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Infiltration Improved by Cover Crops

Infiltration Improved by use of Cover Crops

 


Infiltration is the process of water entering the soil. Infiltration rate is a measure of how fast water enters the soil. Water entering too slowly may lead to ponding on level fields or to erosion from surface runoff on sloping fields. Reducing erosion and runoff also reduce surface runoff of fertilizers and chemicals such as herbicides. Fertilizers and herbicides are agronomic inputs to assist farmers in producing productive and profitable yields. The objective of applying nutrients and herbicides and other chemicals are to benefit the plant. If the inputs runoff, it is a loss to the farmer and the environment.

Plants need water and sunshine to produce crop yield. Infiltration is dependent on soil type, soil organic matter and aggregate stability or soil structure. As farmers utilize conservation practices that increase soil organic matter, soil health indicators such as soil structure, aggregate stability, and infiltration will also improve.

Rainfall simulators have become quite common in Tennessee. NRCS uses them to demonstrate how cover crops, no-till, and good grazing practices improve infiltration and reduces erosion. Below is an example of rainfall simulator at Milan No-till Experiment Station on Soil Health Plots.

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The five trays used were from five treatments left to right, no-till only, NT wheat only, NT cereal rye and crimson clover, NT five-way mix consisting of cereal rye, wheat, crimson clover, daikon radish, and purple top turnip, and NT cereal rye and vetch. Rainfall simulations were run multiple times totaling 3" of water. All trays had good soil structure due to long-term no-till. As you can see by the back jugs showing infiltration, the 5-way mix infiltrated the best.

In another demonstration, the picture below shows minimum tillage (it is still tillage), no-till, over grazed pasture, conventional tillage tobacco with an excellent cover crop, and good grazing. Note that the good cover crop and the good grazed grass infiltrated and had little runoff compared to other treatments which had high runoff and poor infiltration.

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So, all that is demonstration. Let’s put this to the test to real field conditions and real rainfall. Matt Griggs who is featured as the Number 3 in the Profiles of Soil Health Heroes on tnacd.org and also Matt Griggs update Profiles of Heroes. Matt recently sent me pictures in a rainstorm at his farm, true dedication.


Cover crops add more carbon and increases soil biology that increases better aggregates which results in much greater soil structure, pore space, thus better infiltration rates. Pictures below show long-term no-till with standing water, four years plus of cover crops and no-till with great infiltration, and the bottom picture show where the two plots come together. A picture is worth a thousand words. Cover crops with no disturbances from tillage improve soil function, such as here, infiltration.

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Twenty Years of No-till.                                                                                                                      Two years of multi-species cover crops and no-till.

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                                                                                                          No-till alone on the left and No-till with cover on the right.

 Soil health is improved by not disturbing the soil, keeping a root growing, keeping the soil covered, and diversity. The demonstrations and real farm application show continuous no-till with cover crops improve the soil’s ability to infiltrate water. Better water infiltration means better efficiency of water use and more stable yields. Contact your local NRCS office or Soil Conservation District Office for more information on improving soil health.

 

 

 

 

 

 

 

 

A Day in Coffee County

A Day in Coffee County

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Coffee County, Tennessee is one of the top counties in Tennessee and the nation as far as embracing and practicing conservation practices that improve soil health. The reason Tennessee is so successful in soil health is the team approach. It starts at the top, and Tennessee embraced soil health because of Kevin Brown, State Conservationist, NRCS, Tennessee. His top three priorities were and are Soil Health, Soil Health, and Soil Health. TACD and the Board of Directors have embraced soil health and has hired a person to promote soil health, that being yours truly, Mike Hubbs, author. Tennessee NRCS from State office to every person in each field office understand the importance of soil health. Our IMG 2685newcurrent Acting State Conservationist, Jamie Carpenter is following Kevin's lead and promoting soil health. It helps that Jamie's normal job is Assistant State Conservationist for Programs. Having Programs focusing on soil health is huge for promoting and providing financial assistance. Tennessee Department of Agriculture is another major partner that is also supporting soil health in working with District Supervisors and financial support. Again, the team approach has been instrumental to Coffee County's support as well as the entire state of Tennessee.

IMG 2701newCoffee County, like Tennessee, has embraced soil health in 2013. Adam Daugherty, NRCS District Conservationist, Coffee County convinced the Soil Conservation Board that this was the direction they needed to go. Coffee County was already a leader in no-till. They were doing a good job in natural resource conservation. The systems approach of mimicking nature, a deciduous forest was the missing piece. Bringing in cover crops were important, but understanding the function of soils and mimicking a forest was the key. The Soil Conservation Board not only supported the aggressive approach but many of them also jumped in and applied many soil health improving practices.

Coffee County knew that no-till would preserve the benefits of a crop rotation system, but the soil biology was in neutral or status quo. By adding cover crop mixtures with diversity and following good agronomy practices such as planting depth, planting by temperature, preserving moisture when it counts in the summer, covering the entire soil, and balancing the carbon to nitrogen ratio they have unlock some but not all of the secrets of the soil. They and we are always learning something each and every cropping season.

Approximately 70 or more farmers are farming using cover crops, no-till and this system to mimic nature. I think it is incredible for so many to buy into this. Recently I had the privilege to visit and speak to farmers in Alabama. They are beginning to follow some of these principles. On April 25, 2017, I had the privilege to join Adam Daugherty, Allen Willmore, NRCS Soil Conservationist, Coffee County, Steve Musser, Assistant State Conservationist, NRCS Alabama, Jamie Carpenter, Acting State Conservationist, NRCS Tennessee to visit an assortment of farms and see Coffee County's successes in soil health.

IMG 2666newTraditionally, farmers have grown cover crops to around knee-high and waist high, killed the cover approximately two weeks before planting of corn or soybeans and plant in a crispy or dead cover. The weaknesses of this system are it limits the growth in the spring especially in corn. Some farmers in counties as south as Coffee County begin thinking about planting corn in March. As we know, cover crops are fairly short in March and just beginning to kick in another gear in the end of March, especially species such as Austrian winter pea, hairy vetch, and crimson clover. In fact, we dug these plants up on April 25 and found many nodules on the roots of each species of legumes. Nodules when they are pink indicate they are producing nitrogen. To kill legumes early, would be to lose a major benefit from the legumes in the mix. Farmers in Coffee County have learned to wait to plant corn to middle to third week of April. I know there are exceptions, but many farms that we visited had planted only about 7 to 10 days earlier. It was very wet on the April 25th, about 8 inches of rain had fallen a few days prior to our visit. Corn was germinating why we were there with a few acres of corn was still to be planted. Another weakness of planting crispy is once you terminate the cover, there is not an active root growing. This year we are bombarded by rain and cool weather. Having a root growing right up to planting is great way to drain uptake the excess moisture. Once the cover is terminated, the residue will hold the moisture in to the soil. Warm weather will eventually alleviate this problem.

Many of the farmers are planting green. That is plant the cash crop of corn or soybeans (most common crops in Coffee County) in standing growing cover crops. Many will lay down the cover crops at planting with variety of implements. The Coffee County Soil Conservation District has purchased a 30 feet wide I&J Crop Roller. The roller/ crimper does an excellent job crimping and rolling the cover crop down. The advantages of rolling a cover down is to manage the much higher biomass when planting green and waiting later. The cover crop exceeds waist high and much of the time is 60" plus in height with a few times exceeding 72" in height. It is easier to plant in well managed cover laying down in one direction. It is best to plant into or at least generally parallel but also covers are much more forgiving planted in green than after terminated. Coffee County farmers are also using pipes, round drums filled with water, power or utility poles and cultipackers to simply lay the cover down in a manageable fashion. The roller/crimper crimps or damages the plant. So, if the grass is in boot stage or mature and legumes are in early bloom, there will be some termination by rolling and crimping. There will still be a need to apply herbicide to complete IMG 2686newthe termination.

IMG 2696newSince Coffee County has farmers in the fourth season of cover crops, it was great to see the benefits after four years. Some of the observations were on a steep red-clay field that had been in covers for approximately three years. They had been killing the covers early about knee-high to preserve the moisture going into summer. Now after some of accumulation of soil carbon, they were letting the cover grow higher. The field was functioning at a higher-level due to the three years of no-till and cover crops.

In another field near a stream the field was highly productive and was in its fourth year of covers. The farmer had learned through experiences that he needed much more grasses than legumes because of the increased biology. When we pulled back the covers the previous year's residue was decomposing quickly. This is a benefit after three to four years. We normally see water infiltration improvements the first and second year. If we are growing cover crops high enough and managing them by rolling them, we are seeing major weed suppression the second to fourth years in covers. The decomposition of corn and bean stalks in less than a year is seen only after three to four years. Also, while standing on the edge of the field, we noticed the water was clear as a mountain stream. This is impressive right after planting. I made a comment that water looked clear enough to drink. Before I finished the statement, Adam Daugherty swooped down to the stream and took a drink. That is confidence in the farmer's conservation.IMG 2691new

Coffee County also has been in a three-year demonstration following the Haney Test recommendations. Farmers will reduce on some plots down to about 75 units of nitrogen (N) compared to the normal of about 200- 210 units of N. Farmers may be able to cut back on N as we continue to build the soil biology and carbon and nitrogen ratios lower to below 10 to 1 ratio.

IMG 2668newSoil structure in all the fields we looked at are granular at surface with some sub-angular soil structure as we dig deeper into the soil. This is why Coffee County is seeing 6-8" or greater per hour of water infiltration. We have seen by comparing some bare spots or some monoculture-legumes as cover crops that we can lose this soil aggregation quickly and water infiltration will go back to 2-4" per hour. We need diversity and cover continuously to keep soils aggregating. Active carbon that is recently dead residues and cover crops are the key to aggregating soils and for nutrient cycling. Total carbon or soil organic matter is important to keep climbing, but it is much more important to see diverse high-quality carbon being produced annually and being consumed by soil biology providing policing of soil disease, cycling of nutrients, and aggregating soil. If we continue to keep the soil covered, keep an active root growing, reduce disturbances, and maintain diverse covers we will continue to see our soil health or functions improving.

Coffee County is an excellent example to follow. They are having their annual Soil Health Field Day, which is one of the larger field days in the state, on August 3, 2017. To attend, contact the Coffee Soil Conservation District and register and pay. Also, you can follow them of Facebook, coffee Soil Conservation District. It was my pleasure to spend a day in Coffee County.

Roller/Crimper Guidance

Guidance for Using a Roller/Crimper

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Cover crops are significantly important in keeping no-till systems healthy. In any system, cover crops provide valuable benefits to the soil such as reducing erosion, soil compaction, nitrate leaching and weed pressure. Cover crops also increase the amount of organic matter, keep the soil cooler, and provide a source of nitrogen (legumes) while improving soil fertility, water infiltration and water storage capacity. One important component of cover crop management is choosing how to kill the cover crop before the cash crop is planted. This Fact Sheet provides guidance on utilizing a roller/crimper which is one of the methods available to kill the cover crop. Roller technology is used with the taller grass cover crops (cereals) and with the shorter cover crops that have flowered.

Read more: Roller/Crimper Guidance

TACD Visits with Local West Tennessee Farmers

Soil Health Changes in Three Years in Haywood County and Results of Rainfall Simulator at UT Experiment Station, Milan Tennessee

by Mike Hubbs, TACD Soil Health Specialist

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On March 23, 2017, I had the opportunity to visit Bill Parker out on the Solomon Farm in Haywood County. This has been a farm that Bill has farmed the last three years. I had the IMG 2555newopportunity to previously visit the farm in October of 2015. The two previous years of cover consisted of rye and crimson clover. This year was a five-way mix aerial seeded in early October. The stand was decent despite the drought, last Fall. Also, joining me on the visit were two farmers from Haywood County, a farmer from Lauderdale County, a Farmers Cooperative employee working Tipton and Lauderdale Counties, and NRCS employees from Brownsville, Tennessee, Joshua Choate, District Conservationist, and Melissa Rodriguez, Soil Conservationist. First of all, it was amazing the surface changes in the soil noted while  digging. The soil was much fluffier or had better tilth. The structure had changed from a platy structure to much more granular and sub-angular structure. We like to see soil structure with the somewhat rounded shapes similar to marbles in a glass. They form soil-voids or pore space that leads to porosity. Porosity provides space for air and water movement most notably improved infiltration rates. We have noted anecdotal evidences for years with cover crops and no-till. We see it when comparing samples with the rainfall simulator. When compared to long-term no-till and vertical tillage and conventional tillage, samples with two to three years of history of cover crops and no-till perform better under rainfall simulator. They infiltrate better due to more cover and better aggregation due to more active soil biology. There is less run-off and erosion. Water is more efficiently infiltrated and utilized by plant roots. We also observed many earth worms in every shovel full of soil. Bill remarked that he had not seen many earthworms in the past. Earthworms is a macro biology indicator that soil health is improving. Earthworms, like other soil organisms, feed off other soil biology such as bacteria, fungi, nematodes, etc. as well as soil organic material from crop residues and cover crops. Lack of tillage is very favorable to earthworms. As time persists with no-till and cover crops, earthworms and other soil biology will increase. These organisms increase nutrient cycling, aggregation of soil, and movement of nutrients and soil organic matter both upward and downward. Earthworms are nature's tillers. Another indicator that was very observable was the strong earthy smell when digging. The sweet soil aroma was much less in 2015 compared to now. Earthy smell is from geosmin, an organic compound produced from actinomycetes, a colony growing bacteria. As soil is undisturbed and organic matter increases, soil earthy smell increases.

Read more: TACD Visits with Local West Tennessee Farmers

Milan No-till Field Day, July 28, 2016

Rainfall Simulator Results at Milan No-till Field Day, 2016

 

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One thing different about the 2016 Milan No-till Field Day was rain. The field day began early with heavy rain in the Jackson and Milan areas. The Natural Resources Conservation Service (NRCS) and Tennessee Association of Conservation Districts (TACD) had two rainfall simulators with five treatments each. The natural rainfall provided immediate results as we arrived at 7:00 am the morning of the field day. All day long we simulated rainfall with treatments receiving more than 12 inches of rainfall. Farmers and visitors could easily distinguish the differences of the treatments. The rainfall simulators were managed by Greg Brann, NRCS' State Grazing Lands Specialist and Soil Health Specialist, and Mike Hubbs (author), and TACD Soil Health Coordinator/Specialist, Matthew Denton, NRCS' District Conservationist, Trenton, Tennessee, and NRCS' Soil Conservationist, Martha Griffin, Trenton, Tennessee. We had assistance from several NRCS' District Conservationists from West Tennessee.

Read more: Milan No-till Field Day, July 28, 2016