and improved resistance against pests and diseases, both features essential
for organic farming. Through the significant increase in the soil’s content of organic carbon, compost fertilization may make
agricultural soil a carbon sink and thus contribute to the mitigation of the greenhouse effect. Phosphorus and potassium in
compost become nearly completely plant-available within a few years after compost application. The nitrogen-fertilizer value
of compost is lower. In the first years of compost application, N mineralization may vary from −15% to +15%. Nitrogen recovery
in the following years depends on the site- and cultivation-specific mineralization characteristics and will roughly be the
same as that of soil organic matter (SOM). Soil cation exchange capacity (CEC) increases with compost use, improving nutrient
availability. Moderate rates of compost of 6–7 t ha−1 year−1 dry wt. are sufficient to substitute regular soil liming. In the available micronutrient status of the soil, only minor changes
are to be expected with high-quality composts. Increasing soil organic matter exerts a substantial influence on soil structure,
improving soil physical characteristics such as aggregate stability, bulk density, porosity, available water capacity, and
infiltration. Increased available water capacity may protect crops against drought stress. Plant-disease suppression through
compost is well established in container systems. In field systems, the same processes involving the suppression of pathogens
by a highly active microflora supported by the supply of appropriate organic matter are likely at work. When using high-quality
composts, such as specified by the EU regulation 2092/91, the risk of heavy metal accumulation in the soil is very low. Nitrogen
mineralization from compost takes place relatively slowly and there are virtually no reports of uncontrollable N-leaching.
Concentrations of persistent organic pollutants such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls
(PCBs), or polychlorinated dibenzodioxins and dibenzofurans (PCDD/F) in high-quality composts usually approach the usual soil
background values. Also the overall hygiene and hygiene concerning plant diseases and weeds are not a problem if quality composts
produced in a monitored system are used. Most studies found positive yield effects of biowaste compost. However, the effect
of biowaste compost applied at moderate rates usually takes some years to develop. It depends on the factors determining nutrient
mineralization from soil and compost and also on crop-related factors such as the nutrient requirements and uptake dynamics
of the respective crop rotation. Crops with longer growth periods can make better use of compost. Many vegetable crops respond
favorably to compost fertilization, often immediately after the first application. Crop quality is usually not affected by
compost fertilization in cereals and slightly positively influenced in vegetable crops.
KeywordsSoil humus-nitrogen-phosphorus-potassium-soil structure-heavy metals-organic pollutants-yield-crop quality-compost-organic farming-Cd-Zn-Ni-Pb-Hg-Cu-Cr-PAH-dioxin-CEC-soil pH-soil N-nitrate, P, K-micronutrients-soil aggregate-soil water-plant disease-maize-wheat-barley-potato-tomato-broccoli-cabbage-cauliflower-cantaloupe-legume-onion
The sustainable use of nutrients in agricultural food production represents a major emphasis for international research, and
evidence that clearly demonstrates the imbalance between nutrient inputs and outputs exists. Nutrient surpluses exist and
are most commonly associated with intensive livestock production and present a particular range of environmentally related
issues. Nutrient deficiency can also develop, and organically managed systems highlight the difficulties that are involved
in maintaining agronomically acceptable concentrations of soil phosphorus (P). A restricted range of P-containing sources,
often having poor solubility, exacerbate these difficulties, and obvious benefits would arise if the availability could be
“naturally” enhanced. Slow rates of phosphate rock (PR) solubilization under prevailing soil conditions reduce the general
agronomic usefulness and potential benefits that any direct applications might provide. Being able to improve rates of dissolution
through some control of the solubilization process would offer widespread potential advantages, particularly with respect
to better matching patterns of P supply with crop demand. A variety of pre and postapplication opportunities exist to improve
the solubility of rock phosphate. Some of these have particular relevance to organic agriculture where phosphate rock represents
an important and acceptable “external” source of P. A range of post-application, farm management practices that include green
manures and rotations using crops with favorable traits that improve P utilization have been successfully employed. Here,
we emphazise pre-application techniques, especially the co-composting of phosphate rock with various organic by-product materials
that include livestock manures and residual vegetable matter. A range of laboratory incubations have demonstrated the underlying
mechanisms involved with solubilization. The significance of microbially induced production of organic acids and acidity during
composting is particularly important in this respect. While co-composting with phosphate rock offers a great potential that
could be developed for use at the individual farm scale, the key controlling factors and underlying mechanisms are far from
being fully understood. A possible time sequence of reactions that might be envisaged include an initial production of protons
and organic acids leading to the mineralogical dissolution and release of Ca and P, followed finally by an extended period
during aging of the compost where secondary reactions appear to influence the form of P. The consequences of composting conditions
and individual processes on immediate and longer-term bioavailability of P once field applied are still poorly defined.
KeywordsPhosphate rock-composting-sustainability-nutrient use efficiency
Within the last 2 decades the transition in livestock production technology and intensity has resulted in an increase in annual
livestock production and a drastic decrease in the number of livestock operations. Consequently, the susceptibility of current
livestock operations to experience manure spills is far greater relative to livestock farms 20 years ago, due to increased
herd size per farm. Therefore, manure spills in agricultural communities have become a pervasive issue and have led to the
catastrophic contributions of nutrients and pathogens to surface and groundwaters, human health issues, and large fish kills.
Furthermore, the current remediation methods for manure spills that reach surface waters focus on mitigating contaminants
in the water column and give no attention to the manure-exposed ditch sediments that remain in the fluvial system and continue
to impair the water column. Therefore, this chapter addresses the causes, environmental impacts, and current and alternative
remediation methods for manure spills in agricultural streams. Geographic data suggest that the location of animal-feeding
operations and the occurrence of manure spills were highly correlated with the location of tile-drained agriculture fields.
In addition, at least 14% of reported manure spills were separately attributed to the failure in waste storage equipment and
over-application of manure in the states of Iowa and Ontario, Canada. Evaluations of the downstream impacts of manure spills
have reported ammonia, total phosphorus, and total N concentrations that were at least 28 times the average upstream concentrations
before the spill occurred. Studies have also determined that the current manure spill remediation method results in soluble
phosphorus and nitrogen concentrations significantly greater than the Environmental Protection Agency total phosphorus nutrient
critical limit, 24 h after the plume of the spill has passed. However, supplemental treatment of manure exposed sediments
resulted in at least a 50% decrease in the soluble phosphorus concentrations which was in compliance with the phosphorus nutrient
criteria.
KeywordsManure spills-manure spill remediation methods-alum-ammonium-phosphorus-sediments
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