The Agricultural and Ecological Functioning of a System Integrating Pastured Poultry and Raised-Bed Vegetable Production.

View the project final report

• 2005 annual report

Commodities

• Agronomic: grass (misc. annual), grass (misc. perennial), medics/alfalfa
• Animals: poultry

Practices

• Animal Production: grazing - continuous, grazing - multispecies, grazing - rotational
• Natural Resources/Environment: biodiversity
• Pest Management: prevention
• Production Systems: agroecosystems
• Soil Management: nutrient mineralization, organic matter

The use of integrated cropping systems to promote a more profitable and ecological agriculture is of interest to many farmers today. To test the hypothesis that the restoration of ecosystem functions to crop lands will allow farms to maintain productivity while improving land health, plots integrating pastured poultry and vegetable production were constructed. Vegetables were produced in raised beds built in the middle of pasture plots of differing diversity and grazing intensity. Chickens housed in bottomless shelters were rotationally grazed around the vegetable beds in each pasture. A control with vegetables surrounded by a clean cultivated, ungrazed ‘pasture’ area was included in the treatments. The effects of pasture composition and poultry grazing on pasture, vegetable, and poultry productivity and profitability, invertebrate populations, and soil nutrients were examined.

Dressed weight of poultry was not affected by pasture type (p=0.60). Vegetable yields were affected by pasture type and grazing, but varied by crop. Pasture productivity, quality, and composition were affected by the grazing as well as the initial species composition. Diverse pastures were more resistant to weed invasion (< 2% of biomass), and the grazed mix yielded more forage biomass during peak production seasons than the ungrazed mix or monoculture pastures (p<0.05). Fall harvested forage from the grazed mix had highest levels of crude protein (23%), phosphorus (0.4%) and potassium (3.2%). Squash bug egg abundance was reduced in gardens surrounded by grazed compared to ungrazed pastures (p=0.038). Abundances of spiders, carabid beetles, and collembolans were higher in grazed pastures throughout most of the field season, and parasitic hymenopterans were most abundant within the garden areas surrounded by the grazed diverse pastures. The diverse pasture soil surface showed greatest abundance of worm casts (~1000/m2), indicating greater numbers or activity of these soil builders. Soil microbial biomass and N and C mineralization potentials were not influenced by the treatments. Pasture soil content of P, K, and total N, were increased by grazing and all pasture-based systems showed higher levels of total C than the tilled system. Additionally, the grazed systems improved overall profitability by offering an additional income stream and reducing production costs compared to the tilled system. These results indicate that a system integrating rotational poultry grazing and annual vegetable production offers farmers a viable and flexible method for addressing both agronomic and environmental concerns.

Introduction:

Contemporary thinking in alternative agriculture is bringing into question the very nature of farming itself. The problems within agriculture such as pests, yield fluctuations, and diseases are considered secondary to the problem of agriculture; the thesis being that we are sustained by a fundamentally flawed model of food production (Jackson, 1980). The industrial model of agricultural production is problematic in that it displaces farmers on a massive scale, erodes the very materials which sustain it, consumes material input en masse, is wholly dependent upon finite resources and, lastly, engenders a treadmill of problems, solutions, and then problems with the solutions such as pesticide resistance or the inverse relationship between yield and commodity profitability.

In considering an alternative approach, this study aims to develop and examine an agricultural system that is: 1) productive and economical, and 2) possesses ecologically restorative properties. Such a system could enhance the momentum of new agrarianism, revitalize dilapidated farmsteads, and mitigate perceived profit losses on farm property being devoted to conservation initiatives. The goal is to understand how people may “assemble synthetic communities of plants, animals, and microorganisms that are stable, productive, and close enough in form to the native community that the essential functions of pest resistance, soil stability, and nutrient cycling are preserved (Anonymous, 2005).” To do so, this project assembled communities consisting of vegetable crops planted in raised beds surrounded by a border area that were then grazed by broiler chickens (Gallus gallus) in a rotational system.

• To test the hypothesis that ecologically functional agricultural systems can enhance land health while sustaining agricultural productivity, this research addressed the following objectives:
  To evaluate how pasture diversity and grazing affects forage, poultry, and vegetable productivity.

  To determine whether increased pasture diversity combined with poultry grazing helps reduce insect pest populations and weed invasion.

  To measure how this integrated system influenced soil nutrient content.

  To quantify the economic capacity of these systems.