There is a saying, “You can’t manage what you don’t measure,” and this holds true for pasture as well as crops. There are many ways to monitor and keep records of pasture yields and grazing activity. Personally, I am a fan of whatever recordkeeping system works for the individual farmer, as it has to be efficient, straightforward and provide useful information to be worthwhile.
One tool I have seen used with success is the Holistic Management Grazing Planning Chart. This tool was initially developed by Holistic Management International as a part of their overall decision making framework for farm planning. Troy Bishopp, of the Madison
County Soil and Water Conservation District in central N.Y., was able to bring the chart to the masses through a Northeast SARE grant, with the help of a network of service providers who then reached out to individual farmers. In 2013, I began distributing these charts so farmers who
were interested could try them out and evaluate their usefulness.
On the surface, the chart is just a large sheet of paper with a lot of rows and columns that form a grid. This grid is really a “year-at-a-glance” calendar that can be a powerful planning and recordkeeping tool. With a simple daily activity of filling in a box that corresponds to the day and
the field or paddock where the animals have moved, a pattern forms providing a visual record of the entire season laid out at once. With this chart, there is no flipping pages back and forth in a calendar to figure out what animals were where and when. I personally like being able to look at a chart and see how many days since I last grazed a given area, and it helps me readjust my plan. At the end of the season, I find it informative (or in the case of last summer, depressing) to see how many times I was able to graze a given field. For experienced grazers, try planning a month ahead by filling in the chart in pencil and then have fun seeing how close you were.
This will be the fifth year distributing grazing charts and I am seeing farmers track all kinds of interesting data including daily temperature and rainfall, periods of hay feeding and/or confinement, applications of chicken manure, bull introduction and frost dates. Organic farmers find these records keep their annual organic inspector happy, and they
are acceptable records for NRCS “prescribed grazing” payments. One farmer is comparing his grazing chart to his milk production records to understand milk per acre. Another farmer charts crops, color-coding the daily entries for planting, spraying, harvesting and manure spreading. When he comes in each fall to update his nutrient management plan,
all the information is at his fingertips.
I would love to hear from farmers who are utilizing some of the newer “apps” such as PastureMap™ or GrazingCalculator ™. Also on the horizon is goGraze™ currently in development as a companion to UVM Extension’s goCrop™ nutrient management software. Ultimately, there are tools available for everyone, whether you want to enter data on the go with your phone or like the comfort of having a tangible paper record.
For the last 5 years, our team has had grant funding from the USDA to do research and demonstration projects investigating novel ways of cover cropping in corn silage and soybean systems in Vermont. We started with a small project in 2013 in Ferrisburgh at Deer Valley Farm comparing 2 different cover crop mixtures planted into the standing corn and drilled after harvest. That project was successful and provided us with enough preliminary data to start investigating additional cover crop mixtures and planting timing on a larger basis.
In 2014, we started our NRCS Conservation Innovation Grant, “Better Cover Crop Mixes in Vermont.” This project enabled us to evaluate several three-way cover crop mixtures alongside a winter rye monoculture. The cover crops were planted into standing corn (at V5/V6 growth stage and at tassel) as well as drilled after harvest. Similarly, we interseeded into soybeans at R3-5 and R6-8. As a result, we ultimately evaluated 15 different three-way cover crop mixtures during 29 different planting events for a total of 319 research plots. This work could not have happened without our farm partners. For this project alone, we collaborated with 10 farms on 13 fields in 7 Vermont towns.
So what? you may wonder. These plots provided us with valuable data to share with producers, NRCS staff, technical service providers and agency folks, and that information is helping us make sound recommendations for successful cover cropping in Vermont. However, the true value of this project (and our other cover crop projects) is the ability to enable hundreds of Vermont farmers to witness, learn about and adopt this practice. In this single grant project described above, we were able to do some amazing outreach to farmers. This included 12 field days, 6 presentations, 7 newsletter articles and 5 Across the Fence television episodes. Our field days involved over 200 farmers, 61 agricultural business employees, and 112 agency staff. Our workshops and conferences reached 153 farmers, 81 ag. business employees and 221 agency staff. And while that in itself is a tremendous feat, the real so what is that we have seen exponential increases in the adoption of cover crops in Vermont over the last 3 to 5 years.
According to the U.S. Department of Agriculture’s Natural Resources Conservation Service (NRCS) data, “Vermont farmers planted a record-setting 25,727 acres of cover crops on more than 2,000 fields in 2016 on approximately 25% of all annual cropland in Vermont. That’s a 58% increase in the acres of protective winter cover crops planted in 2015.” By my count, it is a 250% increase from 2014. While these research and demonstration projects are by no means the sole reason for this impressive rate of adoption, I do believe they are an important piece of the puzzle. Enabling farmers in the Champlain Valley to approach these conservation practices with solid, local information that allows them to be successful. They are able to investigate species, planting methods, potential pitfalls and see for themselves when and if these cover crops make the most sense on their farms, in their soil and weather conditions and with their equipment. And most importantly they are getting the most out of their cover crops by establishing them in a truly effective way, meaning the cover crops are functioning as intended and providing erosion control, taking up manure nutrients, and protecting water quality. In addition, the farmers are figuring out how to do it more profitably, utilizing these cover crops for forage or as a key component in their no-till systems, using less seed and planting it better, and even growing their own seed. Essentially, Vermont farmers are making them an integral part of their farming operations. This is the true meaning of adoption. Not just throwing seed out there because there is cost-share money, but REALLY MAKING IT WORK.
We just finished a two-year, multi-farm study on the health of clay soils, funded through a VT Conservation Innovation Grant through the NRCS. Measures of soil health (using Cornell’s soil health test) were not consistent, and we found that comparing practices over time was more informative than comparing field to field. One interesting, and maybe
obvious, lesson was the correlation between soil health practices and crop yields.
So, how do soil health practices influence yield? Research suggests soil health can improve yields. It is important to note our project focused on demonstration, not replicated research. We compared no-till and conventional/reduced till corn silage on 5 farms with clay fields in our region. A simple t-test revealed no significant difference in yield between no-till (19.1 tons/acre) and conventional (19.2 tons/acre). More importantly, we were able to demonstrate that a farmer can grow no-till without yield losses, and be successful with good management practices. A yield gain might take time as the soil builds up its condition.
We also wondered how cover crop species or mixes might affect corn silage yield. We had an opportunity to use a field where the corn was accidentally killed. We planted 15 different combinations, including 4 single species, 6 two-way mixes, and 5 three-way mixes. This project was a slight anomaly in that the cover crops were planted with a drill in late August, which allowed for a more vigorous production of all cover crops. Radish was a star in the fall, maximizing both phosphorus and nitrogen uptake. We did not measure phosphorus content in the spring, so we do not know how much was retained in the soil. It seems to have allowed
for more available nitrogen in the soil at the time of a pre-sidedress nitrogen test (PSNT), therefore requiring less nitrogen. Surprisingly, legume mix covers had good fall biomass, but that did not translate into more N mineralization.
We applied nitrogen to each plot as per the PSNT recommendation for 20 tons/acre corn silage. At the end of the season, we measured corn silage
yield and compared that to nitrogen applied (see graph). The winter rye plot had a lower corn silage yield and required more nitrogen. Other than the nutrient effect of less uptake and slower decomposition, there may have been a physical barrier created by the standing rye crop, which was particularly vigorous in the spring. However, our three-way mix (winter rye – oats – radish) actually had the highest average corn silage yield, even though it required more N at PSNT time than the pure radish stand.
So, do not go abandoning your winter rye just yet. In fact, we think this three-way mix has promise and we are looking for a mix that gives both fall and spring soil conservation. Radish alone will winter kill, which may be good for mineralization, but not as good for spring soil conservation. Oats also winter kill but provide faster fall soil cover than rye by itself.
When using an over-wintering cover crop, it is clear that timing and success of termination is critical for subsequent crop yields. Nitrogen mineralization may happen later in the season with a plant such as winter rye that has a heavier carbon content. In a no-till system particularly, you may need to adjust your nitrogen rates/timing and put more on upfront. If you are using cover crops, a PSNT seems like a wise investment.
It is also important to remember that soil health is a long game, and it may take time to see the results of your labors with cover crops. We have replicated this project by replanting these cover crops in the fall of 2016, this time planted in September, and will look at this again this coming season.
By Rico Balzano, UVM Extension Agronomy Outreach Professional
Here in Vermont, when farmers are considering a no-till system, several
questions often arise: What about incorporating manure? What about cold
soils? What about ruts leftover from harvest? Vertical tillage offers a solution with minimal soil disturbance and virtually no soil inversion, thereby maintaining a natural soil structure essential for success when otherwise no-tilling.
Vertical tillage can be a vague and confusing term for both equipment dealers and farmers, mostly because there are so many implements that claim to accomplish vertical tillage. A very general definition of vertical tillage equipment is any implement with disks, shanks, or teeth that enter AND leave the soil vertically, only moving soil up and down. Implements that move soil horizontally, such as moldboard plows and disk harrows
(with concave disks), create restriction layers that impede water movement and root growth. These implements shear or smear the soil, which can lead to compaction in or below the tillage depth.
By definition in-line rippers and chisel plows (with straight points) are vertical tillage tools, and can be used to “reset” the soil profile when restriction layer(s) are present. Ideally, this “reset” should happen only when necessary and not on an annual basis, which would just amount to a conventional tillage system. Most often, vertical tillage refers to shallow or surface tillage that sizes and incorporates residue and manure without creating a stratification layer. Usually the depth is limited to 2” to avoid
creating a compacted layer under the seed. This allows vertical tillage to fit into a reduced tillage system, with the goal of seeding at or below tillage depth. Other advantages of vertical tillage in a reduced tillage system include warming the seed bed in the spring, incorporating
cover crop seed in the fall, incorporating manure, and leveling out ruts from harvest or other field activities.
Most vertical tillage tools consist of vertical cutting blades set straight or at a very shallow angle to size and incorporate residue while minimizing horizontal soil movement. Also, most implements have some combination of rolling baskets and cultivator wheels to break up clods and level the seed bed. Aerator machines can be effective vertical tillage tools, especially when equipped with some combination of coulters, rolling cultivators, or rolling baskets. Some manufacturers’ vertical tillage implements have
concave disks or straight disks set on an aggressive angle. These set-ups can help incorporate residue and manure, but increase the chances of smearing soil and creating compaction in the tillage zone. Care must be taken not to use ANY tillage implement when soil moisture is too high, as more harm than good will be done.
Where’s Rico? Rico Balzano has moved to the Rutland Extension office, but he is still an active part of our team and continues to be involved in programming
content and outreach. Contact him at:
(802) 773-3340 ext. 281, firstname.lastname@example.org
Nutrient Management Planning Update Workshop. Tuesday March 7, 10am-2pm, Middlebury Extension Office.This workshop is part of a series for previous attendees of our NMP classes to update their plan for 2017. Additional days by appointment, contact Kirsten (802-388-4969 ext. 347).
Custom Manure Applicator Training. Wednesday March 8, 10am-2pm, Vergennes American Legion this location has changed. This workshop is part of a series of classes for custom manure applicators only. Contact Nate for more information (802-388-4969 ext. 348). Coordinated with the Northwest Crop and Pasture team.
Following the New Required Agricultural Practices (RAPs) in the Floodplain – for farmers. March 16, Conants Riverside Farm, Richmond and April 4, Middlebury Extension Office, 10am-12pm. Both workshops will be discussing floodplain agriculture including: manure spreading ban, incorporation of manure, cover crops on annual cropland, and limitations of stacked manure. For more information contact Nate (802-388-4969 ext. 348).
Manure Training for Farm Applicators. March 21, Woodnotch Farm, Shoreham and March 23, Leach Farmily Farm, Pawlett, 10am-2pm. For custom applicators, farmers and seasonal farm employees. Addressing RAPS – topics include: buffers along surface water and ditches, manure spreading ban dates, soil conditions for manure application, how to read a nutrient management plan (NMP), methods to minimize run-off of manure and its associated nutrients, and record keeping requirements. For more information contact Nate (802-388-4969 ext. 348).
No-Till Planter Clinic. April 6, Gosliga Farm, Addison, 10am-2pm. For more information contact Rico (802-773-3349 ext. 281).
More information or questions about any of these events can be obtained by contacting our office.
802-388-4969 ~ 23 Pond Lane, Suite 300 Middlebury, VT 05753
Events hosted by other affiliates:
Organic Dairy Producers Conference. March 9, 9am-4pm, Vermont Technical College. Hosted by the UVM Ext. North West Crops and Soils Team. More information can be found here.
Annual Grain Growers Conference. March 23, 9am-5pm, The Essex Resort & Spa. Hosted by the UVM Ext. North West Crops and Soils Team. More information can be found here.
Commercial Pesticide Applicator Training. March 30, 8:30am-4:00pm, Middlebury American Legion. For more information contact Ann Hazelrigg (802-656-0493)
Listening Tour: Agency of Agriculture (VAAFM).Ongoing, multiple dates and locations. More information can be found here.
Farm Business and Budget Clinics. UVM Extension. Ongoing, multiple dates and locations. More information can be found here.
Winter Manure Spreading Ban will be lifted April 1, 2017. Even after this date the VT Agency of Agriculture, Food and Markets (VAAFM) prohibits spreading on frozen, saturated or snow covered ground. Questions should be directed to VAAFM.
We all have learned a lot about using no-till and cover crop farming practices on clay soils over the past few years, and feel good about it because improving soil health for the future really is important. If not, I don’t think you would be farming.
But the fabric of agriculture is a bit tricky as one side pulls the covers off the other, then back, and over and over. Field practices to improve crop yields and water infiltration come back to bite us with reports of fear that this will increase the amount of dissolved phosphorus in the soil, which is exactly what you want for better crops, but not if it leaks out and pollutes Lake Champlain. Now the quilt comes off again and it becomes apparent that the environmental damage may be increased by activities like improving soil health with tile drainage, no-till planting, even cover crop roots that go down into the soil to reduce compaction. All are field practices we promote with confidence that this will solve the “problem”.
Now in a recent report from Farm Journal, Field Agronomist Ken Ferrie discusses how improving soil health increases the concerns about nitrate and water-soluble phosphorus losses down through the soil. But let’s not stop with that part of the equation. This is not a bad thing; it’s just that now farmers need to be even more aware of how their field management practices impact their P losses. And how important the work we do at Extension to compare different cropping system components helps farmers decide what balance of tillage and crop types is right for their farm. One response is to stop if we are afraid; the other is to carefully move ahead with calculated confidence that we are making a positive difference, measure the effect, recognize some new problems, and move ahead.
The Required Agriculture Practices are now here, and we will have a lot of “quilt pulling” as changing one thing like – requiring buffers along ditches – may trigger responses that are counter-productive like installing tile in the whole field and burying those ditches. Which way is better? I’m not sure; just that when the quilt gets pulled off me, I pull back. Switching to no-till corn is a proven way to help soil aggregate structure, greatly reduce soil erosion and reduce fossil fuel use. Yet the reaction is that preferential flow paths through the soil form as a conduit to move manure and P too fast through the soil matrix.
The Vermont Tile Drainage Advisory Group report has been submitted to the Agencies of Agriculture and Natural Resources, and will inform the Secretaries for their joint report to the legislature in January. I participated on that advisory group and the discussions highlighted that these issues are not simply good and bad. Every action, like improving soil drainage, forces a conflict between a current farm business and family sustainability, and the cost of water quality remediation for past indiscretions in our lake that we are faced with fixing.
The only way that we will be able to keep a reasonable perspective is for everyone (both sides of the bed) to continue to be vigilant to maintain a good balance of using our land resources to make money, but keep the water clean. This will never end, as the challenges of farming in Vermont are made more difficult with awareness of how a little P makes such a big problem in the Lake.
I heard a great quote: “there are no wrong turns on the journey, just course corrections when we figure out where we want to go next.” I think we should be focused on learning how to make the best next moves, together, for farming practices that will help us meet the P reduction goals of the Vermont Clean Water Act. I don’t agree with the folks who want to curtail the dairy industry in Vermont with hopes that a different farming model or land use is better. Get active in your local farmer watershed group (there are three in Vt.), come to conferences and workshops we offer to get better at these decisions, speak up so the general public and legislative policy makers hear your voice.
USDA has established certain benefits designed to help beginning farmers and ranchers start their operations. These benefits include:
Exemption from paying the administrative fee for catastrophic and additional coverage policies;
Additional 10 percentage points of premium subsidy for additional coverage policies that have premium subsidy;
Use of the production history of farming operations that you were previously involved in the decision making or physical activities; and
An increase in the substitute Yield Adjustment, which allows you to replace a low yield due to an insured cause of loss, from 60 to 80 percent of the applicable transitional yield (T-Yield).
How to Apply for Benefits
You must apply for Beginning Farmer and Rancher benefits by your Federal crop insurance policy’s sales closing date. You are required to identify any previous farming or ranching experience and any exclusionary time periods you were under the age of 18, in post-secondary education, or active duty military. Talk to your crop insurance agent for more information.
Cover Crop Guidelines
Recently the Farm Service Agency (FSA), Natural Resource Conservation Service (NRCS) and Risk Management Agency (RMA) worked together to develop consistent, simple and flexible policy for cover crop practices. Search for “Cover Crops and Soil Health” at www.nrcs.usda.gov or contact your local agency for more information.
Over the past year there has been growing interest in the farming community in trying to no-till alfalfa hay seedings into winter cover crops as a way of reducing erosion and saving time and fuel. Come spring, there will be a number of farmers who want to plant then or early summer who will look at their fields wondering “should I plant now, or wait until later?” While we have not yet done any formal research looking at alfalfa establishment under different management systems and the associated economics, there are some clues that may be able to guide us until we have more data.
One clue we can look at when deciding whether to plant in early spring or early summer is cover crop stand density. (Late-summer seeding is also a consideration that we won’t discuss in this article.) We know from helping farmers no-till-renovate pastures/hay fields that a productive and competitive hay field will outcompete your no-till seedlings for light and nutrients. We should expect this same thing to happen when we have cover crops.
A field was planted to winter rye after corn silage harvest in early September; by December it completely covered the soil surface and was between 4 and 6 inches high.
This success was due in part to early planting, full seeding rate, and timely rain. In spring, we expect that this crop is going to take-off and, with proper management, will be very high yielding. If alfalfa mix were planted into this stand in April without any control methods, will our seedlings be able to compete? Maybe, but we wouldn’t count on it. We are not suggesting that a productive stand is bad, as it provides many environmental and economics benefits, but it must be managed correctly. So, in this situation, we would recommend that before seeding an alfalfa mix, a farmer should either terminate the cover crop, or wait until mid-May and harvest for livestock feed before seeding. If the field is terminated in April, the alfalfa should be planted with a nurse crop like barley or oats. If properly killed, the winter rye will be barely noticeable after about a month. If there is no nurse crop, there will be a substantial amount of bare ground which will be susceptible to erosion and weed pressure.
Another field was planted in late September 2015 to winter rye after corn silage harvest. By early April 2016, although the cover crop did protect against erosion, there was still a lot of bare soil.
A crop like this can produce high quality livestock feed, but will be very low yielding. In this type of situation, the farmer can go ahead and plant alfalfa mix. S/he can terminate the cover crop beforehand, but there should be enough open canopy that the cover crop should not be a problem. This winter rye can later be mowed for livestock feed, or possibly even left and combined for seed for next fall’s cover crop.
Do you have questions about this work or would like assistance with no-till alfalfa? Contact Nate [802-388-4969 ext. 348, email@example.com]
As farmers, nutrient management planners and soil conservationists, many of us deal with the estimated loss of soil from fields. We often use a very important tool called the Revised Universal Soil Loss Equation (commonly referred to as RUSLE2). If you have a nutrient management plan, you know about RUSLE2. This tool, however, only estimates soil loss in the form of sheet and/or rill erosion. This is the gradual and sometimes unnoticeable erosion that sheets off fields or that forms small, uniformly spaced and sized channels (less than 4 inches deep). With proper crop rotations, reduced tillage, good cover cropping, good organic matter and even proper manure applications, we can manage for this erosion fairly simply and inexpensively.
Gullies, on the other hand, are the “unaccounted for” erosion that can have a major impact on soil loss, soil health, water quality, and crop yields. Gullies are water formations with increased intensity to sheet and rill erosion, and can also exacerbate sheet/rill erosion. While we have all seen photos of giant gullies big enough to consume a tractor, those tend to be rare. However, the gullies in Vermont farm fields are no less impactful on our landscape. According to an older, but interesting analysis from USDA-NRCS in 1997, they estimated that (19 years ago), roughly 6.1 tons/acre of soil loss per year was attributed to gully erosion, making up roughly 58% of the total sediment lost through water erosion annually (the remaining 4.5 tons/acre/year was from sheet and rill erosion).
Types of Gullies
Ephemeral gullies recur in the same area each time they form, can be partially or totally erased or filled in with tillage, and frequently form in well-defined depressions or natural drainage in a field. As described by the USDA –NRCS (1997), “most ephemeral gullies occur on fields with highly erodible soils, little or no crop residue cover or where crop harvest disturbs the soil.” They are associated with water flow in areas where runoff is great, including snow-melt runoff like that experienced in the Northeast.
True or ‘classic’ gullies are “channels too deep for normal tillage operations to erase.” (NRCS, 2015). They may get bigger in subsequent years, but can also stabilize and become more permanent drainage channels. They tend to start as ephemeral gullies that were left untreated. They can also start as a result of tillage, for example adjacent to a dead furrow. Or they may start at the edges of established grassed waterways or buffers that were inadequately sized or not maintained.
In this pictured example, a gully started upland as an ephemeral gully, but when it reached a dead furrow, this larger scale channel formed. You can see how quickly a gully like this can be an even more significant contributor of soil loss than typical sheet and rill erosion. Depending on how the field is managed a gully like this can account for two to four times the sheet and rill erosion from an entire 25-acre field. It’s hard to tell, but in the picture you can see the field had been cover cropped and no-till planted to corn, but it was too late to prevent the ultimate result. This gully has subsequently been repaired and now has a diversion at the upland slope to prevent its reoccurrence.
This type of significant erosion has many costs associated with it: water quality degradation, decreased yields, and the sometimes significant costs to repair (potentially tens of thousands of dollars). The cost of fixing and maintaining an area where a classic gully has formed can be drastically more expensive and time intensive than preventing them from forming. Once a gully begins forming, additional measures will need to be implemented. Continuing to till and level out an ephemeral gully every year only introduces more soil into the drainage area for erosion.
Conservation practices to prevent gullies include grassed waterways, cover crops, crop rotation and no-till. These practices relate to not re-tilling the gully area, maintaining residue on the soil surface, keeping soil covered and preventing erosion from starting in the first place.
Grassed Waterways are constructed channels that are planted with fast growing grass species that are mowed regularly to reduce sedimentation. These waterways convey the water to a stable outlet where it will not cause erosion. They not only significantly reduce erosion, but are located in the areas of the field where drainage wants to occur anyway and tend to not be very productive. Once installed, they can be permanent with proper maintenance.
Conservation Crop Rotation is a management practice that simply changes the rotation pattern of the field in question. In dairy forage systems this includes reducing the number of years of corn production, and rotating into a perennial sod.
Cover Crops are close growing crops (grasses, legumes, forbs) planted to provide protection from soil erosion on annually cropped fields in the times between cash crop growth. In addition to other conservation benefits, they provide significant decrease in erosion.
No-Till otherwise known as Residue Management is the limiting or elimination of soil disturbance to maintain plant residues on the soil surface all year. By not tilling, soil is not exposed to erosion and it is more stable and able to infiltrate more water and support equipment operations without disturbance. In conjunction with cover cropping, it may eliminate the need for grassed waterways or other more expensive conservation practices, if the gully erosion has not already become a serious problem.
An existing classic gully will need repair. This is a big ticket item. It often requires significant machine time, may need stone or pipe, and often includes a water diversion structure to prevent it from forming again. These can cost more than $20,000 per gully to repair.
Gully erosion is the not so hidden, but unaccounted for, source of erosion in our watersheds. It is detrimental to our waterways, our cropland and pastures, and the sustainability of our farms. Take an afternoon and take a look around your fields. Do you see any gullies forming? Do you see where gullies could potentially form? See a gully in need of repair? Visit your local NRCS office and get help, either stopping gullies before they start or fixing existing gully problems.
+ Estimations based on field observations and NRCS erosion calculations based on dimensions, frequency and soil type.
While recently attending a Certified Crop Adviser Conference in NY I started doodling Venn diagrams of the information I was digesting. In the world of soil health, the ‘classic’ Venn diagram is Chemical-Biological-Physical properties all interacting and collectively leading to the ever elusive thing we call soil health. Thinking larger, we can ask the question, does soil health always lead to environmental health? Notably for us, does soil health always lead to a reduction in phosphorus loading to water bodies? And from the agricultural perspective, does soil health always lead what I am terming farm health? What I mean is agricultural productivity and sustainability, including economic realities and crop yields. If we add more organic matter, will we always get greater crop yields? If we increase infiltration, will we always get reductions in phosphorus loss? We’d like to think so, but unfortunately for us reality is complex. Along with this Venn diagram is the overlap. Things take time and teasing out these realities to make sound management recommendations can be tricky and confusing. We continue to use a combination of research and demonstration trials in an attempt to approach that perfect union where farms are building their soil quality, increasing their farm profitability and having more positive environmental impacts.
The Possible Use of Gypsum Amendments to Reduce Soluble Phosphorus
Currently on the market are a number of products being sold both for increasing soil health and better utilization of phosphorus. One demonstration project we began this fall in McKenzie Brook watershed is looking at the use of gypsum amendments to increase soil health while also reducing soluble phosphorus loss. Gypsum (calcium sulfate dehydrate) actually has a long standing history as an amendment, as a source of sulfur and calcium (without a pH change). The NRCS has a practice standard for gypsum application to improve physical and chemical properties of the soil, improve water infiltration, reduce dissolved P in surface runoff and subsurface drainage, ameliorate subsoil aluminum toxicity, and reduce potential transport of pathogens in cases of manure and biosolid application. Utilization of this practice is more common in other parts of the US and applied in bioswales. Science research thus far has primarily focused on flue gas gypsum (FGD) and results suggest there is some efficacy in improving soil health and reducing P loss, but the magnitude of effects may vary.
Sulfur is required for protein synthesis and nitrogen fixation, so in theory, additions of gypsum could increase yield potential if sulfur is limiting in the soil. Calcium is also needed in cell wall and membrane function, growth and fruit development. Perhaps even more importantly, calcium can help improve soil structure as a flocculating agent; that is, calcium can help with soil aggregation via its role as a positively charged ion (Ca2+) held by soil’s negatively charged exchange sites (CEC). It has a stronger bond than other lower charge particles like sodium (Na+), which is why gypsum amendments are used in reclaiming sodic and saline soils. This feature is also particularly relevant to our clay soils if soil aggregate stability and infiltration is poor. Gypsum can theoretically reduce phosphorus loss by two related means. The first is by increasing soil aggregation and therefore decreasing the loss of P with sediment. The second is that calcium-phosphorus complexes can form, keeping the P in a less soluble form. We have begun a demonstration project in McKenzie Brook utilizing multiple types of gypsum in contrast to a short paper fiber lime product, and hope to build upon it next year. We will have more on this topic as this project evolves.