Final Report for LS07-201
A multi-year study to evaluate the potential production of pigeon pea [Cajanus cajan (L.)] in the Southern United States was conducted from 2007 to 2011 in Northeast Texas. Pigeon pea is a warm-season legume crop grown for grain in the tropics and subtropics. More recently, it has been evaluated as a forage crop in the Southern U.S. because its drought tolerance and indeterminate growth cycle make it a good candidate for providing a source of forage from late summer to mid-autumn when other forage crops are less available. Pigeon pea is also a major pulse crop in some parts of the world, including India where current production is inadequate to meet demand, thus creating a potential export market for Southern U.S. farmers. Additionally, the rapid increase in the Indo-American population in large U.S. cities has created a local market for U.S.-grown pigeon pea.
On-farm studies were conducted to determine if pigeon pea could be direct-seeded into existing Bermuda grass pastures in the spring in order to enhance to pasture productivity in late summer and early fall. Results demonstrated that although pigeon pea will germinate and grow in an existing pasture, using pigeon pea in this way is not the most effective way to take advantage of its potential as a source of forage. Concurrent research in Oklahoma indicated that it is more effective to grow pigeon pea as a dedicated crop that should be grown to the flowering stage before allowing it to be grazed by cattle. Although pigeon pea is a drought tolerant crop, adequate moisture is needed for the first month after planting in order to achieve acceptable germination and seedling survival. Also, although pigeon pea can survive under conditions of low fertility with no supplemental fertilization, its overall growth and grain production is improved by supplying phosphorus fertilizer.
A runoff study was conducted to determine if Pigeon pea directly planted into existing pastures could reduce the total amount of stormwater runoff. Results indicated that reduction in storm water was dependent on pigeon pea type and population density. The Georgia-2 variety decreased storm water runoff when planted at a 123K plants/ha whereas the Georgia-1 had little effect. Results from the runoff study support the on-farm study in suggesting that pigeon pea has its greatest potential as a new crop for Southern farmers when planted in prepared soil with supplemental fertilization, regardless of whether the crop is being grown for forage or grain. However, use of pigeon pea for soil and water conservation remains a potential application for pigeon pea if the appropriate types and planting techniques can be identified. A potentially new use for pigeon pea identified by this project is its use as a combination vegetable and ornamental plant in urban landscapes where there is an increasing interest in urban farming, community supported agriculture, and community gardens.
- The overall objective of this research was to introduce pigeon pea as a low-input forage and grain crop in Northeast Texas and to investigate its growth and yield potential using a combination of on-farm and experimental field plot research. Specific objectives were:
1. Quantify the effects of pigeon pea planting strategies (plant variety, population density, and soil preparation) on water infiltration and runoff water quantity and quality. Evaluate the impact of pigeon pea on soil physical and chemical properties.
2. Evaluate the impact of pigeon pea grain crops on the depletion of soil profile moisture and the growth and yield of subsequent crops.
3. Demonstrate and evaluate the value of pigeon pea as a late season forage crop when intercropped with existing grass pastures or as a post-wheat-harvest crop. Determine if cattle will graze pigeon pea during its pre-flowering growth stage or if they are not attracted to the pigeon pea until it reaches its flowering stage. Determine if there are different patterns and preferences in the way cattle graze white seed versus brown seed pigeon pea varieties.
4. Explore the market for fresh pod and dried bean forms of pigeon pea in the Dallas-Fort Worth area.
It has been used for centuries as high-protein grain for human food (Whiteman and Norton, 1981) and forage for animal feed (Phatak, 1970, Wallis et al. 1986). Pigeon pea is the sixth most-common pulse crop in the world, but is still relatively unknown in North America. India is by far both the largest consumer and producer of pigeon pea (75%) where it is consumed primarily in a split pea form (dal). Myanmar is also a major producer of pigeon pea (14%) followed by several countries in East Central Africa (Kenya, Uganda, Malawi) (Fig. 1). On the Caribbean island of Hispañola (Dominican Republic and Haiti), pigeon pea is commonly consumed in a fresh green pea form. China is also rapidly becoming a producer of pigeon peas where it is used both as a food source and for hillside stabilization. In fact, it is the many versatile uses for pigeon pea that make it an attractive alternative crop for farmers around the world. Current trends in global population dynamics have created both local and export markets for pigeon pea grain.
In the Southern United States, pigeon pea can become a viable option for farmers due to changing population dynamics as well as increasingly common and unpredictable drought conditions. Drought conditions ranging from moderate to extreme have been commonplace in Texas and other parts of the Southern Great Plains, and the future outlook is for recurring drought conditions across the entire State of Texas (Miskus, 2011). At the time of this report (August 2011), 65% of the Southeastern United States is suffering from extreme to exceptional drought conditions. Texas is currently in the midst of the worst drought on record and 95% of the state is under extreme to exceptional drought conditions. Farmers are increasingly challenged to find enough hay or feed for their livestock and the sale off of cattle due to lack of forage and water has decimated the livestock industry in Texas and Oklahoma.
Pigeon pea is more tolerant of drought conditions than many other grain legumes (Snapp et al., 2003). It has a strong, deep taproot system that develops during the first few months of growth (Anderson et al., 2001) and which develops in diverse soil types ranging from coarse sands to alkali clays (Reddy, 1990). This makes pigeon pea well adapted to soil and climatic conditions in the Southern United States, where soils range from acidic to alkaline and from sandy to clayey textured. Rainfall in the Southern US can be sparse and infrequent, but also very intense and excessive. During periods of hot, dry weather, pigeon pea with a well-established root system is able to maintain vegetative growth (Anderson et al., 2001) when the growth of other forage crops, such as Bermuda grass, soybeans, and alfalfa has essentially stopped. The ability of pigeon pea to not only survive, but also maintain healthy vegetative growth during late summer in the American South, makes it a suitable candidate for filling the forage gap that occurs in late summer when grass rangelands are essentially dormant due to lack of soil moisture. Currently, southern farmers rely on off-farm sources of protein, such as dehydrated forage legumes and cottonseed meal, to meet the protein needs of their livestock during forage deficit periods, but this practice is less sustainable than relying on on-farm sources of protein. Phillips and Rao (2001) found that one unit of raw, cracked pigeon peas could replace 0.6 units of maize or 0.4 units of cottonseed meal. In addition to utilizing the pigeon pea grain as a food source for livestock diets, the entire aboveground biomass can serve as a forage source for livestock, either by direct grazing or as silage. Rao et al. (2003) evaluated two short-season pigeon pea varieties as forage sources in Oklahoma and concluded that early maturing pigeon pea varieties can fill the forage deficit period during late summer and provide a protein supplement for livestock.
A basic goal of a grazing program is to provide high-quality forage year-round to reduce costs of harvested forage, and/or concentrate feeds. No single forage crop has the potential to provide forage year-round. One of the traditional approaches to agricultural production in the southern Great Plains is based on production of stocker cattle, by grazing of winter wheat. Wheat pasture is grazed from late fall through early spring. Warm –season perennial grasses such as Bermudagrass and old world bluestems can provide forage during late spring and early summer. However, high quality forage is normally unavailable from late July through late November, when quality of summer perennial grasses have declined and winter wheat is not yet sufficiently established and productive for grazing. Therefore, additional forage resources with the ability to supply forage during the deficit period are needed for use in sustainable forage-livestock production system.
Ongoing drought conditions can also have implications for soil conservation. Climate models predict that a reduction in storm frequency, which is typical of drought conditions, would increase the erosion potential of soils, especially in areas that were previously characterized by a more humid climate (Istanbulluoglu, 2006). Typical grass rangelands can become very stressed during long periods without rain. When grass rangelands are stressed, they fail to provide adequate forage for livestock, and the decline in aboveground grass tissue exposes the desiccated surface soil to the shearing force of rain drops and surface runoff during the next rainfall event. Consequently, the potential for soil erosion can be great following a long period without rain. Overgrazing can also occur during drought periods, and this leads to soil compaction which reduces water infiltration and increases runoff once rainfall returns.
Pigeon pea has several properties that make it beneficial for soil conservation purposes. Since it is drought resistant, it continues to grow and develop an aboveground canopy when other crops are becoming dormant (Snapp et al., 2003). The extensive canopy protects the soil from the destructive force of rain drops during rainfall events. Additionally, the large tap root developed by pigeon pea has promoted its use as a “biological chiseler” for compacted soils or no-till farming practices in Latin America (Bot and Benites, 2001), Africa (Smolikowski et al., 2001), and China (Yang et al, 2001; Zong et al., 2001). Consequently, the beneficial effects of pigeon pea on protecting soil from erosion, reducing soil compaction, and increasing water infiltration make it an excellent companion crop for grass rangelands that suffer from the impact of drought conditions during late summer in the Southern United States.
Incorporating annual legumes into cropping systems of the southern Great Plains could provide producers with a variety of services including summer forage, biological N, or new grain crops. A number of annual legumes could be incorporated into cropping systems, but producers require knowledge and good management skills to ensure successful application of these practices. Critical knowledge gaps related to the effects of climate of the region on legume crops exist, including low and variable precipitation, high temperatures, and wind associated with summer months. Such climatic conditions can also create erosion problems used to produce cool-season cereals. Incorporating legumes into rotation as cover crops could help reduce erosion and increase soil organic matter during traditional fallow period, thus helping to improve overall soil quality (Biederbeck et al., 1993). However, information on water use by most legume species in the Southern Great Plains is limited, but needed to effectively double-crop legumes with wheat. Water use, water use-efficiency, and depletion of soil water differ among plant species, cultivars, and growing seasons. Rao and Northup (2008) reported 2.0 to 2.5 times more water use by soybean during wet years than dry years in the Southern Great Plains. In other regions, intermediate cultivars of soybean used more soil water than corn (Zea mays L.), during the growing season in India (Bargava et al., 1976). Information on water requirements of pigeon pea, particularly in combination with other crops, is necessary to understand the effect of including pigeon pea during fallow period of winter wheat under continuous winter wheat production system in the southern Great Plains.
On a world scale, pigeon pea is most commonly cultivated and harvested for human consumption. It is consumed as a dried bean, a de-hulled, split pea (called dal), or as immature green pods (Snapp et al., 2003). The rapidly spreading Indian population, where dal is a major food staple, has created increased demand for pigeon pear around the world. For example, in the Dallas / Fort Worth area of Texas, there are currently over 100,000 Indo-Americans in the Dallas/Fort Worth area (Harry Iyer, Dallas Indian- American Chamber of Commerce, Personal communication,). Currently, most ethnic specialized vegetables are imported into the North Texas area from California and/or Florida (Shailesh Shah-C R Produce Inc., Personnel communication). Given the likelihood of an increasing market for pigeon pea grain in the Southern United States, production of pigeon pea as a grain crop is another option for Southern US farmers. In some cases, it may be possible for farmers to cultivate pigeon pea both as a forage crop and a grain crop. In June of 2006, the government of India banned the export of lentils, such as pigeon pea, due to price stabilization concerns in India (Grossman, 2006). Pigeon pea prices in the United States have risen as much a three times due to this ban. (www.indusbuisness.com August 15, 2006). Harvesting immature pigeon pea pods is relatively labor intensive, but it may provide farmers with additional income from their pigeon pea crop while not excluding its use as a forage.
The purpose of this project was to introduce pigeon pea [Cajanus cajan (L.)], a drought-resistant and multipurpose leguminous crop into southern agricultural production systems in order to reduce the negative economic and environmental impacts of recurring drought conditions. Pigeon pea is uniquely suitable for this purpose because it can function as 1) a cover crop for improving soil and water conservation; 2) a drought-resistant late summer forage crop; and 3) a potential pulse commodity for urban markets.
Objective 1: Impact of range-seeded pigeon pea on stormwater runoff.
A series of 20 runoff plots measuring 3.04 m x 4.57 m at the Texas AgriLife – Research and Extension Center in Dallas were fitted with runoff water measuring and collection devices and used to determine the effect of various pigeon pea planting strategies on runoff water quantity and quality. The plots were located on an Austin silty clay loam soil with a slope of 2%. Five treatments were evaluated over the three-year period. In addition to a standard Bermuda grass control, the additional treatments consisted of two pigeon pea lines, Georgia 1 (GA-1) and Georgia 2 (GA-2) planted at a low population density of 123,500 plants/Ha and a high density of 247,000 plants/Ha using a 0.4 m row spacing. Pigeon pea seeds were no-till planted by hand into existing bermudagrass pasture that had been mowed to a 5-cm height. Seeds were inoculated with multi-strain Rhizobium and Bradyrhizobium spp N-fixing bacteria prior to planting (Anand & Dogra, 1997). No supplemental fertilization was supplied in order to evaluate the ability of pigeon pea to thrive under a competitive low-input pasture system.
During storm water runoff events, water and sediments from each plot were directed towards a 19 L container which was sufficient to contain all the water and sediments from an individual storm water event. Collection containers were checked after each major rainfall event and the contents of each container were measured to determine total runoff volume. The contents of the container were stirred and a subsample was removed in order to measure the total sediment content. Runoff samples from selected subsets of runoff events were also analyzed for concentrations of nitrate-N, ammonium-N, and orthophosphate. The amounts of water, sediments, and nutrients generated by each treatment were used to evaluate the effect of pigeon pea variety and population density on water infiltration and runoff characteristics. Runoff was monitored for three years.
Objective 2: Depletion of subsoil moisture by pigeon pea – USDA-ARS, El Reno, Oklahoma
Studies were conducted during summer fallow period in a continuous winter wheat production system at the Grazinglands Research Laboratory, near El Reno, OK (35040’ N, 9800’ W. elevation 414 m). Long-term mean maximum and minimum temperatures at this location during the June to September growing season are 360C and 200C, respectively. The long term average precipitation during the growing season is 425 mm (Table 1). Two pigeon pea cultivars were selected for this study. The cultivars were brown seeded Georgia-2 (GA-2) and white seeded Minnesota-8 (MN-8). Experimental plots (6, one acre plots for two pigeon pea cultivars and 3 half acre plots as fallow) were sprayed with a 1% Glyphosphate [N-(Phosphonomethyl) glycine] solution to control weeds. All plots received 23 lbs/acre P (in 116 lbs per acre of 18-46-0 dry fertilizer) one week before seeding. Seeds of GA-2 and MN-8 were inoculated with multi-strain inoculum and seeded at the rate of 25 lbs /acre with a row spacing of 24 inches. Cultivars were repeatedly planted on the same plots throughout the study period. Cultivars were seeded on May 20 in 2008 and 2009, and on June 01, in 2010. Soon after pigeon pea was seeded, (3 x 3 m) enclosures were installed in each treatment to prevent grazing. Neutron access tubes (1.2 m in length) were installed with a hydraulic soil probe in enclosures in all, grazing area and fallow (no pigeon pea) plots. Soil profile moisture was measured with neutron probe (Campbell Pacific Nuclear International model. 503 DR, Martinez, CA), at seeding, mid season and at termination of grazing, to determine soil moisture.
Objective 3: Demonstrate and evaluate the value of pigeon pea as a late season forage crop when intercropped with existing grass pastures or as a post-wheat-harvest crop. Texas AgriLife Research Center, Dallas, Texas and USDA-ARS Grazinglands Research Laboratory, El Reno, Oklahoma
3a - On-farm study: Evaluation of range-seeded pigeon pea in an existing Bermuda grass pasture – Dallas County, Texas
An on-farm study was conducted during the 2007 and 2008 growing season on Houston Black clay soil in Dallas County, Texas with the dual purpose of introducing pigeon pea to a practicing farmer and also to evaluate its ability to perform in an actively-grazed Bermuda grass pasture. Mr. Virgil Helm dedicated a 1-ha area of his Bermuda grass pasture for the on-farm study. Half of this area was used in 2007 and the other half in 2008. A third set of plots was planned for 2009, but a combination of weather and logistical factors prevented the establishment of those plots. Mr. Helm also provided the tractor and no-till planter used to establish the research plots.
The on-farm study consisted of three treatments, including: 1) Bermuda grass control, 2) Georgia-2 pigeon pea no-till planted on a 0.4-m row spacing, and 3) soybean no-till planted on a 0.4-m row spacing. Pigeon pea and soybean seeds were inoculated with a mixture of rhizobia and bradyrhizobia. No additional fertilization was applied in order to test the ability pigeon pea to compete with the existing pasture vegetation under low input conditions. Each treatment was replicated four times. Each plot measured 3-m wide by 100-m long. The entire study area was enclosed with an electric fence and protected from grazing by cattle so that the pigeon pea and soybean would have time to germinate and become established prior to grazing. In the first year of the study, the electric fence was removed from half the study area when the pigeon pea was approximately 35-40 cm tall. Stand counts were taken before and after grazing in order to determine if the immature pigeon pea plants were palatable to cattle and whether they would have a preference for soybean over pigeon pea. The same process was repeated with the other half of the plots when the pigeon pea was beginning to enter the flowering stage. During the second year of the study, we planned to remove the electric fence only for the early flowering phase of growth. However, failure of the fence allowed cattle to enter the study area before we could quantify growth, so only visual observations of their grazing preferences were possible.
During the first year of the on-farm study, a second set of plots was established in an adjacent pasture that belonged to Mr. Helm’s neighbor. The same treatments were used, but the plots were 50-m long rather than 100-m because these plots were not fenced-off and sub-divided. These plots left open to the grazing cattle so that the emerging plants would be immediately exposed to potential grazing by cattle. The purpose was to test the hypothesis that young pigeon pea plants would be unpalatable to cattle and they would avoid grazing the plants until they had reached a stage of growth that was more palatable. In actuality, given the option, cattle did not discriminate against the young pigeon pea or soybean plants and they were consumed shortly after emerging. Therefore this study was not repeated in subsequent years.
3b - Stock cattle grazing weight-gain study -- Grazinglands Research Laboratory in El Reno, OK.
The experimental design and other details were the same as that described under the methods for objective 2. For the grazing study, stocker cattle, weighing approximately 500 to 550 lbs, were selected for grazing, in 2008, 2009, and 880 lbs for 2010 grazing season. Rate of stocking varied among years mainly due to forage availability for stockers. Stocking rates were 3.0, 4.0, and 2.7 animals per acre in 2008, 2009 and 2010, respectively. Duration of grazing period also varied among years and was 59, 21, and 46 days in 2008, 2009, and 2010, respectively. End of grazing periods was determined when forage biomass was insufficient to maintain cattle weight. Stocker cattle were weighed at the beginning and end of grazing period in order to determine weight gains.
Objective 4: Marketing Study by the Greater Dallas Indo-American Chamber of Commerce (GDIACC)
The Greater Dallas Indo-American Chamber of Commerce conducted a study to investigate current and potential markets for pigeon pea. The report ranged from a broad overview of the major pigeon pea producing and consuming populations on a global scale, and then increasingly narrowed the focus to a national, regional, and finally, local scale. Specific topics covered by the study included: 1) the location and size of the major pigeon pea producing and consuming regions of the world; 2) the current and future trends in pigeon pea importing/exporting; 3) an estimate of the market demands for different forms of pigeonpea (e.g., green pea, dried bean, split bean, etc.) on a local, national and international level, and 4) a list of local retail/wholesale produce merchants in the Dallas area that currently purchase or would consider purchasing locally grown pigeon pea.
Objective 1: Impact of range-seeded pigeon pea on stormwater runoff.
Monthly rainfall totals for 2008 through April 2011 are shown in Table 2. Both 2008 and 2010 were typical years in terms of the amount of rainfall, whereas 2009 had higher than normal rainfall, especially during the months of September and October. Runoff volumes from the 13.9 m2 plots tended to be quite variable among the four replications which made statistical comparisons of treatment means impossible. Fig. 2 is a hydrograph that shows the average total runoff volume per rainfall event for each of the five treatments. Rainfall events from January 2008 to April 2009 generated small but measureable volumes of runoff. We determined that the berms surrounding each plot were not adequately containing all rainfall on the plot and consequently, the volumes only represented runoff from a portion of each plot. Therefore, berms were elevated, reinforced, and allowed to stabilize from the period from May 2009 through March 2010. Unfortunately, that period included two of the rainiest months during the study so we missed the opportunity to test the treatments under a period of intense rainfall. However, the renovated berms allowed us to collect accurate measurement of runoff events from April 2010 to the end of the project in April 2011 as indicated by the much larger per-event runoff volumes (Fig. 2).
Cumulative runoff volumes for the entire study period from January 2008 to April 2011 are shown in Fig. 3. These volumes are a more accurate representation of the effectiveness of the various pigeon pea variety x population density combinations. Even though the volumes measured before renovating the berms were much smaller than those measured after the berm improvements, their contribution to cumulative runoff was still valid and important for identifying which variety and population density were most effective at reducing runoff volume. Cumulative runoff volumes generally showed two apparent treatment effects. First, there was more total runoff from the GA-1 pigeon pea plots than the control and GA-2 pigeon pea plots regardless of population density. Second, total runoff from the GA-2 pigeon pea plots was less than runoff from the Bermuda grass control plots, and the reduction in runoff volume was greater for the 124K plants/ha population than for the higher 247K plants/ha density. This effect was apparent throughout the entire study period, although it was more pronounced after the berms had been renovated. The effect is somewhat surprising given the fact that the GA-1 pigeon pea was consistently 30 to 40% larger than the GA-2 plants in terms of height and aboveground biomass (data not shown). Apparently plant architecture plays a role in the pigeon pea plant’s ability to intercept rainfall before it reaches the soil surface. The smaller, more compact form of the GA-2 variety was more effective at intercepting rainfall than was the larger, more open canopy of the GA-1 type. Antecedent soil moisture is also a major variable affecting the rate and volume of stormwater runoff. Higher antecedent soil moisture contributes to greater runoff than lower moisture levels. Although we were not able to evaluate root structure and density, it is likely that the larger GA-1 plants had a deeper rooting system than the GA-2 plants. Consequently, they would have extracted moisture from deeper in the subsoil leaving more soil moisture near the surface. Conversely, the smaller GA-2 plants probably used more moisture from nearer the soil surface resulting in lower antecedent soil moisture prior to rainfall events. Lower antecedent soil moisture results in a more rapid initial infiltration of rainfall as well as increased total infiltration.
Objective 2: Depletion of subsoil moisture by pigeon pea – USDA-ARS, El Reno, Oklahoma
No significant differences were observed in the soil profile moisture content between grazed and fallow plots. However, significant differences were observed for year x treatment and time of the season x treatment interactions. In year 2008, the differences between fallow and pigeon pea cultivars were minimal, as compared to 2009 and 2010 grazing season (Fig. 4A). In 2009 and 2010, soil profile (0 to 65 cm) moisture at the end of the grazing season was 217 and 205 mm for fallow treatment as compared to 188 and 159 mm for GA-2, and 201 and 164 mm for MN-8, respectively. Cultivar GA-2 in 2009 and 2010 used slightly more soil moisture than MN-8. Profile soil moisture during early part of the growing season were similar among cultivars and fallow, mostly due to slow growth of cultivars (Fig. 4B). By mid to late season both cultivars used more soil profile water than fallow. Profile soil moisture during mid growing season decreased rapidly both in fallow and pigeon pea treatments, and could be attributed to warmer temperatures (evapo-transpiration in fallow plots), and uptake of water by actively growing pigeon pea. From mid to late growing season, fallow plots accumulated 36 mm as compared to 2 and 9 mm for GA-2 and MN-8, respectively. These results suggest that GA-2 and MN-8 were utilizing soil moisture from mid to late season, whereas fallow treatment added soil moisture to the soil profile.
Objective 3a - On-farm study 1: Evaluation of range-seeded pigeon pea in an existing Bermuda grass pasture – Dallas County, Texas
The ability to produce a viable stand of pigeon pea and soybean in an existing bermuda grass pasture proved possible, but probably not feasible based on two years of results from an on-farm study. In the first year of the study, planting was done in April when soil moisture was not limiting and plants emerged successfully (Fig. 5). The existing Bermuda grass pasture was mowed to a short height (5 cm) to facilitate planting, but no additional herbicide was used. One problem encountered with no-till planting directly into an existing pasture was the unevenness of the soil surface. The no-till drill was unable to maintain contact between all the planting disks and the soil. As a result, seeds were often deposited on the surface of the pasture and not inserted into the soil for many sections of rows. If possible, a light tilling of the Bermuda grass pasture with a disk might improve the planting surface without causing long-term damage to the pasture. However, such a practice may contribute to increased storm water sediment runoff from the pasture in the short-term and also increase the soils potential infestation from weeds.
Over-seeding pigeon pea and soybean into an existing pasture was likely to have a negative impact on the growth of the Bermuda grass due to competition for water and nutrients and shading. We compared Bermuda grass growth in the traditional pasture to its growth in the pasture over-seeded with pigeon pea and soybean. In August, which corresponded to approximately 100 days after planting, pigeon pea had no effect on growth of Bermuda grass, but soybeans had slightly decreased to biomass growth (Fig. 6). In the absence of the competing legume crop, Bermuda grass biomass continued to increase from August to October, aided by fall rains. Pigeon pea had an increasingly negative impact on Bermuda grass growth, probably due to competition for water as well as increased shading. Pigeon pea is an indeterminate crop, so it continues to increase is size and maturity through the months of August to October (Fig. 7). The effect of soybean on Bermuda grass biomass production did not change from August to October. Being a determinate crop, soybean growth is less active after August. In fact, other measurements showed that soybean biomass decreased from August to October whereas as growth of the indeterminate pigeon pea crop increased (Table 3).
One of the main purposes of the on-farm study was to determine if cattle would graze pigeon pea or ignore if in favor of grasses. Also, we wanted to determine if the stage of pigeon pea growth made a difference in the cattle’s preference. In early August, the bermuda grass, pigeon pea and soybean plants were all in the range of 0.58 to 0.64 m tall and pigeon pea had not yet started to flower. When cattle were introduced into the area, they indiscriminately grazed all three plant types showing no preference for one over the other. In fact, it was not possible to measure aboveground biomass 14 days after the start of grazing due to the general lack of harvestable plant material (Table 3). When the same test was conducted in October approximately one month after pigeon pea had initiated flowering, it was apparent that the cattle still did not discriminate against any of the three plant types. However, they did consume a greater fraction of those plant types (grasses and soybeans) that had smaller, less woody stems. However, pigeon pea plants were grazed down to the principal stem (Fig. 8). Later observations of the grazed area at 43 days after grazing, showed that pigeon pea plants were re-growing and sprouting additional tri-foliate leaves whereas the soybean plants were completely absent.
The second year of the on-farm study used the same plot design except that we omitted the August grazing test and decided to only allow cattle to graze the research plots after initiation of pigeon pea flowering. We experienced the same planting and germination problems that we had encountered the first year of the study. That is, the no-till planter was not able to uniformly place seeds in the ground resulting in spotty population stands. Seeds that were adequately placed into the ground germinated successfully. Unfortunately, the solar-powered electric fence protecting the study area from the cattle failed. The cattle entered the study area and completely grazed the research plots before we learned of the fence failure. Consequently, no data was collected the second year of the on-farm study.
Overall, the on-farm study proved that pigeon pea seeds can be no-till planted into existing pastures and produce a viable population of plants. However, the study suggested that this is not the best way for farmers to utilize pigeon pea as a forage crop due to several reasons. Without some sort of soil preparation, the uneven surface of most pastures will prevent proper functioning of the no-till planter and result in loss of seed and an inadequate population stand. Next, the area where the pigeon pea is planted will have to be protected from grazing cattle until the plants have reached an adequate size. If allowed to graze the area immediately after planting, the pigeon pea plants will probably not survive beyond the first trifoliate leaf stage. If the area is to be isolated from cattle, it is probably more logical and productive to grow the pigeon pea in a crop field whose surface is appropriate to regular or no-till planting.
Objective 3b - Stock cattle grazing weight-gain study -- Grazinglands Research Laboratory in El Reno, OK.
The amount and distribution of precipitation during the study period varied among years (Table 1). Total precipitation in 2008, 2009, and 2010 was 109, 91 and 92%,of the long-term 30-yr average respectively. Most of the precipitation received in 2008 was in August (50%), whereas 30 and 25% in August and October of 2009, and 40 % in July of 2010.
Average daily gain varied among grazing seasons. Weight gain by stocker cattle grazing GA-2 in 2008, 2009 and 2010 was 1.56, 1.87, and 0.92 lb per day, respectively. In contrast, stockers grazing MN-8 gained 0.92, 1.48 and 1.24 lb per day, in 2088, 2009, and 2010, respectively (Fig. 9). Total gain per acre by stockers grazing GA-2 were 277 lbs in 59 d of grazing period in 2008, 157 lbs in 21 d of grazing period in 2009, and 103 lbs in 46 d of grazing period of the 2010 growing season. Stockers grazing on MN-8 gained a total of 163 (2008), 125 (2009), and 142 lbs (2010) in the same number of grazing days as GA-2. These results suggest that average total gain by stockers in GA-2 was greater than MN-8.
Objective 4: Marketing Study by the Greater Dallas Indo-American Chamber of Commerce (GDIACC)
See attached GDIACC Market Report.
Educational & Outreach Activities
Sloan, J.J., Srinivas Rao, J.J. Heitholt, Sharad Phatak, and Russell Sutton. 2010. Evaluating the forage and grain potential of multiple pigeonpea varieties. ASA, CSSA. and SSSA International Meetings, Long Beach CA. Abstract No. 241-3
Ampim, John J. Sloan, Fouad Jaber, Raul I. Cabrera, Nick Ryan, Yingzhe Wu and Emily Guzik. 2010. Surface Runoff Water Quality from Multiple Best Management Practices in North Texas. ASA, CSSA. and SSSA International Meetings, Long Beach CA. Abstract No. 252-16
Metz, S.P., J.J. Sloan, S.C. Rao, D. Reger, S.C. Phatak. 2007. Pigeonpea: A versatile, drought-resistant crop for the Southern Great Plains. Agronomy Abstracts. ASA Madison, WI.
McKenney, Cynthia, Sue Metz, and Jennifer McCormick. 2008. Cajanus cajan as a Potential Ornamental for the Southern United States. 68th Annual Meeting of the Southern Region of the American Society for Horticultural Science. Dallas, Texas, February 2-4, 2008.
The most important result of this project was to clearly show that pigeon pea is a viable crop for southern farmers and to introduce the crop to farmers in Northeast Texas as well as urban residents and potential consumers in the Dallas Metropolitan area. Although pigeon pea is still far from becoming a common crop in the south, it is well on its way to becoming a crop that is known by both potential producers as well as consumers. Our research narrowed the potential uses of pigeon pea to those that are most likely to be used by farmers. The most practical and economical use of pigeon pea is as a forage crop that is planted in a dedicated field, and then grazed by cattle in early- to mid-autumn as it initiates its flowering stage of growth. One possibility for taking advantage of pigeon pea’s drought tolerance and indeterminate growth pattern it to plant the seed into wheat stubble as soon as possible after the wheat harvest and then allow cattle to graze the crop in late summer to early fall. This can be followed by tillage of the remaining post-grazed stalks in time for planting another winter wheat crop. However, this scenario requires that pigeon pea receive adequate moisture for germination after planting in order to achieve an adequate population stand. The risk of failing to establish a viable pigeon pea stand is considerably high given the increasingly unpredictable nature of the Southern US climate. However, the potential benefits could outweigh the risks if a cheap and abundant supply of seed can be made available to farmers.
A market analysis for dry pigeon pea bean indicated that the world demand currently exceeds the supply suggesting that pigeon pea grain should be a marketable crop. However, wholesale buyers are very limited making it somewhat difficult for farmers to sale their harvested beans. One possibility for a value-added pigeon pea product in the Southern US is the split-pea version that is the form most commonly consumed by the Asian Indian population. However, this process requires specialized equipment that would represent an up-front cost to farmers.
By growing more than 16 lines of pigeon pea in a highly visible community garden for two growing season, this project introduced the crop to a large pool of curious and potential consumers. This model can be replicated in other community gardens and thus begin to generate a demand for pigeon pea in the United States.
The greatest potential economic impact for pigeon pea on southern agriculture is related to livestock production. The summer of 2011 has been the driest summer on record for most of Texas. As a result of the severe drought conditions, increasing numbers of farmers have been forced to sale their cattle herds due to a lack of forage and water. For many farmers, this will be the end of their livestock-based livelihood. The size of livestock sales increased significantly as the summer progressed due to the prolonged effects of the drought. This research project was based on the premise that pigeon pea could provide a source of forage for livestock late in the summer and in early fall when most other forage sources, such as dryland, grass-based pastures, have become depleted or dormant, or they have already matured beyond the green vegetative stage of growth, such as corn silage or soybean hay. Our research showed that this is probably the most relevant use for pigeon pea in the Southern United States.
At this point, farmer adoption is still minimal, due primarily to a general lack of seed for large scale production. We are currently working with Texas A&M University at Commerce in Northeastern Texas to generate interest among farmers by evaluating additional lines of pigeon pea obtained from the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) and by increasing the amount of seeds available for planting. The increasing national interest in urban farming and community gardens had presented another opportunity for introducing pigeon pea to a market for both the dried bean and green pea. One potential use for pigeon pea that was identified as a result of this project was growing of pigeon pea as both a food crop and an ornamental plant in urban landscapes.
Areas needing additional study
Knowledge of pigeon pea in the United States is limited, but fortunately it has been thoroughly researched at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) in India. Our research was focused on answering straightforward and practical questions on how farmers in the Southern United States might best utilize pigeon pea in their agricultural practices. Although we worked primarily with two early-maturing varieties of pigeon pea developed by Dr. Sharad Phatak in Georgia, our evaluation of another 20 pigeon pea lines obtained from ICRISAT demonstrated that there is great variability in the pigeon pea germplasm. Future research should focus on identifying the most appropriate pigeon pea germplasm for the Southern United States. Additionally, our research identified that certain pigeon pea lines might be candidate biomass crops for biofuel production. Initial screening of pigeon pea germplasm identified several slow-maturing lines that produced up to 20 Mg/ha of total aboveground biomass.