The Open Furrow Projects Behind the Wire Dirt Hog's Companion On Point Explorations Agrosphere Journal

plowmans Dust jacket from an early edition of Plowman's Folly by Edward Faulkner (1943). It's hard to imagine a book about tillage becoming a national bestseller but Plowman's Folly went through eight printings in its first year alone, insuring financial success for the fledgling University of Oklahoma press. The cover endorsement is by Louis Bromfield. Bromfield was a pioneer of conservation farming in the 1940s in Ohio and a contemporary of Faulkner.


soils and Men "The Earth is the mother of us all-plants, animals and men." So begins Henry A. Wallace's foreword to the 1938 USDA Yearbook of Agriculture "Soils and Men". No other book like it has ever been written, and probably never will. "Soils and Men" stands as a timely examination of soil, society, and agriculture urged on by 1930s era calamities like the dustbowl, farm insecurity, and soil depletion. The enduring value of its 1,232 pages and appended "Soil Associations of the United States" map, largely rests on the scholarly contributions of North American soil science pioneers: Utz, Kellogg, Stallings, Bennett, Pierre, Albrecht, Troug, Lowdermilk, to name a few. Notably missing is Marbut, see below.

soils and Men Curtis Fletcher Marbut 1863-1935 "Mr. Marbut was for many years chief of the Soil Survey Division in the United States Department of Agriculture. Under his guidance, work in soils became a recognized science in the United States. His own researches in soil classification and geography laid the foundation for our modern concepts of soil. His devotion to truth and freedom from prejudice were coupled with a modest, kindly personality that inspired all his associates as well as young men everywhere who were interested in soil science. Although he became a citizen of the world, he retained the simple habits of his early life in the Missouri Ozarks. He died at Harbin, Manchuria, while on an expedition to China." -Soils and Men, 1938.

The Soil Under Shifting Cultivation British soil scientists Peter Hague Nye (1921-2009) and Dennis J. Greenland (1930-2012) aren't household names but their landmark publication The Soil Under Shifting Cultivation (1960) was the first quantitative study of soil fertility and nutrient cycling under slash and burn agriculture in the humid tropical rainforest and savannah zones. Nye and Greenland's careful study of nutrient flows and soil-crop productivity, drawn from their research in Ghana, West Africa as well as published data since the 1930s has stood the test of time, forming the basis 15 years later by B.T. Kang, P.A. Sanchez, R. Lal and others in finding alternatives to slash and burn. The book is still highly relevant to the science of land use and climate change.

slash-and-burn Slash and burn farm, Kenema District, Sierra Leone.

Tillage and Soil Productivity Research

Since humans began shaping tools to cut, lift, crush, invert, and mix the soil, tillage has become intimately associated with the idea of ‘land husbandry’. The soil's memory of tillage practices may linger over months, seasons, decades, or millenia depending on soil texture, structure, drainage, water content, crop rotation, and patterns of rainfall and air temperature. These factors interact with tillage in a complex manner that is often obscured by short-term investigations. Ongoing support for long-term field trials is crucial for assessing tillage effects on soil properties and their relationship to short- and long-term crop productivity.

In 1984, researchers in NCSU's Department of Soil Science established two tillage trials, both on fine, kaolinitic, thermic Typic Kanhapludults at the Upper Piedmont Research Station, Reidsville, NC. The Reidsville tillage plots have served as a platform for diverse investigations related to soil-crop productivity and environmental stewardship for over a quarter century. Eleven research articles have been published in major peer-reviewed scientific journals, and a growing public-private partnership seeks to preserve these unique historic trials for future research.

We present a survey of this research (see below) in an interpretive context, sharing insights we have gained about tillage effects on the physical properties and productivity of southeastern U.S. Piedmont Ultisols.

Assessing Soil Moisture Dynamics in Long-term Tillage Systems

Characterization of soil-water-plant relationships among different tillage systems has typically been limited to measurement of surface residue and soil properties in the Ap horizon. There is relatively little information about soil profile moisture dynamics in different tillage systems and their relationship to short- and long-term productivity. The goal of this ongoing project funded by the Soybean Growers Association of North Carolina, Inc. is to evaluate soil profile moisture dynamics in two long-term tillage trials, both on fine, kaolinitic, thermic Typic Kanhapludults at the Upper Piedmont Research Station, Reidsville, NC. We used a Dynamax PR2/6 capacitance probe (Delta-T Devices, Ltd., Cambridge, UK) which estimates soil moisture via its dielectric constant similar to time domain reflectometry (TDR) and without the radiation hazards of the neutron probe. Project leaders: Jeffrey G. White, Robert D. Walters, Joshua L. Heitman, and Adam M. Howard.

Assessing Compaction, Aggregation, and Carbon in Long-term Tillage Systems

The southeastern Piedmont occupies an area of approximately 16 million hectares with upland soils dominated by Typic Kanhapludults derived from felsic crystalline rock. Row crops are grown on sloping land, and on sandy to sandy clay loam soils low in carbon, aggregate stability, water holding capacity, and prone to erosion, crusting and compaction. The soils are, however, highly responsive to conservation practices associated with minimum and no-tillage. The purpose of this research was to assess the impact of long-term and sharply contrasting tillage on: (1) soil physical properties at two depths and three row position in the surface Ap horizon; (2) the relationship between compaction and pore size distribution; (3) the relationship between soil carbon and macroaggregate (1-4mm) stability; and (5) corn productivity. We used two, long-term tillage trials, both on fine, kaolinitic, thermic Typic Kanhapludults, established in 1984 at the Upper Piedmont Research Station, Reidsville, NC. This research was made possible by a grant from the Corn Grower's Association of North Carolina, Inc. Project leaders: Robert D. Walters, Michael G. Wagger, Jeffrey G. White.

Agrosphere Modeling for Producing Large Increases in Food Yield (AMPLIFY)

AMPLIFY is a public-private research platform designed to propel innovation and resource-efficient methods to increase food yields. Created by the College of Agriculture and Life Sciences of N.C. State University, AMPLIFY was conceived as a transdisciplinary, entrepreneurial platform providing infrastructure for mobilizing research capability and intellectual capacity to solve complex global issues in agriculture. Advances in telemetry, remote sensing and digital imaging, and precision machine guidance systems are generating multi-dimensional information that could drive agricultural decision-making at ground level and beyond, if we know how to harness it. By pulling together basic and applied expertise from the N.C. State’s College of Agriculture and Life Sciences, College of Sciences, and College of Engineering, AMPLFY seeks to: (1) model photosynthesis, carbon metabolism and partitioning, and water use efficiency (2) develop custom hyperspectral imaging systems for a seamless, integrated high-throughput phenomics pipeline; (3) fuse remote sensing information to quantify crop phenology, biomass, and soil-plant nutrient and water status; (4) model and identify high performance, resilient yield traits and create improved management strategies and decision support tools. Previews available here:

Improved Agronomic Practices for Cassava Production

Cassava (Manihot esculenta Crantz, family Euphorbiaceae), is a tropical root crop that tolerates uncertain rainfall, long dry periods, and poor soil. Cassava is a source of food, livestock feed, and income generation for some 800 million people, for whom it also holds strategic potential as a famine reserve crop. Lately, cassava has attracted interest as a bio-energy crop with potential as a cash crop for smallholders.

Africa produces over 50% of the world's cassava, but the continent lags behind its global peers in productivity per hectare. Cassava is popular with African farmers because it is amenable to mixed cropping, with processing and infrastructure technology firmly embedded in many local and regional food systems. Surplus production coupled with growing industrial demand has stimulated commercial exploitation of the root. In turn, improved varieties, mechanization, and agronomic practices have become focal points in boosting Africa's cassava yield curve.

The Improved Agronomic Practices for Cassava Production assignment was initiated in Ghana, West Africa by ACDI/VOCA under USAID's Farmer To Farmer Program (F2F) authorized by the U.S. Congress in the Farm Bill. Primary in-country host was Caltech Ventures Limited (CVL), a commercial producer of cassava starch, flour, and starting 2015, ethanol. CVL has 3,000 hectares of farmland in the Volta region near Ho, of which 350 hectares are under cultivation either by CVL directly, or by outgrowers who produce cassava for CVL under agreement in exchange for crop inputs and marketing support.

The objectives for this assignment were to: (1) assess the current practices of CVL's farm and that of their outgrowers and provide recommendations for improvement; (2) based on the assessment, train staff on best practices to boost production; (3) train CVL on how to mechanize their operation; (4) develop a cassava production manual to guide CVL in their farming operations; and (5) make recommendations on any other professional support that will strengthen the CVL in its operations.

Improved Compost Preparation and Technology

Composting has come a long way since the days of Sir Albert Howard and the Indore experiments. Once an arcane, if faintly suspect, practice of organic farmers and gardeners, composting has evolved to a full-fledged science with built-in engineering controls that make the composting process predictable and much more efficient. Material properties like carbon to nitrogen ratio (C:N ratio), bulk density, moisture, and porosity influence microbial decomposition of waste material in compost. Knowledge of the optimal conditions for microbial decomposition ensures efficient bioconversion of waste products so that they can be beneficially and safely used as fertilizers and soil conditioners.

The Improved Composting Production and Technology Project (BAN320) was initiated in Bangladesh under the The John Ogonowski-Doug Bereuter Farmer-to-Farmer Program jointly administered by USAID and Winrock International. This Project aimed to (1) provide training in improved compost preparation in Bangladesh; (2) build capacity for composting as an environmentally sound method of converting agro- and municipal solid waste into useful products; and (3) increase awareness of the role of organic matter in sustaining soil productivity. The Project's primary in-country host was Bismillah Fish and Poultry Farm (BFP), an integrated agro based enterprise comprising fish and prawn culture, 20,000 poultry layers with capacity for up to 40,000 birds, cow fattening and milking, and vegetable growing. Local traditional methods are used for composting poultry manure, cow dung, and other waste, which largely remains unused due to lack of better knowledge. BFP also wants to increase composting capacity by using different types of locally available raw materials (cow dung, water hyacinth, farm by-products, etc.) and marketing their excess compost fertilizer. The compost will be used as a fertilizer and soil conditioner for vegetables and other agricultural crops in the Khulna region.

Effects of Biochar on Soil Properties and Corn, Wheat, and Soybean Yield

Biochar is the charcoal remains of incomplete combustion of biomass (e.g. woodchips, brush, greenwaste). Biomass is heated to extract biofuel (biodiesel) in a process called torrefaction. Biochar via "slash and smolder" has been implicated in highly productive terra preta soils of South America. When added to soil, biochar may (1) sequester carbon; (2) slow nutrient leaching; (3) increase nutrient availability; (4) decrease fertilizer requirements; (4)improve water relations; and (5) stimulate beneficial soil fungi. The purpose of this on-going research is to assess the effects of five levels of biochar application (0, 10, 20, 40, 80 t/ha) and two fertilizer treatments (+/- N, P, K) on crop growth and productivity on a Noboco loamy sand soil in Duplin County, NC. Project leaders: Jeffrey G. White, Robert D. Walters (Department of Soil Science), Michael Boyette (Agriculture and Biosystems Engineering).

Mineralization and Plant Availability of Nitrogen and Phosphorus in Municipal Biosolids

Biosolids are the solid or semisolid, largely organic, nutrient-rich residuals of wastewater (sewage) treatment, i.e., sludge treated to meet EPA (and sometimes state) land application standards so that they can be used beneficially and safely as a fertilizer or soil amendment. Similar to livestock organics, the nutrient content of biosolids may vary considerably, depending on influent waste properties and treatment process. This research aims to determine nitrogen (N) and phosphorus (P) availability coefficients of different types of biosolids applied to North Carolina's diverse soils to determine application rates appropriate for crop needs and water quality protection.


Residue Management Options in Conservation Tillage: Adaptive Research Directed Toward Cotton and Soybean Production in the Southeast

A residue management tool, the mechanical roller-crimper, has long been used by farmers in the southern Brazilian sub-tropical states of Rio Grande do Sol and Paraná to manage high density cover crop residues in production systems using the guiding principles of "zero tillage". The roller-crimper uses the weight of a cylindrical drum mounted with iron blades around its circumference to flatten and crimp standing residue, leaving a pressed, soil protective and weed suppressive blanket of mulch into which the principal crop may be planted. The objectives of this two-year project were: (1) to evaluate the effect of surface pressed, intact residue and residue orientation on weed suppression using different weed control programs; (2) examine the relationship between residue decomposition and incident weed pressure; and (3) evaluate the effect of residue management on cotton and soybean stand establishment and yield. The project was conducted at the Center for Environmental Farming Systems in Goldsboro, NC. Project leaders: Robert D. Walters, Michael G. Wagger (Department of Soil Science), Keith R. Baldwin (NC A&T University).

What did we learn about the mechanical roller? Get the details in the following reports:

Effect of Soil Texture on The Performance of a Subsoiling Implement

Many soils in North Carolina's coastal plain have a dense, compacted sandy layer, or 'E' horizon, underlying the Ap horizon. The E horizon is a naturally occurring product of geologic history and, in soil where it occurs, requires sub-soiling by growers on an annual or semi-annual basis to loosen the layer for crop production. Depth to the E horizon varies spatially in the landscape and, consequently, growers must find a "happy medium" for subsoiler depth adjustment. When the ripper shanks are adjusted too deep, clay in the Bt horizon may be brought to the surface, resulting in an undesirable environment for seed germination and seedling growth. This 8-week project introduced summer interns at the Center for Environmental Farming Systems in Goldsboro, NC to the art and science of troubleshooting soil and crop production problems. The interns' objectives were to (1) examine the cause of subsoil "blow-out" in two of four blocks in a replicated cotton trial in 2004 by analyzing soil particle size distribution; and (2) make recommendations the overcome the problem. Project leader: Robert D. Walters. Note: the author is no longer active in the intern program.

On the Ground: Troubleshooting Soil and Crop Productivity

This 8-week project introduced agriculture interns to agronomic problem solving. Working together as a team, interns were expected to: (1) develop an ability to observe, identify, and differentiate visual indicators of crop health and productivity; (2) acquire skill in measurement of soil physical and chemical properties and results interpretation; and (3) draw conclusions and make recommendations based on soil-plant-environment data. The investigation focused on several discontinuous areas of unusually poor crop growth in a crop-animal rotation component of the SARE long-term cropping systems experiment at the Center for Environmental Farming Systems, Goldsboro, NC. The team's objectives were: (1) identify the growth-limiting factors in the SARE crop animal rotation component; (2) make specific recommendations to overcome these limitations; and (3) suggest management strategies to enhance long-term soil productivity. Project leaders: Robert D. Walters, Joel B. Gruver.

This site was created by Robert D. Walters in consultation with Jijy Thanwalee. Reproduction of author's content by permission only. Questions and/or comments about this site may be directed to This site and all content within it have not been endorsed by N.C. State University. Directory information for Robert D. Walters available here (via Linkedin).

This page was last modified on 24-Jan-2017 .