Final report for ONC16-014
Pasture based dairying in Missouri represents over 40% of the total dairy cows in the state and continues to expand. Most operations are low-input type systems which means the goal is to provide the highest percentage of dry matter pasture intake in a cow’s diet as possible for as many days as possible. This could mean as much as 85-100% of the diet is pasture for short windows of time. Ideally in a grazing system, growth rates, or the amount of dry matter pasture grown per day per hectare across the farm would be fairly consistent throughout the grazing season. However in a continental climate such as Missouri this is not reasonable or expected. Growth rates can range from zero to over 100 kg per hectare per day. Typically operations need 35-45 kilograms of pasture growth per hectare per day on average across the farm. This results in periods of deficits and surplus throughout the season. Deficits usually occur during periods of heat stress and reduced rainfall during the summer. Producers initially began evaluating and implementing irrigation more as an insurance policy during these severe periods rather than as a tool to grow more forage. However, interest grew in how much forage could be grown during inclement weather and the cost to produce it. Optimizing and timely utilization of forages in grazing systems are critical for cash flow, profit and sustainability. Irrigation is a novel approach to maintaining forage growth in Missouri however we had little data or experience to draw on to make informed decisions.
Producers requested more information on irrigation efficiency and cost effectiveness of their systems across several forage species. It was determined the university would measure weekly forage mass of several paddocks on each farm. Each paddock would have a portion that would be irrigated and an area non-irrigated to try and reduce management and any soil type differences. Paddock typically were 2 to 4 hectares in size. Two to three times during the growing season, calibration measurements and clippings occurred to determine forage dry matter prediction equations. Producers provided weather data as well as irrigation and grazing dates. Data was compiled and analyzed via ANOVA evaluating specific points of the growth phase from grazing event to next grazing event.
There appeared to be a trend of additional forage grown for all species (Alfalfa; P=0.24, Perennial Ryegrass; P=0.11; Tall Fescue; P=0.29). Crabgrass was not included as the producer did not need additional forage growth and did not irrigate. Irrigation for alfalfa was sporadic due to the system type and labor required. The irrigated grasses had similar annual increase in dry matter yields per grazing event (Perennial Ryegrass; 125 kilograms per hectare; Tall Fescue; 134 kilograms per hectare) while alfalfa (86 kilograms per hectare) was slightly less possibly due to a deeper root system and more sporadic irrigation events.
Costs for additional dry matter forage for alfalfa, perennial ryegrass and tall fescue were $0.20, $0.43 and $0.30 per additional kilogram grown above the non-irrigated forage.
Discussion groups on various farms were given updates as they study progressed. Unfortunately for the study but fortunate for the producers, both years had adequate rainfall so a true value of irrigation’s potential for forage growth was not tested. A positive was a trend was noted for all forage species however it may not be cost effective. Prime alfalfa hay could possibly cost $0.26 per kilogram of dry matter delivered. The producer would have to make a decision, if the costs presented here are true every year, if the investment, labor and other costs are cost-effective for their system.
Producers learned the cost of yield with sporadic irrigation practices. If the investment is made, the main costs after will be labor and certainly power (electricity, propane, natural gas) to run the systems. In a year with adequate rainfall, these costs may outweigh the cost of prime alfalfa. The main learning point was the following of evapotranspiration rate for the week. This allows the producer to know how much water needs to be applied each week to keep soil water holding capacities from being depleted resulting in reduced forage growth.
For these two years of irrigation observation, irrigation’s costs would be similar to the cost of purchasing prime alfalfa. The decision the producer makes is if the total investment for irrigation outweighs the total cost of purchased alfalfa year after year. These producers we believe would say yes, not only as an insurance policy as stated before but also for fringe benefits of forage re-establishment but also possible cow cooling during heat stress.
Objective 1: provide information for producers to develop a pasture system that enhances their lifestyle while securing long-term sustainability
- Eight discussion group/pasture walks were held over the grazing season in 2016 and 2017. Facebook group page was formed in early 2016. Information regarding pasture management as well as preliminary information from the irrigation study were shared with producers by the PI of the study as well as host producers. Information was shared through these avenues and a summary of the data will be provided at the end. Producers have already requested if the trial can continue further past year two in order to gather more information under different weather situations.
Objective 2: Determine cost-effectiveness of various irrigation systems across different forage systems
- Data on power usage and cost, time, capital expenditure was collected and compiled in report.
Objective 3: Determine water use efficiency between irrigation species and forage species
- This is ongoing. Raw forage data will be analyzed and confirmed via the forage neural network system and correlated to total water (rainfall and irrigation) as well as just rainfall to determine forage species efficiency. Additional data is needed to address this modeling as none of the forage species were stressed significantly.
Objective 4: Develop webpage for farmers to plug and play various scenarios to determine combinations best for their systems
- Data from this project is updating this model to allow producers to make informed decisions regarding irrigation usage as well as forage or irrigation type. Discussions have already been had with university economists to assist in the development and updating of this tool.
SARE-report-PP1Six pasture based dairy farms utilizing one of three types of irrigation (center pivot, spider, pods) and 4 species of forages (perennial ryegrass, tall fescue/clover, alfalfa or crabgrass) participated in the study. The main objective was to provide information for producers to develop a pasture system that enhances their lifestyle while securing long-term sustainability. This entailed measuring forage response to irrigation, the type of irrigation, forage species response and the costs associated with irrigation.
Three to six paddocks on each farm were measured weekly beginning mid-May and ending October 30. Farms were measured weekly using sonar sensor technology mounted to an ATV. Records on irrigation dates, water applied, grazing/harvest events and rainfall were provided by the producer. Treatments of irrigation and non-irrigation occurred in each paddock as suggested by the producers. For center pivot irrigation, this consisted of only using paddocks that had both irrigation within the irrigators arc and dryland outside the arc of irrigation. For the other types of irrigation, a specific area within a paddock was designated by the producer to not be irrigated during the study. Measurements were taken separately on the irrigated and non-irrigated portions of each paddock weekly. Fertilization practices were the same for both irrigated and non-irrigated forages.
Measurements and Calibration:
Forage measurements were taken weekly on each farm, paddock and treatment using a sonic sensor mounted to the front of an ATV bike (Figure 1). The sensor emits sound waves and measures the time elapsed for waves to return. A small amount of elapsed time corresponds to a short travel distance and “tall” grass while a longer elapsed time would indicate “short” grass. The amount of data collected is large with the sensor recording data up to 50 times each second. Forage height is measured in millimeter of height from the ground.
Calibration of these heights are critical for accurate prediction of forage mass (Figure 2). During calibration, forage is measured in diverse locations across a pasture, including areas with short, medium and tall forage heights. This provides range needed for proper calibration. Forage from these measured areas is harvested with a machine, dried and weighed. We relate the amount of forage produced, to the height previously recorded by the sensor. These sensor heights and dry matter yields for the areas cut and measured are used to develop trend lines and equations for use across the farms.
Our results show a strong linear relationship exists between actual yield and predicted yield modeled from the sensor height and other environmental parameters (Figure 3). That the relationship is retained throughout the range of the data is important.
There were points in time across all farms irrigation events did not occur. Each forage mass measurement was coded according to treatment (irrigated vs non-irrigated) as well as if the treatment actually occurred. For example if a paddock area was supposed to receive irrigation but did not between grazing events, it was re-coded along with its non-irrigated treatment mate within the paddock and eliminated from the analysis. This allowed the analysis to evaluate the true value of irrigation rather than have the possible masking effects of an irrigated treatment area that did not get irrigated being included in the analysis. Each forage mass measurement was also coded relative to the growth phase in time. Measurements that occurred immediately prior to a grazing event were coded “Pre” and the subsequent measurement week “Post”. Subsequent weeks following a “Post” event were coded based on number of weeks past a “Post” event (week 1, week 2 and so on until a new grazing event occured). This evaluation should represent a generic growth phase of a forage. “Pre” would represent the amount of forage dry matter present for cows to graze at turn in; while “Post” represented the amount of forage remaining when cows left the paddock. Each coded point in the growth phase was analyzed via ANOVA using JMP SAS. There was no year to year interaction so all data was pooled for the analysis.
Optimizing and timely utilization of forages in grazing systems are critical for cash flow, profit and sustainability. Rainfall in Missouri as well across other areas of the fescue belt can be sporadic and impact forage pasture growth forcing producers to supplement more expensive harvested forages or grains/commodities. Irrigation is a novel approach to maintaining forage growth in Missouri with little data or experience to draw on to make informed decisions.
For an irrigation trial attempting to quantify various forage species yield effects to irrigation treatment, the years 2016 and 2017 were not ideal candidates. When evaluated against the five year average, it is apparent 2016 was abnormal in terms of soil available water at the 250 mm depth (Figure 4. Top Panel). Year 2016 in southwest Missouri was coined a New Zealand summer with its frequent rainfall and temperate temperatures. Year 2017 was similar but with less frequent and larger amounts of rainfall per event. Data in figure 4 is reported as weekly sum for water holding capacity, rainfall and evapotranspiration. Water holding capacity is reported as a percentage of capacity due to the various capacities of soil types across and within farms in the study. Although both treatment years were advantageous to producers participating in the study, it did make comparisons of systems and forage differences more difficult. However, we believe there were certain areas conclusions and recommendations could be made for producers interested in pasture-based irrigation.
Forages: Irrigated versus non-irrigated
Crabgrass: Crabgrass (Digitaria ciliaris) is generally considered to be a high producing (greater than 10 tons per hectare), and moderate to high-nutritive value forage (RFV greater than 150). Crabgrass is a summer annual forage established by seeding either through planting or managed to produce volunteer seed year to year. It is used in double-cropped systems following winter annuals such as triticale, wheat, annual ryegrass or cereal rye.
This producer uses a variety of crabgrass known as Red River developed by the Noble Foundation in Oklahoma. Crabgrass on this farm is double cropped with annual ryegrass planted the first week of September and terminated early May so crabgrass can be planted (5.5 kilograms PLS per hectare) mid-May. Crabgrass is terminated late-August for the establishment of annual ryegrass.
The producer elected to not irrigate crabgrass either year due to adequate dry matter forage growth on the grazing platform exceeding pasture feed demand (pasture dry matter intake per cow X stocking rate; 16 kilograms per cow pasture dry matter intake X 3 cows per hectare = 48 kilogram pasture feed demand). This indicates the producer needed to grow 48 kilograms per day per hectare (growth rate) across the grazing platform to maintain an equilibrium of farm pasture cover (average amount of dry matter forage per acre). In this case the producer exceeded this threshold the majority of weeks in both years, thus the decision to not irrigate the crabgrass. There were cases crabgrass forage daily growth rate exceeded 222 kilograms per day with cows returning to the paddock to be grazed every 10-14 days. In the few cases where growth rate slowed due to lowered soil available water, the producer would prepare to set up the irrigation system, however a rain event would occur prior to set-up and the irrigation event would be postponed. This producer utilized a pod-like irrigation system (K-Line; Figure 5)
Crabgrass average cover was typically greater than 2100 kilograms per hectare across both years (Figure 6). In 2016, soil water availability at the 250 mm soil depth dropped below 10% during the week of July 22. Average cover declined from the previous week but stabilized after rain events the following weeks. In contrast, in 2017, soil water availability declined to less than 10% for the weeks of July 15 and 22 and did not rise above 50% until the week of July 29. Growth rate and average cover did not recover to the levels of the previous weeks. Crabgrass has indeterminate growth characteristics making seed and leafy forage throughout its growing season. Observation has shown it tends to lean more to seed development later in the growing season. This may explain the lower average cover and growth rate for both years when soil available water was adequate.
As a side note, Figure 7 shows a distinct advantage for irrigation when establishing a new seeding. This picture was taken the fall of 2015. Annual ryegrass was planted September 1 and irrigated with the K-line system (50 mm). There were areas that the producer was unable to irrigate. On October 15, the irrigated annual ryegrass measured over 3000 Kg ha-1 while the non-irrigated areas measured less than 1000 Kg ha-1. This demonstrates the importance of moisture during the establishment stage as well as speaks of the value of irrigation in establishing a new pasture that is not captured in the current costs and benefits described later in the paper.
Alfalfa: Alfalfa (Medicago sativa), is a long lived perennial legume well known for its high yield and nutritive value (RFV greater than 180). It is one of the most commonly fed forages fed to lactating dairy cows. Growth patterns in grazing systems in southern Missouri tend toward grazing starting in early May and ending at the first hard freeze in mid-late October.
This was the only farm utilizing alfalfa as a component of their grazing system (Figure 8). Varieties utilized were selected for high traffic use to reduce crown damage and improve stand longevity. To reduce incidence of bloat, cows grazed alfalfa to a stubble height of 100 to 150 mm. This stubble held few leaves and consisted mostly of stem. During milking, cows would enter the stubble area of the paddock in groups of 20 cows allowing them time to consume effective fiber from the alfalfa stubble. On completion of milking, the entire herd would receive a new break of fresh alfalfa. The stubble area would be mowed to a residual of 44-60 mm to be reset for new growth. This practice has resulted in a very low incidence of bloat.
This farm utilizes a low pressure traveling gun type system (Spider) to apply up to 35 mm of water per full pass (Figure 9). The system is driven by water propelling the irrigator arms driving a ratchet to pull the spider attached to a cable anchored at the opposite end across the field. The water line source is pulled behind the Spider. This design led to the conclusion it should only be used once per grazing event in alfalfa paddocks due to the water line pulling/pushing over alfalfa plants. Alfalfa was intended to be irrigated within 2-3 days after the mow-down of the residual. As on all dairy farms, best intentions do not always means best results as other aspects of the farm could push aside the critical irrigation period for alfalfa. There were times irrigation events did not occur, although needed, when other farm matters took precedence. These periods were eliminated from the analysis.
In figure 10, top panel, the growth phase with Pre and Post harvests are shown. On average, irrigated alfalfa received 76 mm of irrigation across the season averaging nearly five grazing harvests per season. Irrigated alfalfa consistently yielded higher dry matter mass per hectare than non-irrigated. Irrigated alfalfa yields were 11, 18, 22, 19 and 8 percent higher than non-irrigated for weeks post grazing 1, 2, 3, 4 and for Pre grazing events, respectively. This resulted in an 86 kilogram per hectare (P=0.24) of forage mass advantage for the irrigated alfalfa at the measured Pre grazing week. Week four suggests 156 kilogram per hectare advantage for irrigated alfalfa. This larger advantage when compared to the Pre grazing week could possibly be a masking affect occurring during the pre-grazing week. There were measurement weeks where the producer was strip grazing the alfalfa when a measurement occurred. This would result in a portion of irrigated alfalfa had been grazed while the entire area of the non-irrigated alfalfa was untouched resulting in a lowered measurement of the irrigated alfalfa. The producer also indicated there were times alfalfa prior to grazing was beginning to layover due to a higher height which would result in a lowered mm height when compared to the previous week. It was indicated this typically occurred to the irrigated forage and not the non-irrigated. This indicates the advantage may well be closer to the 156 kilogram per hectare advantage for irrigated alfalfa rather than the 86 kilogram per hectare.
There were obvious times irrigation by observation demonstrated a striking advantage to the non-irrigated area (Figure 11). These times were rare during the 2 year trial and shows the need for additional research to determine the actual value of irrigation on pasture systems.
Perennial Ryegrass: Perennial Ryegrass (Lolium perenne) is well known across the dairy grazing world as a premiere cool-season perennial grass. It is noted for its ability to respond to grazing pressure, high yields and superior nutritive value. However, in southern Missouri, persistence can be an issue with some varieties needing to be reestablished after three seasons. Producers involved in this study have selected a variety (Albion) from France with a similar latitude as southern Missouri (Figure 12). This appears to have added one to two seasons before reestablishment must occur. Grazing management is similar to tall fescue with pre-grazing target heights of 100 mm and post-grazing residuals of 35 to 50 mm. Perennial ryegrass was irrigated under center pivot systems (Figure 13). The use of center pivot irrigation made irrigating decisions as a mere flick of the switch or push of a button will set irrigation in motion. Labor was not an issue if irrigation would occur or not as it appeared to be on the other systems.
In figure 10, middle panel, the growth phase with Pre and Post harvests are shown. On average, irrigated perennial ryegrass received 254 mm of irrigation across the season averaging over six grazing harvests per season. Irrigated perennial ryegrass consistently yielded higher dry matter mass per hectare than non-irrigated. Irrigated perennial ryegrass yields were 7, 35 and 9 percent higher than non-irrigated for week 1, 2 post grazing and for Pre grazing events, respectively. This resulted in a 125 kilogram per hectare (P=0.11) of forage mass advantage for the irrigated perennial ryegrass at the measured Pre grazing week. Week four suggests 156 kilogram per hectare advantage for irrigated perennial ryegrass. A masking affect again may be occurring due to perennial ryegrass being grazed consistently between week 2 and week 4 post grazing event and the weekly measurement unable to capture the true Pre grazing value.
Tall Fescue: Tall Fescue (Schedonorus arundinaceus) with white clover (Trifolium repens) is a long-lived, comparatively deep rooted, perennial bunchgrass. Being a cool season forage, it is typically grazed from late March through late November in southern Missouri. High summer temperatures with inadequate rainfall can slow growth during the summer. This forage is known for responding to grazing pressure as well as persistence. These producers use a novel endophyte soft-leaf variety (BarOptima Plus E34) to avoid fescue toxicity. Tall Fescue was irrigated under two systems, Spider and center pivot. Grazing management on both farms generally consisted of a pre-grazing target height of 125 to 180 mm and grazing to a 50 to 80 mm residual so adequate water soluble carbohydrates from the stubble were available for regrowth.
In figure 10, bottom panel, the growth phase with Pre and Post harvests are shown. On average, irrigated tall fescue received 117 mm of irrigation across the season averaging 5.3 grazing harvests per season. Irrigated tall fescue consistently yielded slightly higher dry matter mass per hectare than non-irrigated. Irrigated tall fescue yields were 7.6, 0, 6.5 and 7 percent higher than non-irrigated for week 1, 2 and 3 post grazing and for Pre grazing events, respectively. This resulted in a 134 kilogram per hectare (P=0.29) of forage mass advantage for the irrigated tall fescue at the measured Pre grazing week. There does not appear to be a masking effect for tall fescue possibly due to time measurement was obviously before or after a grazing event at all times as compared to the alfalfa and perennial ryegrass.
Producers supplied information regarding set-up and installation of their systems. In general, costs were $3100-3800 per hectare for center pivot, $2600 per hectare for the Spider and $1500 per hectare for the K-Line system. However, these numbers can be diluted or exaggerated depending on the farm. For instance, some farms required 3-phase power and others did not. The amount of dirt work required or movement of buildings or existing power lines added costs as well. It appears the major factor driving cost per hectare, is the number of hectares a system can reasonably irrigate consistently from the water source. The producer using the K-Line system had an existing water source and did not require the cost of drilling a well or constructing an impoundment. The zero cost of not developing a water source resulted in this system being half the cost of the other systems. However, the water supply here is limited which forces the producer to make critical decisions on if and when to irrigate.
In contrast, the higher cost center pivot may rely on deep well systems capable of nearly 7000 liters per minute. This system may be able to irrigate up to 200 hectares but requires a cost of 25-30 percent of the total cost solely for the water source. If wells are not capable of producing this amount of water, the number of hectares can reduce significantly thus raising the cost per hectare. On a different farm, cost were less for their center pivot as the water source is pumped from a river but costs were increased due to lay of the farm requiring some pivots to “windshield wipe” thus reducing the number of hectares the pivot is capable of irrigating.
The Spider system cost again was mostly driven by the cost of water source as well as limited by the number of hectares the system was capable of irrigating efficiently. Requiring around 3000 liters per minute for the system, the well, pump and water lines were approximately 40 percent of the total cost. This system utilized three Spider type irrigators. As stated earlier, the labor involved in the daily shifting of the irrigators to new areas in combination of the day to day duties of the dairy made irrigating inconsistent, especially with the small windows of opportunity for alfalfa.
The dairy team has begun to develop an irrigation worksheet to evaluate various systems. As we continue to accumulate more production and financial data this “plug and play” worksheet will be updated (http://dairy.missouri.edu/grazing/resources/).
Costs for additional dry matter forage for alfalfa, perennial ryegrass and tall fescue were $0.20, $0.43 and $0.30 per additional kilogram grown above the non-irrigated forage. Fertilization costs were the same as treatments were within the same paddock so were not included in the cost structure.
Conclusion: The years 2016 and 2017 were not good years to evaluate cost-effectiveness of irrigation as moisture was never consistently in severe depletion of water at the 250 mm soil depth as historically it can be for extended periods of time (Figure 4). Regardless, there appeared to be a trend of additional forage grown for all species (Alfalfa; P=0.24, Perennial Ryegrass; P=0.11; Tall Fescue; P=0.29). Alfalfa has a deeper root system compared to the other species, especially perennial ryegrass, and could be drawing moisture from a deeper depth than reported. Additionally, irrigation for alfalfa was sporadic due to the system type and labor required which could have had an effect as well. The irrigated grasses had similar annual increase in dry matter yields (Perennial Ryegrass; 125 kilograms per hectare; Tall Fescue; 134 kilograms per hectare) while alfalfa (86 kilograms per hectare) was slightly less again possible due to a deeper root system and sporadic irrigation events.
Costs were higher for perennial ryegrass due to nearly three times the amount of water applied. This raises the question if perennial ryegrass would have the same yield if the irrigation was reduced to the amount tall fescue received. Perennial ryegrass has a shallower root system compared to tall fescue and certainly alfalfa. Higher amount of water may be required. This needs to be further investigated.
When producers begin to entertain the investment of irrigation on pasture, they should adopt a system that fits their needs and goals as well as fits the parameters the system is capable of managing. Hectares irrigated and water source availability can drive the cost per hectare and should be listed as top areas of investigation if irrigation is a viable option for the farm. Secondly, the producer must be honest and determine if the labor resource is adequate to efficiently operate the system. Lesser cost per hectare can be erased if the system is not adequately utilized thus possibly reducing increased forage mass.
Not identified in this report is the added benefit irrigation can have on the establishment of new forages (Figure 14). Pasture out of production costs money not only in the investment of the establishment but the loss of potential production. This is evident in Figure 7 where irrigated annual ryegrass yielded 2000 Kg ha-1 more forage mass than non-irrigated in less than 45 days after establishment. A second potential benefit, is the use of the irrigation system to cool cows during periods of heat stress. It was difficult to measure as cows were not divided into groups cooled and not cooled, but research has shown advantages of cooling cows with less lost milk production as well as reduced embryonic loss.
This report shows additional research needs to be done on the value of irrigation. Producers have realized the importance of monitoring soil moisture conditions either via soil moisture probes (calibrated correctly) or following weekly evapotranspiration rates and irrigating accordingly. Questions that need to be answered are the amount of water needed to be applied across species. Power cost to apply water help drive the cost of efficiency of forage production. Power costs in this study could be as high as $14 per 25 mm water applied per hectare. Producers should know the proper amount and correct timing of irrigation to maximize efficiency of their system.
Educational & Outreach Activities
Monthly discussion groups in south central and southwest Missouri were held. Discussion groups consist of a general area of topic held on individual farms. Typically a farm-walk occurs as well. Owners or managers of the farm lead the discussion with informal questions and comments from the general audience usually consisting of other dairy farmers and occasionally beef operations. Monthly participation (15-60 people) ranges widely depending on weather conditions, distance to be traveled and interests in the topic. Irrigation and this irrigation study were discussed as side topics and updates. The summer of 2018, a formal report and presentation will be given to the producers at a special discussion group focusing on irrigation.
An Excel worksheet is being developed and updated as new data becomes available to assist producers in determining their potential costs and projected costs to produce additional forage via irrigation. http://dairy.missouri.edu/grazing/resources/
Data from this project was presented at the NC SARE Our Farms Our Future conference, in St. Louis. (Figure 15).
Current plans are to evaluate data and develop a prediction model for water applied with weather conditions and forage species type. This type of modeling will require range of results which we did not obtain in this study due to cooler than normal temperatures and above average rainfall for the irrigation season. It is hoped with additional data collection a reliable, easy to use, model can be developed and published in the Journal of Crop Science.
The main key for irrigation is understanding the soil's water holding capacity and the amount of water needed to be applied weekly to ensure this is not depleted to where it impacts forage growth. Producers began monitoring ET rate from their local weather apps and adjusting irrigation rates accordingly.
Producers saw that not all forages will perform to their expectations. Irrigation of cool season forages may not be the most efficient use of irrigation compared to warm season forages. For instance the producer using crabgrass did not need to irrigate at all for both seasons due to its efficient use of available water. However, each farm has its own goals and capacities. Some producers want to utilize a single forage species for ease of grazing management. A warm season component in their system will complicate grazing management. Their goal is for the cool season grass to survive and grow slowly through the summer months and be ready for steadily increasing growth growth in the fall.
Successful grazing operation in Missouri combine adequate pasture dry matter intake and forage nutritive value to drive milk production. It is commonly stated if we stake care of the grass the cows will take care of the milk. This means in our systems pasture growth rate needs to be consistently around 40 kilograms forage dry matter per hectare per day and nutritive values about 18% crude protein (CP) and metabolizable energy (ME) above 11. This requires actively growing forage plants. The two years of study did not put the stresses on the systems as we normally would see. However there were observations that appeared beneficial besides the trend towards increasing forage dry matter mass as previously reported. First, although this was not a design for measurement, it appeared there was less weed invasion in the irrigated areas compared to the non-irrigated. This may be due to less desired plant loss and open ground in the irrigated areas. This needs to investigated further as may mean less use of herbicide in controlling broad leaf weeds in pastures. Second, as stated with the first point, less open ground tended to be observed with the irrigated ground. As this was only a two year study we were not able to determine stand longevity. However, it could be deduced with less open ground, less desired plant deaths were occurring each year thus adding additional years to stand persistence. Lastly and perhaps most important was usage of water. Producers after seeing response rates across other farms and other species with varying irrigation amounts began to see they may be needing to be more specific in their irrigation methods. This may be more irrigation amounts at times and less at others. However with water becoming an ever increasing resource we need to value and protect, the irrigation protocols and methods to ensure irrigation efficiency will become even more important. We are already seeing these producers use ET rates and soil probes to help determine amounts and timing of irrigation.
The producers understand the importance of this project to determine the cost effectiveness of irrigation for them personally but also industry wide. Grazing systems are becoming more popular across the country and the public’s positive perception of grass-based products (meat, milk, eggs) appears to be increasing daily. Systems need to be designed so these products can be efficiently produced at a reasonable price for the public and allows producers to have a successful and sustainable lifestyle. Irrigation will be a part of this system in many parts of the country. More information is needed to more directly account for forage mass growth (additional measurements at pre and post grazing events). More information is needed on the correct amount of water needed for each species. This would more than likely could entail plot research where various plots receive varying amounts of irrigation to determine the optimum amount of water needed. The project and producers thank the NC SARE for funding this project and important information for the producers.