Trials to assess effect of pastured poultry on crops planted after the birds show that the optimum time for planting mustards, cucumbers and squash is 7 to 14 days after the birds have been on the area. Trials assessing the fertilizing effect of the chickens using squash and cucumber indicate that, after the birds have been on the area, conventional fertilizer application can be reduced by 50%.
The objectives of this project were to:
Determine the effect of the manure on plant performance at various times after the pastured poultry have been on the area;
To determine the response of soil fertility and crop yields to manure from previously pastured poultry at the Southern University Horticulture Farm and on producers farms;
To carry out economic analyses of the system; and
To develop information for producers regarding economic advantages and cultural practices relative to growing vegetables in association with pastured poultry, to recruit new pastured poultry and vegetable producers, and to involve producer organizations in promotion of the program.
Limited resource farmers often need alternative diversified enterprises, including niche markets, if they are to survive as producers. Integration of pastured poultry and vegetable production is one system that could increase farm diversity, soil fertility and income for farmers.
There are a number of models for rearing poultry on pasture using a variety of housing and management systems. A feasible income source for established farmers can be achieved by implementing a complete broiler production, processing, and sales system. The system involves rearing broiler chickens on pasture in movable pens, processing the birds on the farm and marketing directly to consumers. This system has also been shown to be practical for small-scale limited resource farmers. The “chicken tractor” has been used to increase the fertility of the vegetable garden. Use of the chicken tractor required reducing the cropping area of the garden, but actually resulted in increased yields due to the fertility imparted by the chickens
Poultry manure has long been recognized as a desirable organic fertilizer because it contains many of the elements required to grow plants. The amount and composition of chicken manure varies with type of feed, bird age and management but an average tonne of fresh chicken manure (no litter) contains about 12 kg of N, 8 kg of P2O5, and 5 kg of K2O . In addition to increasing the soil fertility, such animal manure serves as a soil amendment by adding organic matter to the soil. Although the rate of organic matter decomposition varies with temperature, drainage, rainfall, and other environmental factors, it greatly improves water holding capacity, soil aeration, soil structure, nutrient retention and microbial activities.
Land application of manure can produce crop yields equivalent to those attainable with inorganic fertilizers. Preliminary studies at Southern University showed that, at 14 days of age, broilers produce about 25 grams of manure daily. This increases to 55 grams per day at 56 days of age and contains nitrogen concentrations in excess of 4%. This manure can be an important source of nitrogen within a cropping system. Preliminary studies on the Southern University Horticulture farm indicated that fecal matter from the birds increased soil nitrogen by as much as 0.25%. Furthermore, forage from clover planted on the site a month after the birds were removed and harvested early the following spring had 3.67% nitrogen as compared to the non-manure treated controls which had 3.04% nitrogen. Clover grown on the manured land had over 50% greater forage yield and growth rate as compared to that on non-manured soil. Yields of vegetable crops (chayote and golden berry) obtained from land fertilized with chicken and rabbit manure were comparable to those with chemical fertilizers. These responses were attributed to the nutrients and improved soil conditions provided by the manure resulting in decreased crop water stress.
Poultry manure has long been recognized as a nutrient source for vegetable crops. The manure and or litter has been successfully utilized to produce a variety of vegetable crops including lettuce, snap beans, cabbage and squash. Tomato, sweet corn, pepper, eggplant, cantaloupe, cucumber, watermelon, squash, and pumpkin are crops which efficiently utilize the nutrients from poultry manure. Cucumber, watermelon, peas and limas produced with poultry manure and inorganic fertilizer produced equivalent yields regardless of the nutrient source.
For long season crops such as tomatoes, that require more nutrients later in the growing season, poultry manure slowly releases the nitrogen when it is most needed. Because of the ability of the manure to release the nutrients more slowly, a considerable amount of nutrients is still available toward the latter part of the growing season. Unlike commercial fertilizers, a large portion of the nitrogen from poultry manure remains in the root area when that of commercial fertilizers would have been leached from the root system.
Field experiments were conducted at the Southern University Horticulture farm on a Scotlandville silt loam soil. Between fall 1999 and spring 2001, mustards (Crucifereae), squash (Cucurbitaceae), cucumbers (Cucubitaceae) and collards (Crucifereae) were grown on ridged plots consisting of three rows 80 cm apart and 2.4 m long. Supplementary drip irrigation was applied as needed and the amount applied was documented. The experimental design for the time of planting trials was a randomized complete block with four planting times as treatments (0, 7, 14, and 21 days after pastured poultry had been on the area) with three replications. It was intended that crops would be replicated across years and between the time of planting and fertilizer trials, but losses due to insects and flooding prevented that. Harvesting was staggered according to the planting dates.
To evaluate the effect on soil fertility and crop yields, five fertilizer treatments were used with six replications for each crop. The treatments were chicken manure (CM) only, CM supplemented by 50% of the recommended amount of conventional fertilizer (13-13-13) (SF), CM supplemented by 50% of the recommended amount of organic fertilizer (cotton seed meal, 6- 2.5- 1.7), SF only, and organic fertilizer only. No fertilizer trial was possible in Fall 1999 and the Fall 2000 mustard crop was lost due to severe insect damage.
For each trial and replicate, three 46 cm high pens (240 x 240 cm) representing three plots with 25 mature White Leghorn laying hens in each were moved daily on subsoiled but otherwise undisturbed soil that had adequate grass cover for the birds. Birds were provided with semi-automatic waterers in the pens and were free fed a commercial, crumbled layer ration providing 16% crude protein. Because the primary interest was the fertilizer effect of the birds, egg production was not monitored.
The manure left behind was incorporated into the soil daily after moving the birds to the next plots. No pre- or post- emergence herbicides were used to control weeds. Plots were cultivated as needed. Planting and other cultural practices followed were based on the recommendations of the Louisiana Cooperative Extension Service. Soil samples were collected immediately after the chickens were moved from the experimental plots and at harvesting time. Samples were also taken from unpastured spots around the study area as control samples. Mineral nutrient analysis was done at the Louisiana State University soil testing lab where an induction coupling plasma system was used to determine the base cations in the soil. Total soil nitrogen analysis was carried out at the Southern University Soil Laboratory using the Tecator Kjeltec system.
Plant growth measurements and yield data were collected for all the crops. Parameters measured included plant stand, plant height, canopy width, chlorophyll content, fresh yield and dry weight. Vegetative dry matter was determined by sub-sampling from the fresh harvest (center row of the three row plots) and drying the sample at 65 C for 24 hours. Insect damage was assessed qualitatively based on visual observation and the damage rated from 0 to 5 (no damage to total damage). Plant height and canopy width were measured immediately before harvesting. Leaf chlorophyll was measured in SPAD units during the reproductive stage of the crops using a Minolta chlorophyll meter. The climate data used in this study were rainfall, and daily maximum (Tmax) ) and minimum temperatures (Tmin)). Temperature data was used to determine the growing degree days (GDD) for the time of planting study.
Data were analyzed using the general linear models procedure of SAS with time of planting or fertilizer treatments as independent variables for the time of planting and fertilizer trials, respectively.
Eleven farmers were recruited for Objective 2. Of these, four actually reared birds. Three were successful with the birds and kept adequate records. These three planted a variety of vegetable crops behind the birds. One planting of pumpkins was destroyed by fungal diseases. Another farmer lost his crop to flooding. The remaining farmer kept good records of his birds and crops and showed a profit with both.
Producers were provided with funds to establish at least a 100-bird pastured poultry operation including construction of the pen(s), and purchase of birds and feed for the first batch. Equipment for processing was provided cooperatively to the groups. Farmers were provided with copies of the Pastured Poultry Record Book modified to meet the needs of the current project, for recording financial and production records. These data were used for evaluation of the pastured poultry project as a component of the small farm enterprise.
Each farmer selected the crops to be grown based on the current or projected operations. Funds for cropping inputs (fertilizer, seeds, pesticides, etc.) were provided. Each pen of poultry was placed adjacent to a control area of equal size where the farmer’s normal vegetable production practices were used in order to compare soil, crops and financial returns from both systems.
Because of the limited number of farmers who actually produced birds and the fact that only one was also successful at growing vegetables, a detailed economic analysis has not been possible.
Time of planting
In Fall 1999, despite receiving the lowest rainfall and GDD, the best response of mustard greens in terms of fresh yield, dry yield, plant stand and canopy width was obtained when the crop was planted 14 days after the birds were moved (D14). The lowest fresh and dry yields were obtained from D0 although there were more GDD than for D14. There was no evidence of burning from the chicken manure so the poor response may have been because the nutrients were not yet in available forms or were not dispersed through the soil. The lowest insect damage and most GDD were found with the late planted treatment, D21. Percent insect damage decreased as the temperature became colder later in the growing season. There was no significant difference in chlorophyll among the treatments.
Soil test results for samples taken at planting and harvesting show that in both periods, the control areas had lower nutrient levels than the pastured plots, indicating the nutrient contribution by pastured poultry. Soil pH seems to increase with pasturing and was significantly higher for pastured than for controls at planting. The highest value was seen on the D0 plots. There were no differences in pH at harvest. Differences in total soil nitrogen were not significant among the treatments but a higher difference between DO and D21 was observed possibly due to some leaching and volatilization loss of nitrogen that occurred in the 21 day planting difference. Mean percent nitrogen at planting and harvesting was 0.18 and 0.14.
Rainfall in Spring 2000 was not adequate so114 mm of supplementary irrigation was applied to the cucumber plots. Despite the differences in planting times, the plots matured for harvest at almost the same time. GDD decreased with planting dates, a result of the longer days as the season progressed. Harvesting started at almost the same time for all planting days. The highest chlorophyll readings, marketable yields and numbers of fruits per hectare were obtained from the D7 and D14 treatments. The lowest yield was obtained from D0 despite more GDD and more water (rainfall plus irrigation) than the other treatments. Total soil nitrogen levels before planting and after harvest were different, indicating plant use of nitrogen. Control samples taken before planting and after harvest had lower total nitrogen than the pastured plots, indicating the nutrient contribution by pastured poultry. Soil pH was significantly higher for the D7 treatment than for the D21 and unmanured control.
The highest plant stand, chlorophyll readings, marketable yields and numbers of fruits per hectare for squash planted in Spring 2001 were obtained from treatment D7. Numerically D0 gave the lowest yield. Although irrigation was employed after planting, heavy rain from tropical storm Allison caused excessive drainage problems, resulting in yellowing of the plant leaves. During the week of the storm, 482 mm of rain was recorded resulting in total water amounts of 588 to 604 mm for that growing period.
Although not statistically significant, planting 21 days after the birds were removed gave the highest yield of collards planted in Fall 2001 followed by D14. The lowest yield was obtained from D7. Immediately after the chickens were moved from the experimental plots, it rained heavily and made seed bed preparation difficult. Drainage problems and insect damage were the factors that could have influenced the results of this trial. D0 and D7 were planted on unsatisfactory seedbeds. The low yield of D0 and D7 may be attributed more to the moisture content of the soil than to the manure from the chickens. In general, short and stunted plant stands were observed.
Studies of soil fertility included squash in Spring 2000, cucumbers in spring 2001 and collards in Fall 2001. A Fall 2000 crop of mustards was lost due to inadequate fertility and insect damage.
In spring 2000 the highest total (9.67 t/ha) and marketable yields of squash were obtained from CM supplemented by conventional fertilizer. The highest chlorophyll and number of fruits per hectare were seen with CM supplemented by organic fertilizer.
In Spring 2001, the highest yields of cucumbers and number of fruits per hectare were obtained from the plots treated with CM plus conventional or organic fertilizer. Yields from plots treated with CM alone and CM supplemented with organic fertilizer were numerically the lowest.
For collards grown in Fall 2001, it was apparent that the CM and organic fertilizers did not provide sufficient nutrients for the crop. The plots treated with conventional fertilizer at the recommended rate produced significantly more dry matter and marketable yield than the other treatments although there was no difference in the number of plants per hectare.
Our farmer cooperators have been quite successful with their birds. For the three farmers for which records are available, the returns (exclusive of labor) were $3.73, $2.61 and $1.65 per bird. One farmer kept accurate time records and had a return of $2.30/hour to labor. The variations in income were largely related to selling price. One farmer sold at $7 per bird, another at $2.00/lb (which, with 4 lb carcasses, represented $8.00 per bird) and a third at $10 per bird. One farmer raised mustard greens after the birds and for those realized a return to labor of $3.76/hour. That grower noted that the mustards grown after the birds were less green than the fertilized mustards and suggested that fertilizer was required in addition to the poultry manure.
Educational & Outreach Activities
Pastured poultry as a fertilizer supplement for vegetable crop production. 2002. Ghebrieyessus, Y.T., O. Bandele and J. McNitt. Proc. of the Symposium of the Louisiana Plant Protection Association and Louisiana Association of Agronomists, April, 2002, Louisiana State University, Baton Rouge
Fertility evaluation of pastured poultry practices for vegetable crop production. 2003. Ghebrieyessus, Y.T., O. Bandele, J. McNitt, M. Berhane and R. Payne. Proc. 13th Biennial Research Symposium of the Association of Research Directors, No. 97.
Optimum planting days determination under pastured poultry: Practices for vegetable crop production. 2003. Ghebrieyessus, Y.T., O. Bandele, J. McNitt, M. Berhane and R. Payne. Proc. 13th Biennial Research Symposium of the Association of Research Directors, No. P180.
Pastured Poultry and Vegetable Record Book
It has become apparent during this study that, in southern Louisiana, the timing of the birds on pasture and the planting of the crops must be carefully coordinated to ensure that the crops are planted at the correct time. For example, if birds are placed on pasture at two to three weeks old in mid-April when the first good cover of grass is available, most farmers will not be able to plant vegetables until the birds are removed six to seven weeks later. This means planting in early June which is close to being too late for a number of crops. Similarly, if birds are placed on pasture in early September when it begins to get cooler, the crops cannot be planted until the middle of October which may be too late for winter gardens. In addition, planting a short season crop seven to fourteen days after bird removal may not leave enough time between manure application and crop maturity for organic producers. For example, the new organic standards require 90-120 days between manure application and crop harvest because of health concerns.
Farmers have seen the economic value of rearing pastured broilers, but many are reluctant to commit to the labor intensive home processing. Several of our cooperators have expressed an interest in rearing more birds. Two other producers have closely followed the project and, on their own, have begun producing pastured poultry although they are using the day range model. This model is very useful on the flat, high clay soils of this area where standing water after a rain is common. It also provides better protection against predators that the movable pen. We expect that more farmers will gradually become pastured poultry producers using the day range model.