Soil Erosion and Runoff From Livestock Farms with a Modified No-Till System
Michigan State University
Basin Program Funds:
Much of the most productive farmland in the Great Lakes Region is tile drained. In recent years, livestock producers have become aware of a new hazard associated with liquid manure systems: preferential flow to tile lines through worm holes and macropores when applied to fields farmed under a notill system. In seeking to solve the problem of tile line flow, farmers are considering a return to intensive tillage practices such as moldboard plowing. A return to such tillage practices will leave the soil surface unprotected and increase soil erosion and sedimentation.
In some fields, tile line flow and discharge of manure slurry has been reported within minutes of injection or slurry application. Water quality and tile line flow were topics at a recent meeting in Lenawee county attended by local farmers, extension agents and specialists from Michigan State University, state and federal agencies, and representatives of the Bean Creek Watershed Coalition. While management options to prevent liquid manure from flowing to tile lines have yet to be developed, tillage has been suggested as a likely control measure. Tillage breaks the continuity of worm holes and macropores and may slow the movement of liquid manure through the soil. The level of tillage intensity and the timing of tillage relative to slurry application to inhibit macropore flow are not well known.
On most livestock farms in the Great Lakes Region, control of soil erosion is achieved largely by including forage and hay crops in the crop rotation. Corn ground for silage and grain is generally tilled and left unprotected throughout the winter. But most soil deterioration, ground water contamination and soil loss occurs during the winter. The best way to minimize soil deterioration is to leave crop residue on the surface or plant a cover crop. No-till systems are associated with the least erosion and the least cumulative runoff, but many dairy and livestock farmers have been slow to adopt no-till cropping practices because of the need to incorporate manure for efficient nutrient use. Livestock producers face considerable environmental challenges as they plan for the future. Manure should be injected or incorporated by tillage soon after spreading. Direct injection or rapid incorporation following surface spreading minimizes manure runoff. However, direct injection using conventional equipment disrupts the soil surface and considerable secondary tillage is often needed to level the ground and prepare a seedbed. Intensive tillage can increase soil erosion, sedimentation and nutrient loss to the environment.
A modified no-till system with a rolling tine harrow suitable for use on dairy farms was described by Harrigan et al. in 1996. Such a tillage and planting system reduced machinery costs 25%; fuel costs, 45%; and labor costs, 50% compared to a conventional tillage and planting system. A modified no-till system can help manage shallow soil compaction, improve infiltration, reduce runoff and help to better integrate no-till cropping and livestock systems.
A portable rainfall simulator was used to generate runoff from a consolidated soil (wheat stubble and pasture ground when: 1) undisturbed, 2) loosened with a rolling tine harrow, and 3) loosened with 5,000 gallons per acre of dairy slurry applied. Runoff from each plot was analyzed for sediment and fecal coliform concentration. The overall goal of the project was to evaluate aeration tillage as a soil stabilization tactic and to develop guidelines for its use in the land application of liquid manure. The sediment concentration in runoff from wheat ground following low-intensity aeration tillage was only 35% of that following conventional tillage, and no different than from untilled ground with a 30% residue cover.
When equipped with a manure slurry distribution system, a rolling-tine aerator can be used as a low-disturbance slurry injector whereby the aerator loosens the soil and the slurry is placed directly behind each group of aerator tines. A rolling-tine aerator differs from other slurry injectors in that the tine pattern creates non-continuous pockets which are staggered in a diamond pattern rather than creating continuous channels. This helps prevent overland flow of manure slurry, and helps prevent subsurface flow of manure slurry within the injector path on sloping ground. The aerator disturbs little residue yet effectively loosens the soil in the seed bed. This method of low-intensity tillage provided a striking decrease in overland flow and runoff volume compared to the untilled ground.
A specific objective of this project was to deliver the information developed in the runoff work to a broad range of stakeholders. Two fact sheets outlining the role of tillage, residue management and related soil conservation practices in environmentally responsible farming systems were posted on the world wide web and distributed to all county extension offices. The Agricultural Engineering Information Series (AEIS) fact sheets were published in two parts, targeting farm managers, technical service providers and extension agricultural agents with an interest in writing comprehensive nutrient management plans (CNMP’s) for livestock producers.
Project results were presented at six regional meetings from January 27 to March 31, 2004.
Attendees were farm managers (80%), agribusiness and technical service providers (15%), and regulatory personnel (5%). The total attendance was 171, representing approximately 42,500 acres of cropland and 17,000 dairy cows plus an additional 10,000 steers and heifers. Based on a survey of participants, 92% of attendees reported being better equipped with knowledge to address environmental concerns. Eight-six percent planned to change some aspect of their farm management, and 30% planned to change their manure land application practices.
Project results were presented as 1) a published paper, and 2) a technical poster presentation at the joint International Meeting of the American and Canadian Society of Agricultural Engineers in Ottawa, Ontario in July, 2004. Grant funds were also used in partial sponsorship of a multi-state conference in Columbus, Ohio in November 2004-Liquid Animal Manure Application on Drained Cropland: Preferential Flow Issues and Concerns. Conference participants (approx. 110) included farmers, technical service providers, consultants, university researchers and extension agents, state and national government regulatory agency personnel, and other stakeholders.
Contact: Timothy Harrigan, 517/353-0767