The ecological impact of various alternative farming practices are not well documented in North Dakota. Since both farm policy, and increasingly environmental policy and regulation, have direct influence on the types of farm practices being employed, a study was undertaken during the 1990 and 1991 crop seasons to compare what were deemed the most successful of alternative farm practices in North Dakota. Two farmer organizations, the Manitoba/North Dakota Zero-Till Association and the Northern Plains Sustainable Agriculture Society, both whom have championed alternative practices aimed at sustainability, helped define the objective and coose actual farms to study. These organizations represented the expertise and development of alternative tillage (ManNDZTA) and rotation (NPSAS) practices across North Dakota.

Though an experimental approach (such as an agricultural experiment station trial) has long been used to identify improved methods of tillage, rotation, or pest management in isolation, little if any data currently exist to compare the relative impact of these practices as they are actually employed in a system on the farm. Though it is difficult to categorize farms and farmers, three distinct farm management approaches were chosen for comparison in North Dakota based upon the length of time and success of farmer-driven organizations promoting their adoption. All had been successfully using their current management practices for more than ten years. The agroecosystems compared included the following:

Identification Description

Conventional farms successful using practices which were predominant in region

No-till farms making extensive use of conservation (or no) tillage

Organic farms making extensive use of crop rotation to substitute for little

(or no) pesticide or fertilizer inputs

Since North Dakota has three dominate eco-regions (1) west of Missouri River, characterized by mixed-to-shortgrass prairie and residual soils, 2) the central region, east of the Missouri and west of the Red River Valley, called the Coteau or pothole prairie due to glaciation and mixed grass prairies; and 3) the Red River Valley, the residual of a glacial lake with deep fine-textured soils and a mixed-to-tall grass prairie.) sites of each type were carefully chosen in each region which had at least some similar soils. Though general data were taken from each whole farm, one specific site (field) per farm was chosen with soil types which matched other sites within a region. These sites were visited bi-weekly throughout the 1990 and 1991 growing seasons to measure environmental impacts physically on the soil, chemically on soil nutrient use and efficiency and biologically both above and below ground. Success of these farms measured by productivity or environmental impact has not necessarily insured equal economic success. Companion studies lead by Dave Watt in the Agricultural Economic Dept. were conducted to compare these farms for interaction with their economic and social communities (reports are available from the NDSU Ag Economics Dept.). Complete results of the study are found in a recently published Agricultural Experiment Station Bulletin entitled, ‘Farming Practices for a Sustainable Agriculture in North Dakota’. Highlights of the results which emphasize the comparative impact of alternative tillage and rotation practices follow.

Soil organic matter levels were greatest at the no-till sites, and generally least at the conventional sites. Reducing tillage and/or increasing the organic matter inputs through applications of green or livestock manure were both effective in increasing the organic matter inputs.

Organic matter is an important determinant in the quality of prairie soils. It influences infiltration, runoff, the ease which erosion can take place, compaction, the frequency green or livestock manure were both effective in increasing the organic matter content. Organic matter is an important determinant in the quality of prairie soils. It influences infiltration, runoff, the ease which erosion can take place, compaction the frequency of soil crusting problems, and also serves as a slow--release nutrient bank. We are now beginning studies to compare the organic matter itself depending upon whether it was raised through reducing tillage or increasing organic matter inputs.

Soil nutrient content was variable among farm types. Sits where tillage was decreased, but cropping frequency was not increased, tended to have excess nitrogen below the root zone. Though the tendency was for the organic sites to have the least amount of inorganic N or P available, it was dependent upon the date of soil sampling, a d phase in the rotation of the organic farm. Typically, organic farms include a green manured legume as often as necessary to supply the N needed for several following crops. Thus if sampling occurred after the green manure, levels were high. Supplying nutrients through green and livestock manures tended to change the path of nutrient cycling within the soil. Frequently, we found low levels of inorganic nutrients among organic farms through crops did not appear deficient.