Posts Tagged ‘gypsum’

Cover-crop, cash-crop rotations: saving the environment and your checkbook

Tuesday, May 3rd, 2011

I’ve mentioned before that on my small scale, and given my commute to farm, all the time and machinery and fuel and labor adds a considerable cost per pound to my grain. I’d really like to be able to make it more affordable so more people could enjoy it and I’d get some more economy of scale. So I’ve been looking into the thirty years of research at Rodale Institute on organic cropping systems…specifically no-till. That is a system where you plant your cash crop into an existing mulch or living cover crop. No-till production of corn and soybeans has been well established in that time, but it relied on herbicides to kill the cover crop and any weeds. Rodale has been working on the organic side of that using a roller to kill the cover crop, but their research is oriented to the wetter climate of the Midwest and East. In California it’s not clear how well their system works because there have been some anecdotal failures.

Recently, a video was placed on the ATTRA (Appropriate Technology Transfer to Rural Areas) website showing research done in North Dakota aiming at continuous organic no-till that has me excited. You can watch it if you want, but be warned that it’s an hour long:

A local Soil Conservation District has done extensive work with local ranchers on improving soil health with cover crops there, based on the idea that it was all native prairie at one time which had huge stores of organic matter and perennial plants that sustained it for thousands of years and fed the seemingly limitless herds of buffalo. the farmA prinicipal part of that health would seem to be the microbiological life of the soil, as I mentioned in my previous post on tillage. The soils there are sandy loams without high fertility and they only get about 16 inches of water a year. Plowing up the soil loses a lot of the soil moisture and makes it hard for fungus, bacteria, and nematodes to survive. Since they help extract plant nutrients from the mineral soil it’s vital to support them.

Their research has been based on always having cover on the soil, avoiding tillage (plowing, disking, or otherwise turning over the soil), and using grazing animals to process the cover crops so planting of cash crops can be done. They use as many as fourteen species of plants in the cover crop mix, attempting to replicate the diversity of native prairie. The grazing down of the cover crop avoids driving heavy tractors over the soil and ads food for the microbiological life in the form of manure, hair, and saliva [1]. They did side-by-side trials at their Menokan Farm test site with compost and compost tea on one side and nothing but the cover on the other. The corn in both plots outyielded the county average and, even without compost or tea, had yields within a few bushels of the composted side. The idea is that from here on they will plant a cover crop into the corn stubble after grazing, graze that down, plant a cash crop into the cover crop stubble, and so on. No messing with the soil. Now that’s exciting.

the tractor and the disked cover cropThe Land Institute in Salina, Kansas has been working towards restoring the prairie while producing grain for many years. On their website you can see photos of soil cross sections of native prairie soil and soils that have been tilled since settlement. The native soils are about three feet deeper! The Land Institute has been trying to breed perennial wheat varieties that could be harvested and never disturb the soil, but success there is still decades away. What excites me about the North Dakota trials is that it’s something that can be done now to rebuild soil and, by the way, sequester carbon. Living plants all hold carbon that is released in the atmosphere when they are killed and decay. Soil organic matter holds twice as much carbon as plants and while soil organic matter comprised six to ten percent of untilled soil, today’s typical fields only hold one to three percent. Rodale Institute has done thirty years of research on the subject and concludes that with soil organic matter returned to the levels they achieved in their test fields, the 434 million acres of farmland in the U.S. would sequester carbon dioxide to the equivalent of taking one car off the road for every two acres. That’s only their research but it holds great promise.

Admittedly, North Dakota has a different climate and soil than California Central Valley and foothills. For one thing, we have soils very deficient in calcium, as I explained in the last post. But they are worse off for organic matter so the comparisons are not entirely inappropriate. One concern for the long-term future that I have when looking at my soils and most agricultural land is that our supplies of mined gypsum and lime are finite just as petroleum is. I need to add a lot of both of those two but somehow I have to avoid doing it forever. I think that’s where the microbiology will come in.

the combine at work in the fieldI am planning to do some of my own trials to see if I can use continuous cover crop/cash crop rotations. There is a cattle farmer who is renting land where I’m farming and he has divided my thirty acres into three plots. I’m hoping to put in a multi-species cover crop on the grain stubble in the fall of this year and have him put his cattle on it in late winter, taking soil tests before and after the grazing to see what happens. I will be plowing down my legume cover crop on the plot where I’ll plant grain this coming fall so that I can get some serious increase in organic matter. The soil tests on the grazed plot will guide what I do in coming years. If I can get good increase in organic matter and balance the minerals with surface applications of lime and gypsum, I hope that one day I can put away the disc and just plant into stubble. That would not only save lots of carbon dioxide emissions but would save me a lot of money in fuel, tractor repairs, commuting, and sitting on the tractor. My grain would become much more affordable as a result. That’s my project for the next few years. I’ll keep you posted on the results.

[1] The tests aren’t entirely organic because some of the fields started out with heavy weed pressure so they wanted to give the cover crop a running start with herbicides to suppress the weeds. After the one application of herbicide, though, they just grew a cover, grazed it down, and planted corn right into the stubble.

Sustainable (and affordable) Fertilization on an Organic Farm

Monday, November 29th, 2010

One of the puzzles I have been pondering the last three years of my grain operation is how to affordably and sustainably fertilize and manage an organic crop.

Non-organic seed and fertilizer are cheaper, you can use chemicals to control weeds and pests, and the record-keeping is simpler. I am convinced, though, that petroleum based fertilizers are unsustainable for society and that endless use of chemicals is destroying the soil and the environment.

My first year of farming grain I didn’t have time to do anything but buy fertilizer so I bought the amount the rep suggested. I got a pretty good crop but the cost was astronomical and certainly not feasible for the selling price of the finished grain. I tried to grow a berseem clover cover crop but it failed miserably because there wasn’t any rain for quite some time after I seeded and then it was cold so the clover didn’t grow.

a mustard cover cropLegume cover crops create nitrogen, contribute biomass, suppress weeds, hold moisture in the soil, and help balance other minerals and trace elements in the soil. My second year I was leery of spending money on a cover crop that might fail but it was clear that I just couldn’t spend so much on fertilizer. I set a limit of $1000 for my 8 acres, and that turned out to be not enough. The result was a mediocre yield and really low protein levels in the wheat. I just didn’t have enough nitrogen and had too much of other things like manganese. Nitrogen has a major effect on protein and protein is necessary for good rising in bread. Last fall I put in a cover crop on the fallow (unused for a cash crop) ground and got a stupendous crop because of rain through the spring. I plowed that down in the spring and am planting into that this fall so I have the benefit of the nitrogen it created for my grain crop.

This fall I got that same soil tested and found that pretty much everything except manganese was still very low. Excessive manganese inhibits plant uptake of calcium and therefore limits the grain plant’s ability to use nitrogen available. To solve this I need to put in as much as 4 tons of compost per acre (as it offsets manganese) plus lime and gypsum on top of the cover crop. I can’t really afford to do all that in one year and have a reasonable sale price on the grain, so this fertility building is a 3- to 4-year project.

reed on the tractor getting ready to plantAnother aspect of the whole puzzle is the cost of tillage (turning the soil with farm implements and tractor) in labor and fuel, compaction of the soil from that tillage, calcium depletion from tillage, and suppressing weed growth. The simple way to suppress weeds is timely is using a disc or field cultivator but it’s not good for the soil because it destroys microorganisms and depletes calcium, compacts the soil making it less water absorbing and harder for plants to extend their roots, and it costs money. There has been a lot of interest and experimentation with planting into cover crops that have been rolled with a heavy implement mounted on a tractor. This avoids the excess tillage, suppresses weeds with the mulch of cover crop, and gets fertility from the legumes.

It seems to work well in the east where the Rodale Institute has been experimenting with it for some years. One of my problems is that I need to get a lot of organic matter from decayed plants into the soil to allow the microorganisms to grow and increase the carbon-to-nitrogen ration for plant growth, so I can’t skip the tillage right now. If I get the soil built up, theoretically I could grow a perennial legume cover crop that I could plant into with a planter that can penetrate the cover (no-till drill).

Another problem we seem to have in dryer climates is that the mulch makes great rodent habitat. I know of growers who have tried it and had major problems with them eating the cash crop. In Australia farmers often use what’s called a ley system where they plant a perennial legume cover crop that reseeds itself. Every other year or two they till in the cover crop and plant grains. In the intervening years they graze animals on the cover crop that has come back up. In California the problem is that those type of cover crops succeed as perennials because they are good at taking up water – water the grain plants need too. I’d like to try that but I’m wary of putting much land into an experiment without some more research.

green wheat plants with heads just filling outIn the long run, agriculture must manage with less petroleum input. With vegetables that’s more feasible than with grain, where much of the work is mechanized. I keep looking for the magic formula that would avoid the damage and cost of tillage while still building the soil, suppressing weeds, and keeping my costs as low as possible. In addition to the direct benefits of such a program, cover cropped fields are very effective carbon sinks, something we need desperately as we deal with climate change. At the moment I don’t have the answer and I can only experiment so much without risking a major mistake. I gotta have something to sell.

As of this date I have found I can get the compost mix I need but can’t get a spreader to put it on. I’m scrambling to find blood meal fertilizer (high nitrogen) and half the lime and gypsum really needed so I can get it on and plant before more rain. Using half the lime and gypsum is just so I can keep my cost of production down. If it increases yield from 1200 to 1800 lbs. per acre the fertilizer alone will still cost $.20 per pound, not to mention fuel and labor to put it on and the same for planting the grain. Besides that I’ve got the labor, fuel, and seed that went into planting the cover crop. All this has to be figured into my selling price and that’s why small scale organic grain is expensive. If I were using the same machinery on 30 acres and buying three times as much lime, gypsum, and compost or fertilizer the cost of the inputs would be lower and the machinery cost spread over more pounds of grain.

It looks like I may not get a cover crop in this year because of the rain, so next fall I will have to compensate with more blood meal and plant a cover crop on the field for the 2012 grain. Both the 2011 and 2012 crops will get lime and gypsum as the soil tests indicate with hopes that by 2013 I will have to spend far less money on them and my grain production will have increased substantially.

As with every farm, mine is an exciting gamble and experiment. I don’t claim to have any answers but I hope this post has informed and inspired you. I’d love to hear from other farmers about how they’re tackling these challenges.

-Reed Hamilton