Organic Crop Production Practices: Management Techniques for Organic Farming provides an in-depth review of the practices used in growing organic crops. This book represents a current look at what we know about organic farming practices and systems, primarily from the United States perspective. The discussion begins with history and certification, ecological knowledge as the foundation for sustaining food systems, and biodiversity. The next chapters address approved amendments, crop rotation, cover cropping, intercropping, pest management, biorational and organic pesticides, seeds and planting stock, preventing contamination of organic crops, post-harvest handling and labeling and organic greenhouse production. Finally, a series of appendices provide numerous data relevant to growing organic crops. The information in this easy-to-use guide is distilled from a variety of sources, including scientific literature, extension publications, and grower experience and has the added value of numerous citations to more in-depth discussion on many topics. The book is thoughtfully organized presenting a seamless flow of topics within chapters making it easy to find specific information that interests the reader. No one concerned with the growing organic crops can afford to be without this book.
Organic agriculture is a system for crops that emphasizes environmental protection and the use of natural farming techniques. It is concerned not only with the end-product, but with the entire system used to produce and deliver the agricultural product. To this end, the entire farm cycle, from production and processing, to handling and delivery, excludes the use of artificial products such as genetically modified organisms (GMOs) and certain external agricultural inputs such as pesticides and synthetic fertilizers. Organic farmers rely instead on natural farming methods and modern scientific ecological knowledge in order to maximize the long-term health and productivity of the ecosystem, enhance the quality of the products, and protect the environment. Proponents of organic methods believe that it is a more sustainable and less damaging approach to the enrinoment.
Organic certification verifies that your farm or handling facility located anywhere in the world complies with the U.S. Department of Agriculture (USDA) organic regulations and allows you to sell, label, and represent your products as organic. These regulations describe the specific standards required for you to use the word “organic” or the USDA organic seal on food, feed, or fiber products. The USDA National Organic Program (NOP) administers these regulations, and validated by an accredited certifying agency. These agencies include private for profit and non-profit agencies, as well as public state-run certifying agencies. The standards are dynamic, and minor revisions are ongoing through a transparent process involving public notification, public comment, and federal rulemaking. All producers, handlers and processors who are certified are required to be compliant with the specific sections of the Final Rule that apply to their operation. Certified organic crop production is more than a list of acceptable and prohibited inputs or practices that can and can not be used; rather, it is a holistic approach to sustainable and healthy food production that enhances the well-being of the consumer and protects natural resources.
Substances that are used to produce and handle organic crops under the USDA’s National Organic Program (NOP) must be selected for compliance and used in the context of organic principles for farming and handling practices. Whether a substance is allowed or not depends on the context. Some types of materials are integral to maintaining an organic system. Others may be used only when cultural, biological, mechanical, or physical methods are insufficient. In fact, the NOP requires that management practices must be implemented, and found to be insufficient, prior to the use of any input including soil-building crop rotations; sanitation measures to remove disease vectors, weed seeds, and pest habitat; selection of site-suitable and resistant plant species and varieties; release of pest predators and parasites; development of habitat for pest predators; lures, traps and repellants; mulching, mowing, grazing, mechanical, flame, and/or hand weeding; and cultural practices to prevent weed, pest and disease problems. Certified organic producers and handlers must use only materials that are approved for use according to the standards to which they will be certified. Prior to using any material, certified operations must include in their Organic System Plan (OSP) a list of all materials they use or plan to use, which is approved by their organic certifier.
The foundation of organic farming lies in the management of preserving and improving soil structure, fertility, and organic matter content. Organic management techniques build organic matter and humus, protect the soil from erosion, reduce nutrient loss and maintain a diverse and healthy soil life. Organic farmers have different approaches to supplying crop needs compared to conventional farmers who provide fertility by numerous synthetic fertilizers. Organic farmers regenerate the fertility of the soil through renewable resources. In organic farming systems, the majority of nutrients are supplied from organic matter additions through crop rotation, green manures, and livestock manure and/or compost for short- and long-term fertility management. Increased organic matter makes nutrients more available, buffers and neutralizes soil pH, improves soil structure, raises biological activity, enhances water field capacity and drainage, and decreases erosion. Supplemental applications of organically approved amendments and fertilizers are also used such as mined minerals (e.g., rock phosphate, gypsum) or organically-based fertilizers such as fish emulsions and kelp in conjunction with a soil building program.
Organic soil amendments and fertilizers come from natural sources–plants, animals, and rocks. Soil amendments are used to condition or improve the soil. Most, but not all, soil amendments add some nutrients to the soil. An organic fertilizer is a natural soil amendment that adds plant nutrients to the soil, most often nitrogen, phosphorous, or potassium. Soil amendments and fertilizers that are in compliance with the national organic standards are available to complement other fertility practices. Animal- and plant-derived amendments, seaweed products, mined minerals, and microbial inoculants form the bulk of what is applied to organic fields to promote healthy plant growth. Most synthetic fertilizers are prohibited by the U.S. Department of Agriculture’s National Organic Program (NOP) rule [7 CFR 205.105(a)], with a few specific exceptions found on the National List [7 CFR 205.601(j)]. Note that the NOP forbids the use of human sewage sludge (biosolids) from a municipal wastewater treatment facility on an organic operation (§205.105 (g)). In addition, the use of raw or composted human waste generated on the farm may not comply with NOP requirements. Growers must manage plant and animal materials in a manner that does not contribute to the contamination of crops, soil, or water by pathogenic organisms (§205.203(c)). It is imperative that organic farmers check with their certification agencies before applying any materials. Certification may be revoked for up to three years if a material contaminated with prohibited materials is applied.
Soil building practices such as crop rotations, inter-cropping, symbiotic associations, cover crops, organic fertilizers, and minimum tillage are central to organic farming practices. These encourage soil fauna and flora, improving soil formation and structure and creating more stable systems. With the creation of the U.S. National Organic Program (NOP) in 2002, this philosophy became part of the federal laws regulating organic farming. Section 205.203 of the NOP requires that “the producer must select and implement tillage and cultivation practices that maintain or improve the physical, chemical, and biological condition of soil and minimize soil erosion.” Similarly, the International Federation of Organic Agriculture Movements standards also require minimum tillage and other practices to prevent soil erosion and degradation. Tillage is required (1) to eliminate perennial legumes or winter annual cover crops before planting annual crops, (2) to incorporate manure to avoid nitrogen (N) runoff and volatilization losses, and (3) to prepare a seedbed and control weeds. The dilemma for organic farmers is that these practices have negative consequences including loss of organic matter, increased soil strength, reduced infiltration rates, compaction, and increased erosion of the soil. However, organic farming systems have the potential to offset the negative influences of tillage on soil structure and organic matter with the importation of organic inputs such as manures and composts, recycling of on-farm organic matter, and well-designed crop rotations (including cover crops and perennial forages).
Cover crops are an integral part of organic production systems and one of the major tools that organic farmers. The purposes for cover cropping in organic systems do not differ from those in conventionally managed systems. However, the role of cover crops to support soil function takes on greater importance in organic systems because the use of synthetic chemical fertilizers and pesticides are generally not allowed. Cover crops may be used as green manures to increase soil organic matter and nitrogen availability, as catch crops to reduce leaching by holding nutrients in the soil rootzone, insectary mixes, mulches for providing soil cover to control weeds and reduce erosion, and as forage crops when used for grazing. Because of the important role of cover crops in providing these services, the use of cover crops in organic farming systems is mandated in the Soil Fertility and Crop Nutrient Management (§205.203) and Crop Rotation (§205.205) practice standards of the National Organic Program. Cover crops are oftern referred to as “green manures,” “catch crops,” or “living mulches.”
Crop rotation is a valuable management strategy for organic farming, which involves the cultivation of different crops in temporal succession on the same land. Usually the succeeding crop will be of a different variety and species than the previous crops. Crop rotations can be as simple as rotating between two crops and planting sequences in alternate years or they can be more complex and involve numerous crops over several years. Crop rotations can break host cycles for pests and diseases. Alternation of crops with different seasonal patterns and growth habits can also help to suppress weeds. Properly managed rotations can also increase microbiological diversity and activity; raise organic matter content; conserve soil; and enhance soil structure. Even simple rotations over a short time period significantly improved soil quality in controlled experiments. Rotations often include a “rest” period for individual fields, where grass or a “green manure” such as clover is planted for a season or more, before being grazed or ploughed into the soil to add fertility.
Intercropping is defined as the growth of more than one crop species or cultivar simultaneously in the same field during a growing season. It is the practical application of ecological principles such as diversity, crop interaction and other natural regulation mechanisms. Intercrops can be combinations of two or more species, including both annuals and perennials or a mixture. Intercropping has many advantages, mainly related to the complementary use of environmental resources by the component crops which results in increased and more stable yields, better nutrient recycling in the soil, better control of weeds, pests and diseases and an increased biodiversity. Cereals and legumes, both for forage and for grain, are the most common intercrops. However, despite its advantages, intercropping has traditionally been neglected on plant production systems in temperate agricultural ecosystems, due to its complexity and because of the difficulties for its management.
Animal manure is traditionally a key fertilizer in organic and sustainable soil management. Properly managed manure applications recycle nutrients to crops, improve soil quality, and protect water quality. Manure is most effectively used in combination with other sustainable practices. These include crop rotation, cover cropping, green manuring, liming, and the addition of other natural or biologically friendly fertilizers and amendments. In organic production, manure is commonly applied to the field in either a raw (fresh or dried) or composted state. The National Organic Program (NOP) Rule requires that manure either be composted or that the operator observes a minimum interval between the application of manure and harvest of crops for human consumption. The NOP Rule provides a strong incentive to use composted manure and places stringent restrictions on uncomposted manure
Composting is the decomposition of organic matter through a controlled microbiological process. Composting transforms raw organic materials (e.g., plant or animal materials) into a biologically stable, humic substance that makes excellent soil amendments. The use of compost has long been considered a defining feature of organic farming systems in building long-term soil fertility and tilth by feeding the soil with a variety of natural amendments. While fewer nutrients are immediately available for crop growth, compost’s real agronomic value lies in the gradual release of nutrients that are slowly converted from stable organic compounds into available inorganic nutrients. In addition to adding nutrients to the soil, compost can improve long-term soil health. Organic farmers are strongly encouraged to use compost because it reduces human, plant, and animal pathogens; destroys weed seeds; decomposes organic matter; and makes nutrients more available to plants.
Insect pest management presents a challenge to organic farmers. Insects are highly mobile and well adapted to farm production systems and insect pest control tactics. No single tactic, employed alone, is likely to give satisfactory control of chronic insect pests. Certified organic farmers can use a wide range of practices to create an integrated pest management approach that complies with the standards of the USDA’s National Organic Program (NOP). According to the organic standard, insect pest problems may be controlled through cultural, mechanical, or physical methods; augmentation or introduction of predators or parasites of the insect pest species; development of habitat for natural enemies of insects pests; and nonsynthetic controls, such as lures, traps, and repellents. When these practices are insufficient to prevent or control insect crop pests, a biological, botanical, or chemical material or substance included on the National List of nonsynthetic and synthetic substances is allowed for use in organic crop production to prevent, suppress, or control insect pests. The conditions for using these materials must be documented in the organic system plan.
The USDA National Organic Program allows application of “organic” insecticides when cultural and biological practices are insufficient to prevent or control crop insect pests. The term “organic” has a specific legal definition when it is used to refer to insecticides for organic crop production. The legal definition is drawn from the Organic Food Production Act of 1990, which established national standards for use of the term. An organic pesticide must be produced from materials on the National List of Allowed Synthetic Substances, or come from all-natural substances that are not prohibited. The National Organic Program is administered by the United States Department of Agriculture (USDA) and includes a set of national organic standards, a list of allowed and prohibited substances, and a regulatory oversight structure. The Organic Materials Review Institute (OMRI) is recognized by the USDA National Organic Program as an organic material review organization. It lists products it finds suitable for certified organic production. These products are generally allowed without restriction, but some are regulated and subject to restrictions. In some cases, OMRI notes that certain formulations of a product are permitted and others are not. The list of substances approved by OMRI is subject to change.
Of the major pests that plague organic crop production (weeds, insects and diseases), diseases are by far the most devastating. Plant pathogens are constantly changing and mutating, resulting in new strains and new challenges to growers. Also, given the local, regional, and international movement of seed, plant material, and farming equipment, new and introduced pathogens periodically enter the organic farming system to cause new disease problems. Disease management is complicated by the presence of multiple types of pathogens. For any one crop the grower must deal with a variety of fungi, bacteria, viruses, nematodes. If a plant pathogen is present, the severity of the disease it causes will be determined by the level of infestation, by environmental conditions, and the susceptibility of the crop. A certified organic farm can control plant diseases by implementing a variety of approaches. Good cultural management is a cornerstone to organic disease control, including host resistance, site selection, exclusion, crop rotation, cultivation, and plant disease diagnosis. Fungicides can be used as well, but for organic production, fungicide use is limited to using sulfur, copper, oils and bicarbonates to control plant disease outbreaks. It is unlikely that all diseases can be avoided by utilizing any one of these management strategies alone. However, the damage of many plant diseases can be greatly reduced by the integration of these practices.
Weed management is one of the most challenging issues facing organic farmers and pose important problems such as reduced crop yield if they are not managed and controlled. Specific weeds may also provide alternative hosts for insects and pathogens, as well as interfere with harvest either by interfering with machinery or through crop contamination. Farmers who wish to become organically certified are restricted from using synthetic herbicides for weed control under the U.S. Department of Agriculture’s Final Rule. They meet this challenge by selecting from a wide range of acceptable techniques and strategies, all with the goal of achieving economically acceptable weed control and crop yields. The primary weed control strategies for organic systems are cultural and mechanical, focusing on prevention, crop rotation, crop competition, and cultivation. Ideally, growers would like to achieve a level of zero weeds on the farm. In practice, complete eradication of well-established weeds is not achievable and is generally not the goal of many organic producers. Rather, maintenance of weeds at acceptable levels is both achievable and harmonious with the philosophy of organic production. Consistent weed management can reduce the costs of weed control and contribute to an economical crop production system.
Climate change poses unprecedented challenges to agriculture because of the sensitivity of agricultural productivity and costs to changing climate conditions. Adaptive action offers the potential to manage the effects of climate change by altering patterns of agricultural activity to capitalize on emerging opportunities while minimizing the costs associated with negative effects. The aggregate effects of climate change will ultimately depend on a complex web of adaptive responses to local climate stressors. These adaptive responses may range from farmers adjusting planting patterns and soil management practices in response to more variable weather patterns, to seed producers investing in the development of drought-tolerant varieties, to increased adoption in organic farming practices. Agricultural systems are expected to be fairly resilient to climate change in the short term due to the system’s flexibility to engage in adaptive behaviors such as expansion of irrigated acreage, regional shifts in acreage for specific crops, crop rotations, changes to management decisions such as choice and timing of inputs and cultivation practices, and altered trade patterns compensating for yield changes caused by changing climate patterns. However, by midcentury, when temperature increases are expected to exceed 1°C to 3°C and precipitation extremes intensify, yields of major crops and farm returns are projected to decline.