Episode 8 - Cover Crops: Improving Biodiversity and How that Benefits Cotton 

Arkansas Row Crops Radio, providing up to date information and timely recommendations on row crop production in Arkansas.

Bill Robertson: Welcome to Arkansas Row Crops Radio, my name is Bill Robertson, Cotton Extension Agronomist, for the University of Arkansas System Division of Agriculture. Joining me today will be Gwendolyn Ellen, who facilitates the functional Ag biodiversity working group at Oregon State and she also does biodiversity consulting. While Gwen is currently at Oregon, she is from Tennessee and does know cotton. 

Special thanks go to BCI, better cotton initiative, for sponsoring this podcast that is the first in a series to highlight the benefit of improving soil health. This is in an effort toward documenting continuous improvement on the farm to ultimately improve profitability of growers as well as providing a source of verified sustainably produced fiber that the cotton supply chain desires. 

To start with, I wanna discuss four ideas defined by USDA-NRCS to ensure healthy soil. The first is to keep the soil covered as much as possible. Two, keep plants growing throughout the year to feed the soil. Three, enhance diversity as much as possible using crop rotation and cover crops. And fourth, disturb the soil as little as possible. 

The focus of this podcast is to highlight diversity and discuss how we can enhance diversity in the cotton production and what this diversity does to help us. Gwen were glad to have you here with us today.

Gwendolyn Ellen: Thank you, Bill, for the introduction and for setting the stage for this Podcast, Biodiversity working for Cotton Farmers. Today's farmers are interested in increasing biodiversity on their farms for the multiple benefits it brings to their farming system. One of the most well-known benefits is the increase in populations of beneficial insects. But, did you know there are other equally vital benefits on increase on-farm biodiversity? Environmental resiliency through erosion and weed management, as well as increased soil and watershed health, are proven worldwide benefits of on-farm biodiversity. When farmers adopt practices that increase biodiversity they can increase their farms economic resiliency as well. The practices reduce production cost by decreasing needs for pesticides and fertilizers. They can raise and stabilize yields and at the same time enable cost-effective compliance with environmental regulations and farm bill conservation programs. This also gives farmers access to markets that require biodiversity-friendly production, such as the currently growing market for sustainable cotton. Now, that really is agricultural biodiversity working for all of us. 

So, how do cotton farmers increase biodiversity on their farm? The first, and simplest step is to recognize the biodiversity that may already exist on the farm, then conserve it and enhance its benefits. So, if we were in the field, I would have us walk out to the edge of the cotton and all do a 360-degree turn describing what we see. Most farmers would definitely see their crops and the weeds. But what is adjacent to the field? Permanent sod grass, a creek, maybe even a forest? Are they remnant ecosystems? Most likely. If so, they may contain flowering native species that require little management on the farmers part and are already providing valuable resources for beneficial organisms such as beneficial insects and predator birds. Keeping these areas free of invasive weed species or alternate hosts for your crop pests and diseases, allowing them to flower, and even enhancing them with strategic plantings are some steps that can be done to increase the farms biodiversity without using valuable crop production space. Today, severe pest outbreaks in cotton rarely occur unless there have been major disruptions in the balance of beneficial insect populations. The truth is, these beneficial insect predators and parasites of cotton pests have been keeping cotton production successful since the first cotton field was planted. Though they are not fast-acting, they are naturally occurring and when allowed to thrive they decrease the likelihood that pest populations will exceed economic thresholds in the field or eliminate cotton producers profits. The conservation of beneficial insect populations is the goal of every cotton farmer that wants to produce a sustainable cotton product. So, just who are these beneficial insects we want to conserve in cotton fields? 

In 1999, extension personnel across the cotton belt came up with a list of the top 10 generalist predators of cotton pests. High on the list were the true bonds, they often have bug rod in their common name. They occur on the cotton plant and they eat live prey all of their lives. They include the minuet pirate bugs, big-eyed bugs, damsel bugs, and assassin bugs. Then there are other more common predators on the list; the lady beetles, spiders, fire ants, and ground beetles. Hoverflies and green lacewing are also on the list. They are unique in that they spend time off the farm in adjacent ecosystems, and, as adults, they need food in the form of pollen and nectar. The top parasites were mostly parasitic wasps, these guys, like the predators just mentioned, pray upon many cotton pests that include a fenced moth eggs, caterpillars, budworms, armyworms, and cutworms, stink bugs, corn earworms, whiteflies, and cabbage looper eggs. Practices that conserve these beneficial populations provide shelter, food, and flowers, and insect pray. The practices are often called insectary planting, and they come in many configurations such as strips and blocks and in plantings in the field. They can even be crops themselves, and they can be planted in adjacent areas as I discussed earlier. Providing these insectary habitats doesn't always require big changes to the farm, in fact, you may already be using practices that provide resources for beneficial insects such as crop rotation, cover cropping, and conservation strip tillage. And there is even more good news, implementing these practices also increases overall farm biodiversity and that comes with the whole additional array of benefits I discussed earlier. 

Let's talk about some of the practices you might already be using, and their benefits just briefly. First is crop rotations. Farmers have known for years that growing crops in rotations instead of mono-cropping cotton year after year breaks up the crop pest life cycles. In studies as early as 1988 farmers in Alabama discovered that they could also reduce their nitrogen fertilizer use, and, at the same time boost their cotton lint yield by using 2- and 3-year rotations of cotton with rye, corn, and vetch. Farmers have been using such rotations in cotton ever since. Another practice is cover cropping. Cover crops are the superheroes of agricultural biodiversity, that's because they perform multiple beneficial functions on the farm. In fact, they are included in those four ideas for healthy soil Bill described in his introduction. They keep the soil covered, they keep plants growing throughout the year, they diversify the cropping system, they help lessen soil disturbance. This soil cover also provides erosion protection, weed management, and excellent beneficial insect habitat. Cover crops are also good at increasing soil nitrogen, soil organic matter levels, and the soil water holding capacity. And as if that wasn't enough, they can prevent nitrate leaching into groundwater, sequester soil carbon, provide a cash c crop, as well as increase yield. Consider extending your winter annual cover crops to fill wedges by dry pivot corners and waterways, and not mowing or tilling them in until the end of the season. They will increase refuge for beneficial insects and provide weed management at the same time. Adding an annual flowering broadly, such as phacelia or buckwheat to your summer cover crop, and allowing strips of it to flower will supply floral resources allowing beneficial resources to flourish early in the season when they are needed. Farmers in other areas incorporate flowering winter covers into their cotton production. These are sometimes mixed with the grass covers such as cereal rye. Species they use include forage sorghum, clovers, vetch, and field peas. A good example of this are a group of Georgia farmers that have been combining strip tillage with cover cropping for four decades. In the early studies, ground-dwelling predators were increased 14-fold. Larger fire ant populations and strip filled fields resulted in increased predation of Heliothis eggs and a net return of 60 dollars an acre in higher profits. While, those are some of the practices you might already be using, but there are other ingredients for diverse cotton farms which have a steeper learning curve. They involve establishing native plant species appropriate to the specific ecosystems they came from; such as forest meadows and riparian areas. Good examples are a hedgerow along the fence row or road, plantings along waterways, or a beetle bank. Beetle banks are permanent strips of native grasses that provide refuge for ground predators such as beetles and spiders. Why use native plants? Well, they perform well in their native soils because that's where they grew up. They are known to be resilient to climatic extremes such as drought and floods. They are more attracted to native pollinators and beneficial insects than to crop pests, and they can displace invasive weed species for decades. These perennial habitats, though more complex to establish, provide all of the ecological benefits we've been discussing, but, for longer periods of time. And their benefits increase over time as their floral resources increase. They also provide vital habitat quarters for beneficial organisms that move through the farm, helping to provide an ecological balance. Ecological balance, resiliency, diversity, soil health, these are all outcomes of the conservation practices presented in this podcast and they are key to sustainable cotton production. I hope you will consider putting biodiversity to work on your cotton farm today. 

Bill Robertson: Gwen, we appreciate you sharing your expertise on biodiversity with us today. And thank BCI for their sponsorship. This has been Bill Robertson and I want to remind you to support Arkansas Agriculture by eating rice and wearing cotton. Thanks for joining us on Arkansas Row Crops Radio. 

Arkansas Row Crops Radio is a production of the University of Arkansas System Division of Agriculture. For more information please contact your local county extension agent or visit uaex.edu