Allelopathy as a Tool in the Management of Biotic Resources in Agroecosystems

Sorghum species are well known for allelopathic potential toward weeds and other crops. Sorghum above-ground residues mediate allelopathic activity through production and release of many allelochemicals including phenolic acids. Information is limited on selection of grain sorghum hybrids with high allelopathic potential and assessment of sorghum residue phenolic activity in soil under field conditions. This study was carried out to investigate several grain sorghum hybrids for allelopathic potential for suppressing weed growth in the field in the subsequent growing season; and to investigate the involvement of phenolic substances released into soil on the establishment of weeds. The weed seedbank was affected by environmental conditions that led to different weed densities subjected to suppression by residues in soil. Differential allelopathy was identified among the sorghum hybrids suggesting that improved selection may increase production and release of allelochemicals in new hybrids to control weeds inexpensively, easily, and environmentally friendly. Tillage type (till vs no-till) had variable effects on weed suppression. Soil type, environment, sorghum hybrid traits and cultural practices complicate the use of allelopathy in weed control and benefits gained from this potentially environment friendly weed control practice. Well-planned management will be required to successfully integrate allelopathic crops into sustainable crop production.

One of the most serious issues is biotic stress in plants produced by insect pests, which results in production losses. Synthetic pesticides continue to play an important role in crop protection. Yet, the environmental consequences and health risks caused by excessive or improper use of synthetic pesticides compelled authorities to ban some dangerous ones. As a result, there is an urgent need for unique and alternative insect pest management strategies. Allelopathy is a naturally occurring ecological phenomenon of organism interaction that can be used to manage weeds, insect pests, and illnesses in field crops. Allelopathy can be utilized in field crops after rotation, using cover crops, mulching, crop smothering, and plant extracts for natural pest management. Allelochemicals in soil are adsorbed on soil solids and decomposed during soil movement by chemical and biological reactions. Its behavior is influenced by soil characteristics such as soil texture, organic and inorganic matter, moisture, and organisms, all of which have an impact on phytotoxic activity in soil. Although allelochemicals are produced throughout the plant, root exudation is the principal source of chemical release into the soil environment. Therefore, this review will focus on the role of insect-pest management, factors affecting production and release of allelochemicals, their activity and limitations in insect-pest management.

This subject is reviewed under the following headings: pests and diseases in organic versus conventional agriculture; pest and disease management in organic versus conventional agriculture, including prevention of colonization or establishment of pests and pathogens in organic agriculture, regulation of established pests and pathogens in organic agriculture, host plant resistance, community resistance - vegetation, community resistance - pathogens and herbivores, community resistance - biological control, curative control; and pest and disease management case studies in organic versus conventional agriculture. Future research directions are also discussed.

The European Union (EU) aims to increase the adoption of organic farming as part of its Farm to Fork Strategy. However, farmers face uncertain adoption outcomes linked with crop yields, production costs, labour requirements and ultimately farm income. Yet, comprehensive large-scale empirical evidence on the economics of organic crop farming in the EU is currently lacking. Therefore, this study assesses the economic implications of organic farming adoption in the EU using methods for treatment effect estimation in combination with a large-scale cross-country dataset. It consists of 151,560 non-organic and 10,531 organic farms from the European Farm Accountancy Data Network, covering seven different crop production farm types, 16 EU countries and 7 years. Our analysis specifically focuses on input costs (crop protection, fertiliser, total crop specific costs), as well as labour input (including contract work costs, and total and family labour inputs) and gross farm income on a per hectare basis. We find that organic farming is associated with significantly lower crop protection and fertiliser expenditures as well as total crop specific costs across all farming types, while contract work costs vary across farming types. We find only minor differences in farm-level labour inputs between organic and non-organic farms. Farm income is smaller for organic farms without subsidies but higher when accounting for subsidies. However, effects are highly heterogeneous across farm types and across space. Our study contributes to a better understanding of the economic implications of organic farming expansion within the EU. These insights can inform both practitioners and policy-makers, facilitating the achievement of regional organic farming targets.

Back to Basics: Breeding plants for organic agriculture

Conventional agricultural systems have become more intensive and pesticide-dependent over the last few decades. The contamination of the environment by pesticides, the use of mineral fertilisers, and habitat loss in many agroecosystems have led to a drastic decrease in plant and animal biodiversity. Ecosystem services provided by functional biodiversity (e.g., pollination, biological pest control) have also been negatively impacted. Conservation biocontrol aims to preserve and promote natural enemies to enhance pest control, avoid pest outbreaks and reduce pesticide reliance. However, despite a consensus on the main underlying principles, intentional practical applications are still rare. It is assumed that the diversity of habitats and resources in agroecosystems enhances the diversity and/or effectiveness of the natural enemies of pests. In this article, we argue that organic farming (OF) provides a promising framework for increasing conservation biocontrol at field and farm scales in agricultural landscapes. We looked at most of the commonly used OF practices at different spatio-temporal scales and discussed their effects on pest populations, natural enemy communities and biocontrol in agroecosystems. Several OF management practices such as crop diversification, use of organic fertilisers, diversification of resource plants at the field or landscape scales and land-use management are examined in our review. We particularly focused on possible strategies to enhance pest control measures in two case studies (i.e., orchard and annual crops) and discussed how and at which scales such strategies should be implemented. In the end, we identified knowledge gaps and bottlenecks that, if resolved, would help to enhance conservation biocontrol and applications in OF systems that aim to maximise both bottom-up (through plants) and top-down (through natural enemies) processes.

The recent intensification of the arable landscape by modern agriculture has had negative effects on biodiversity. Organic farming has been introduced to mitigate negative effects, but is organic farming beneficial to biodiversity? In this review, we summarize recent research on the effects of organic farming on arable biodiversity of plants, arthropods, soil biota, birds, and mammals. The ecosystem services of pollination, biological control, seed predation, and decomposition are also included in this review. So far, organic farming seems to enhance the species richness and abundance of many common taxa, but its effects are often species specific and trait or context dependant. The landscape surrounding the focal field or farm also seems to be important. Landscape either enhances or reduces the positive effects of organic farming or acts via interactions where the surrounding landscape affects biodiversity or ecosystem services differently on organic and conventional farms. Finally, we discuss some of the potential mechanisms behind these results and how organic farming may develop in the future to increase its potential for sustaining biodiversity and associated ecosystem services.

Regenerative agriculture aims to restore soil health, enhance biodiversity, and ensure long-term sustainability of farming systems. Organic and natural farming practices play a pivotal role in achieving these goals by reducing dependency on chemical inputs, improving soil fertility, and promoting ecological balance. Natural farming, a regenerative agriculture is advocated and promoted worldwide to produce safe and quality produce and to live in harmony with nature. It is “Chemical free farming” or “do-nothing farming” is a sustainable farming approach that aims to work with nature instead of trying to change it. Natural farming, exemplified by Zero Budget Natural Farming (ZBNF), goes even further by minimizing external inputs altogether. It relies on indigenous methods like Jeevamrith and Beejamruth to nurture soil health and control pests naturally. The challenges in modern agriculture, including persistent hunger and malnutrition despite significant increases in production due to the Green Revolution. There are several negative impacts of chemical-based agriculture on soil health, environmental health and human health, particularly in countries like India with a large agricultural population. To address these issues, many are turning to alternative farming methods, such as organic and natural farming. Organic farming, rooted in traditional practices, aims to preserve soil health and produce food sustainably.This paper discusses the interconnection between organic and natural farming with regenerative agriculture, focusing on their impact on soil health, biodiversity, and sustainability. The research explores the benefits, challenges, and future prospects of integrating these systems to enhance agricultural resilience and productivity in a sustainable manner.

Organic farming promotes sustainable agriculture development by controlling our environment and providing food for future generations, in addition to meeting the needs of the present generation in an eco-friendly manner. Essentially, organic farming produces high-quality food without harming the environment or the health and efficiency of the soil. For a significant portion of the Indian population, organic farming also contributes to the production of more food. Several pesticides, fertilizers, and synthetic compounds are used in modern agriculture, which has a negative effect on soil health, poses a risk to water, and increases toxic residues in the food chain and animal feed industry, all of which contribute to an increase in health problems. The review paper's objectives are to determine which synthetic fertilizers and pesticides can be substituted with natural ones and to examine how organic farming could advance agricultural sustainability. . KEYWORDS :Bio-fertilizers, Bio-pesticides, Manure, Organic farming, Sustainable agriculture

Agricultural expansion has led to a significant loss of habitat and biodiversity in Ghana and throughout West Africa and the tropics generally. Most farmers adopt both organic and inorganic inputs to boost production, with the potential to slow agricultural expansion, but with relatively little consideration of related environmental impacts. In Ghana, where high-input modern farming is rapidly overtaking traditional organic agricultural practices, we examined five stakeholder groups in regard to their perceptions of the environmental, economic, and social costs and benefits of modern, mixed-input, and traditional farming systems. The stakeholder groups included farmers adopting different agricultural practices, as well as governmental and non-governmental natural resource managers. Our findings indicate that the overall perceived costs of modern farming, attributable to large quantities of inorganic inputs, are higher than the overall perceived benefits. Farmers are, however, still motivated to practice modern farming because of perceived higher returns on investment, regardless of environmental impacts, which they tend to discount. Traditional farmers do not use inorganic inputs and instead rely on swidden ‘slash-and-burn’ practices, resulting in declining productivity and soil fertility over time. Since traditional farmers are ultimately forced to encroach into nearby forests to maintain productivity, the perceived environmental sustainability of such farming systems is also limited. Mixed-input farming is not significantly different from modern farming with respect to its perceived environmental and economic traits, because it incorporates agro-chemicals alongside organic practices. Stakeholders’ perceptions and the apparent environmental outcomes of different farming systems suggest that reducing the use of inorganic inputs and promoting the adoption of organic inputs could minimise the negative impacts of agro-chemicals on the forest environment without necessarily compromising productivity. Campaigns to promote low-input or organic agriculture on environmental grounds in West Africa may falter if they fail to recognise farmers’ relatively favourable perceptions of the environmental implications of modern farming practices.

The agrochemical industry: its contribution to crop protection and environmental policy

In modern agriculture, organic farming has a part to play in conserving biodiversity. The aim of our study was to compare organic and conventional farms using appropriate agro-biodiversity indicators. Our survey in central Italy, where 33 farms were involved (18 organic and 15 conventional), shows that integration of biodiversity at the farm level is more likely to be achieved in organic farms than in conventional ones. We have used a wide range of indicators of cropping system biodiversity in order to be able to document elements of both structural and functional diversity with a value for agroecosystem sustainability. From our survey emerges a picture of a typical organic farm, where the average farm size is around 54 ha with diversified land use shared between agricultural (81.3%) and wood area (18.7%) and with integration between crop and animal husbandry.

Agronomic protocols (rotation, tillage, fertilization and crop protection) commonly used in organic and conventional crop production differ significantly and there is evidence that modern varieties developed for conventional high-input farming systems do not have the combination of traits required for optimum performance in organic farming systems. Specifically, there is evidence that prohibition on the use of water-soluble, mineral N, P and K fertilizers and synthetic pesticide inputs in organic farming results in a need to revise both breeding and selection protocols. For organic production systems, the focus needs to be on the following: (i) traits prioritized by organic farmers such as high nutrient use efficiency from organic fertilizer inputs, competitiveness against weeds, and pest and disease resistance, (ii) processing quality parameters defined by millers and bakers and (iii) nutritional quality parameters demanded by organic consumers. In this article, we review evidence from variety trials and factorial field experiments that (i) studied to what extent there is a need for organic farming focused breeding programs, (ii) investigated which traits/trait combinations should be targeted in these breeding programs and/or (iii) compared the performance of modern varieties developed for the conventional sector with traditional/older varieties favored by organic farmers and/or new varieties developed in organic farming focused breeding programs. Our review focuses on wheat because there have been organic and/or low-input farming focused wheat breeding programs for more than 20 years in Europe, which has allowed the performance of varieties/genotypes from organic/low-input and conventional farming focused breeding programs to be compared.

Plant protection is one of the major issues in organic farming. Organic crop protection (OCP) strategies often rely on a limited number of methods that provide only partial control of pests and that induce lower yields and economic performances. As a result, farmers hesitate to adopt these strategies and doubts are cast on the ability of organic agriculture to feed the world. This chapter questions how agroecological concepts may contribute to OCP, while taking the different alternative schemes already developed to manage, integrate and design crop protection strategies into account. As demonstrated by a bibliographic analysis, Integrated pest management (IPM) remains the leading paradigm in crop protection. It also provides its foundational basis, giving priority to bioecological processes and alternative techniques to reduce pesticide use. Beyond IPM, agroecology is characterised by a holistic approach and the importance given to the design of a “healthy” agroecosystem. In practice, all these concepts are subject to various interpretations, and organic farming includes a variety of practices, ranging from intensive input-substitution to a comprehensive integrated approach. This paper provides key elements for crop protection in OF on the basis of the adaptation of the agroecological crop protection approach. Based on a successful case study of fruit fly management in OF in Reunion Island (France), we highlight three major pillars to design pest management strategies: sanitation, habitat manipulation and conservation biological control. Finally, in the field of crop protection, this paper shows that organic farming can be both a prototype for designing innovations and a source of practices to be extended to other types of agroecosystems.

The origin and hazard of inputs to crop protection in organic farming systems: are they sustainable?