Settled Soil
Total Page：16
File Type：pdf, Size：1020Kb
DR PATRICK CARR ET AL CARR ET DR PATRICK Settled soil Drs Patrick Carr, Greta Gramig and Mark Liebig offer an interesting insight into why there is a growing trend towards zero-tillage farming practices in semi-arid areas and the importance of sustainability primarily on weed control in organic crop production systems. I am interested in how tillage, cover crops and crop rotations affect weed population dynamics, both directly and indirectly via effects on weed seed predators. ML: My role has been to share what I’ve learned about soil quality in organic production systems and reduced/zero-till cropping practices throughout the North American Great Plains. My work in this area started as a graduate student in the early 1990s and has continued in my current role as a research soil Historically, tillage was used in crop only 420 mm – makes finding reliable, fall- scientist with the US Department of Agriculture production on a global scale. Why has seeded cover crop species more challenging (USDA)’s Agricultural Research Service. there been a recent trend towards reduced than in many other environments. Most and zero-tillage approaches? recently, we’ve begun exploring continuous, How is the relationship between soils organic zero-till. Without doubt, an inability and surrounding wildlife affected by PC,GG&ML: Growing appreciation for the to control weeds is the primary obstacle to farming techniques? importance of maintaining or enhancing soil overcome in organic zero-till, particularly when quality and the deleterious impacts of tillage attempting to do so continuously. PC,GG&ML: Farming practices prevalent in explains some of the interest in reduced and organic zero-tillage systems such as cover zero-tillage approaches. In the North American Can you outline your respective roles cropping can have a dramatic influence on Great Plains, the ability to conserve soil water within the project, and the expertise you wildlife such as birds, small mammals and by adopting conservation tillage practices bring to the investigation? insects, while concurrently providing numerous is also a major driver toward reduced and soil health benefits. Cover crops provide particularly zero-till systems. PC: I have served as a research agronomist in protection and habitat for various species. This the Agricultural Experiment Station at North can have both positive and negative impacts What are the scientific objectives of your Dakota State University since 1989. I am on farming outcomes. For example, increased study on the impacts of organic zero-tillage located at a research/outreach centre 480 presence of seed-consuming herbivores can systems on crops, weeds and soil quality? km from the main campus. I began working help regulate weed populations by reducing on conventional zero-till systems in the the number of seeds that are added to the soil PC,GG&ML: We have actually conducted and mid-1980s and so had experience on zero-till seed bank, but these same herbivores may also continue to conduct multiple projects looking methods when I started working on organic damage the crop. at organic zero-till farming. Much of our effort zero-till in 2008. has been focused on identifying single species In what ways are these issues affecting the cover crops that can be used in these systems. GG: I have served as a weed biologist and North American landscape in particular? The Plains’ harsh environment – where winter ecologist for the Department of Plant Sciences temperatures drop below -30 oC, summer highs at North Dakota State University since 2008. PC,GG&ML: Increasing cropping system can exceed 38 oC and annual precipitation is During that time, I have focused my research intensity and diversity results in improved 38 INTERNATIONAL INNOVATION DR PATRICK CARR ET AL Plainly organic The North American Great Plains offer fl at grasslands ripe for farming, but cold, harsh winters and hot, humid summers present challenges, particularly when attempting to implement sustainable practices. A group of experts from North Dakota State University and the US Department of Agriculture’s Agricultural Research Service is investigating zero-tillage systems in this region and their associated impacts, hoping to change farming practices for the better SOIL MANAGEMENT HAS been a topic of the widespread adoption of organic practices debate for almost three centuries. In 1731, on the basis that there is not only a growing British inventor and agronomist Jethro Tull demand for such products but, signifi cantly, published The New Horse Houghing Husbandry: innovations in this area can often be applied to Or an Essay on the Principles of Tillage and conventional farming techniques, making them Vegetation, which presented ideas that would more sustainable and environmentally benign. later form the basis of modern agriculture and bring about the British Agricultural Revolution. THE DUST BOWL A cornerstone of his treatise was the practice of tillage – disturbing the soil through digging, Most organic farmers rely on tillage to remove stirring or overturning in order to break up large weeds from their fi elds, but the effects on the soil particles so that their nutrients can be land can be extreme. A classic example is when extracted by plant roots more easily. Tilling is farmers in the 1920s extensively deep ploughed also used to remove weeds, shape the soil into the virgin topsoil of the North American Great rows for crop plants and furrows for irrigation. Plains. The following decade became known as effi ciencies of converting sunlight and the Dust Bowl, or the Dirty Thirties, because precipitation to grain, forage or other The idea that plants derive their nutrition from deep-rooted grasses that normally trapped harvestable products. Soil erosion can soil organic matter persisted until the 19th soil and moisture had been uprooted, leading be reduced if not eliminated completely Century when German chemist Justus von Liebig (in combination with drought) to years of dust and, and at least in our region, soil carbon argued that plants obtained nutrients contained storms that obliterated agriculture in the area. sequestration occurs when zero-till methods in mineral compounds and not directly from soil are adopted. Overall, the ecosystem services organic matter. This fundamental insight led to With this history in mind, it may seem surprising provided by agro-ecosystems following the the use of synthetic fertiliser by most farmers that scientists are investigating the viability adoption of zero-till are enhanced in the to correct nutrient defi ciencies in agricultural of organic farming on the Great Plains, but North American Great Plains and similar soils and the later development of synthetic a team from North Dakota State University environments following the adoption of herbicides in the 1940s. and the US Department of Agriculture’s zero-till methods. Agricultural Research Service believes the region However, concerns over the effects of fertilisers has potential. Will more responsible stewardship and herbicides on soil quality and the wider in managing soil improve yield and ecosystem, and the quality of crop produced, ZERO-TILL ORGANIC FARMING agricultural practices? led to a growth in organic farming practices in the 20th Century, and subsequently an Drs Patrick Carr, Greta Gramig and Mark Liebig PC,GG&ML: We believe that developing and increase in interest from scientists to research and their collaborators are comparing various adopting agricultural systems that enhance such methods. Supplying adequate food for a methods of weed management and the impact soil quality allows for the production of crop growing world population will be a challenge of zero-till organic farming on soil quality and yields that are sustainable and profi table with purely organic methods, especially in light subsequent effects on food crop quality. “We over the long term. So, putting into practice of increasing demand for meat and high levels of want to develop organic zero-till systems agricultural systems like zero-till that enhance food wastage. Nevertheless, many now support that can be adopted and used successfully by soil quality makes logical economic sense. You hope to create a transatlantic network between European and North American researchers; how will this benefi t your work? What success have you seen here so far? PC: Most of my North American colleagues conducting research on organic farming methods recognise the wealth of knowledge and experience among our counterparts in Europe. I and others have found European researchers to be very open and willing to share their knowledge with us and hope that communication channels will continue and even expand. SEEDING INTO RYE © TIM WINCH WWW.INTERNATIONALINNOVATION.COM 39 INTELLIGENCE SAMPLING ABOVE GROUND BIOMASS IN OVERVIEW OF THE IMPACTS OF ORGANIC NO-TILL PEA PLOTS ZERO-TILLAGE SYSTEMS ON CROPS, WEEDS AND SOIL QUALITY OBJECTIVES • Devise strategies for transitioning from crop and crop/livestock enterprises using conventional practices to organic production methods that are profi table and maintain or enhance soil resources • Formulate weed control approaches in fi eld and horticultural crops that do not rely on intensive tillage, are effective and economical, and are permitted under certifi ed organic guidelines • Identify morphological and phenotypical Upcoming growth traits along with genotypes of event horticultural, oilseed, pulse, and small- grain crops that are adapted to organic Innovations in Organic production systems Food Systems • Determine if organic zero-tillage systems are viable alternatives to conventional organic 1-2 November 2014 commercial organic farmers as Carr highlights: “Greta, Mark farming systems in western North Dakota Long Beach, in the North American prairie and myself all bring different and similar agro-ecoregions California region,” summarise the researchers. knowledge to the study of organic PARTNERS zero-till, which I think is a refl ection USA: Montana State University • Northern It is already known that zero-till systems of the work required to understand all Plains Sustainable Agriculture Society • conserve soil water, which translates into the interactions that are occurring”.