Use of Poultry Litter or Manure for Root-knot Nematode Management on Vegetables and Field Crops

1993 Annual Report for AS93-011

Project Type: Research and Education
Funds awarded in 1993: $0.00
Projected End Date: 12/31/1995
Matching Non-Federal Funds: $109,000.00
ACE Funds: $146,696.00
Region: Southern
State: South Carolina
Principal Investigator:
Bruce A. Fortnum
Clemson University, Plant Pathology & Physiology

Use of Poultry Litter or Manure for Root-knot Nematode Management on Vegetables and Field Crops


Poultry is a large agricultural industry in the southeastern United States. The poultry industry generated an estimated income of $480 million in South Carolina and $1.5 billion in Georgia during 1994-1996. In addition to providing income and food products, the industry generated an estimated 3 million tons of waste annually in South Carolina and Georgia. Although poultry is a significant economic component of agricultural income in the southeastern United States, it also presents a significant challenge to manage and utilize the waste that is generated.

Poultry manure contains significant quantities of fertilizer [Nitrogen (N), Potassium (K) and phosphorus (P) and micronutrients]. Application of litter or manure to land has been viewed as a substitute for mineral fertilizers and as a method for disposing of unwanted waste. The N, P and K components in the manure are equivalent to an estimated $61 million of inorganic fertilizer.

Root knot nematodes, a debilitating plant root parasite, are common in southern soils and are a serious problem on vegetable and field crops. On just two row crops in South Carolina (cotton and tobacco) an estimated $10 million are spent annually on nematicides to control nematodes, whereas in Georgia an estimated $54 million are spent annually to control nematodes on cotton, tobacco and peanuts.
As a result of widespread infestations of root-knot nematodes, nematicides are commonly used in many cropping systems with the potential of contaminating surface and ground water. Nitrogen-rich organic amendments can be used to suppress root-knot nematodes and may provide an alternative to synthetic pesticides.

The specific objectives are to:
1.) Determine if poultry manure or litter (which form is best) can be used, at environmentally sound application rates, to provide fertilizer (N, P, K and micronutrients) for a crop and suppress nematodes.
2.) Determine if the nematode suppression is due to the ammonia in the manure and litter or to organisms in the manures.
3.) Encourage the farm community to utilize this valuable resource.

Poultry litter and manures were collected from several collection systems and found to vary in the percent of total nitrogen as ammonia, one component believed to influence root-knot development. Organic soil amendments (poultry litter and three types of poultry manure) were evaluated for suppression of root-knot nematodes on field grown summer squash cv. Goldbar. Organic amendments or fertilizer were added to soil, incorporated with a power driven rotary hoe, and the rows covered with plastic mulch. Plots were irrigated as needed through trickle tubing. Fertilizer or manure provided comparable quantities of inorganic nitrogen when application of manure was based on 60% of organic nitrogen and 80% of ammonium nitrogen being available to the crop (1993, 1994, 1996). Root galling was lower (1993, P= 0.05) in plots receiving litter amendments when compared to inorganic fertilizer applications.

Poultry manure and litter amendments resulted in squash yields comparable to yields in plots treated with inorganic fertilizer. Nematode damage was light in 1994 and 1996 and may be due in part to the short growing season of squash (45 days to first harvest).

The effects of poultry litter and associated microorganisms on the cotton cultivar DPL50 in litter amended soils were investigated in the greenhouse and in field studies. Root -knot nematode numbers decreased in poultry litter amended treatments. Bacterial, fungi and free living nematodes were increased. Negative linear relationships were observed between nematode numbers and bacterial and fungal numbers. Poultry litter apparently stimulates microbial activity in the soil that is antagonistic to plant parasitic nematodes. Further studies found that poultry litter and manure application decreased root-knot numbers when nematodes were applied as infected root pieces but not as eggs, egg masses or juveniles.
Ammonia (NH3) released from litter and manure is another factor that may be detrimental to root-knot nematodes. Over a 14 day period 32.9%, 40.3%, 62.6%, and 50.1% of the total N was volatilized as NH3 from litter, high-rise, belt and chain manures, respectively. The NH3 generated remains as NH3 as long as soil pH remains high.

Application of poultry manure and litter significantly increase soil pH shortly after application. Soil pH rose from 5.63 to 8.29 units within 48 hours when manures were added to soil at a rate of 360 kg of N/ha. This soil pH is sufficient to maintain the N in the NH3 form.

The ability of poultry litter or manures to reduce root-knot disease will enhance the value of these agricultural wastes increasing there acceptance into integrated production systems. The successful adaptation of manure or poultry litter, as a nematode suppressants, depends on the economic benefits from the application of the manures balanced by the increased cost of transportation.

A comparison of fertility costs between farms spreading poultry litter at the rate of two tons per acre and farms using all commercial fertilizer indicates a slight cost advantage to spreading litter on corn and double-cropped soybeans/wheat. Individual producers with surplus on-farm labor could realize greater cost savings by spreading litter. Conversely, producers without the equipment to efficiently handle the litter could see higher labor costs that eliminate any cost savings from applying poultry litter to their crops.
December 1997