Welcome back. So in the last session we talked about the problems of soil degregation. Specifically compaction, salinization and erosion. In this section we'll talk about what farmers can do and what policy makers have done to address the problem of soil erosion. Specifically, will talk about four examples of interventions on a farm and one example of a policy intervention. On-farm intervention number one is adding organic matter to soil. We have the importance of soil organic matter not only for the ecosystem services it provides, but also in helping to slow runoff, and reduce the potential for erosion. Farmers can incorporate organic matter into their soil via the addition of compost, which is decomposed organic matter, as shown here in this photo. And compost is often made from animal manure, food wastes, crop residues, coffee grinds and other organic materials. On farm intervention number two is planting cover crops. Cover crops such as clover, vetch, oats or winter rye are crops, usually planted over the cool season, and their primary function is to blanket the land, protecting the soil from erosion, in some cases suppressing weeds. Cover crops can also be plowed under, incorporating more organic matter back into the soil. Leguminous cover crops, such as clover and vetch, have the added benefit of adding nitrogen, an important crop nutrient, into the soil. And here's how that works. The roots of leguminous crops are colonized by symbiotic bacteria. And those bacteria capture nitrogen from the atmosphere a process called nitrogen fixing thus making that nitrogen available for crops to use. Certain other cover crops such as mustard, shown here, that’s those yellow flowers, have the added benefit of producing compounds that suppress weeds and other soil borne pests. Third on farm intervention and this one is called conservation tillage. Conservation tillage is an approach to soil cultivation in which crop residues are left behind. Think of the stalks of corn that are left over after the ears have been harvested. Those stalks, those residues can act as a mulch that protects soil from erosion. So specifically, some conservation tillage methods include something called no till. That's where, as you expect, the soil is not tilled at all, as the name suggests. And in no till systems, the previous year's crop is often flattened with a machine called a roller crimper. Something like what you see in here, and again what you wind up with is a blanket or a mat of the previous season crop, which prevents erosion and suppresses weed growth. Then when you’re ready to plant for the next season harvest, you use something called the seed drill, which injects seeds through that blanket into the ground beneath a mat of mulch. Another form of conservation tillage is called strip tilling, shown here, in which narrow strips of land are tilled but the rest is left undisturbed. The fourth, on a farm, intervention, to address soil erosion is a little more revolutionary than the rest. And that is to grow perennial crops. That remain year after year. Growing perennials means that you don't have to till after every season because you're not planting anything new. Wes Jackson is a botanist, crop geneticist, and founder of a place called the Land Institute in Salina, Kansas. And Wes Jackson's work is on the development of perennial grains. His idea is to mimic the perennial grasses of that region, of the midwest. Thus looking to nature as a model. The benefit or one of the many benefits of this approach is that native perennial grasses have deep roots systems that hold soil in place. So compare the root system on the bottom, that of the perennial wheatgrass to that of annual wheat. When you see those side by side you really get a good sense of why the dust bowl happened in the first place, in the 1930s. Farmers plowed up those perennial grasses, and replaced them with annual grains. And those shallow roots do very little to hold soil in place, thus making it more susceptible to erosion. Finally, let's talk about at policy intervention aimed at conserving soil. The US Farm Bill is arguably the most influential piece of federal legislation in terms of what we eat and how food is grown. The Farm Bill is renewed every five years or so In it shapes, federal involvement and numerous functions including providing nutrition assistance tool in low income families, ensuring farmers crop loss and incentivizing farmers to conserve soil and conserve wet land. Here's a quick quiz, it's called ten gentle but i think it's fun. Which programs do you think comprise the largest portion of the Farm Bill budget? Ready, all right, and here's the answer. It's that large blue section, nutrition programs such as the Supplemental Nutrition Assistance Program, formerly known as the Food Stamp Program, comprise the largest share of the Farm Bill budget. So even though it's called the Farm Bill, I just point this out because it's not just about farming. It effects many different aspects of our food system from farm to fork. So okay, let's get back to soil. So the 2014 version of the Farm Bill saw several key changes. Including an $8 billion cut from the supplement nutrition assistance program, an increase in the amount of research funding for sustainable and organic agriculture, the removal of direct subsidies for farmers growing commodity crops, increased funding for federally subsidized crop insurance and that is insurance against crop loses, for example as a result of pest outbreak or unfavourable weather, and finally, now, here is the key change that provides powerful incentives for farmers to conserve soil, and that's called conservation compliance. Now here's how conservation compliance works in a nutshell. In order to be eligible for federally subsidized crop insurance, farmers must comply with certain conservation measures that require them to take steps to conserve soil and wetlands. This is actually a requirement that my colleagues and I, at the Center for Livable Future, fought hard to promote among policy makers. And in the end, it was approved. Conservation compliance, as it was instated in the 2014 Farm Bill, has two provisions, sodbuster and swampbuster. Great names. So the sod of sodbuster refers to a layer of soil held together by roots. That's what sod is. Sodbuster is an antiquated slang term for a farmer, literally one who busts sod or breaks sod. As in plowing prairie grasslands is your busting sod. But the irony here is that conservation compliance, it's not really about busting up sod, it's more about, conserving soil, so the name's a little misleading. But in any case, the sodbuster provision states, if farmers are to cultivate land with a high potential for erosion, they must use conservation tillage, among other measures, to minimize a potential for erosion. Sodbuster also disincentivizes farmers from converting virgin prairie and other sensitive ecosystems into cropland. The second provision in conservation compliances called swampbuster, this one disincentivizes farmers from draining wetlands for crop production. Many may view wetlands as for the birds or only for people who care about birds. But in fact wetlands provide numerous important ecosystem services including buffering storms, mitigating flooding, filtering contaminants from water, and storing carbon that would otherwise contribute to climate change. Now, you may be wondering why would farmers even want to convert a wetlands to a farm, and the reason being that wet lands are a golf mine of fertile organic matter. So in exchange for federally subsidized crop insurance, which is essentially a safety net funded by tax payers, farmers are now required to comply with sodbuster and swampbuster. These conservation measures can go a long way in promoting long-term agricultural sustainability, improving water quality, sequestering carbon, and protecting the public's health. So let's review what we've covered so far in this lesson. We talked about industrial crop production And some of the health and ecological challenges associated with it. I introduced the concept of agroecology, a holistic alternative to industrial production that looks to nature as a model. And a common thread in agroecology is the importance of building what farmers call healthy soil. We explored what soil is made of and how soil organic matter can provide essential ecosystem services. We talked about agricultural practices that degrade soil via compaction, silanization and erosion. And finally we discussed five interventions aimed at conserving soil, so hopefully by now I've convinced you that fertile soil is a foundational natural resource essential, not only to food production, but also to public health and long term food security for future generations. Thanks for listening. It's been a pleasure. And we'll see you next time. [MUSIC]
