What Is Agricultural Biodiversity And Why Is It Necessary For Healthy Soil?
Biodiversity on your farm means having a variety of plants, animals, and microorganisms – both above and below the soil. The more biodiversity you have, the more stable your farm and the more resilient it will be to dramatic swings in weather patterns.
It takes a diverse mix of plants to create the soil biodiversity that feeds your crop roots. A diversity of plants also brings pollinators and beneficial insects to your farm, doing the job pesticides have done in the past.
Tillage, pesticides, and bare earth decrease your agricultural biodiversity and increase your reliance on inputs to produce a good yield. Conventional practices, over time, destroy your soil structure, kill microorganisms, and monocropping saps your soil of nutrients.
Agricultural Diversity is an Economic and Soil Win-Win
Your crops are not only the source of money for your farm, they are also the go-between for soil health and the atmosphere. During different life stages your plants encourage different insects and soil microorganisms. Having biodiversity on your farm is not only good for the ecosystem, it’s good for your pocketbook. According to the Tennessee Extension Service,
“Increasing farm diversity offers the opportunity to increase profits while decreasing production costs. Adding new crops that fit the climate, geography, and management requirements can increase profits by providing the opportunity to exploit niche markets, expand marketing opportunities, and offset commodity price swings.” (1)Do you want to hedge your market bets, or gamble on one crop? Agricultural biodiversity makes economic sense. So why are you or your neighbors still monocropping? Is it because it’s always been done that way, or that’s how we all farm around here? Even if you don’t believe in Climate Change aren’t there good reasons to “be the leader” and change to a biodiverse farming system?
How You Can Convert Conventional Farmland To Agriculturally Biodiverse Acres
The first step is to observe and test. Walk around and in your fields. Are there areas that are under performing, even with inputs? You know the areas. They never give you the return you expect, no matter how many inputs you throw at them. With drone technology, these days you can contract a drone pilot and they’ll take photos of your fields. That’s helpful in the spring when it might be difficult, because of wet areas, to see all that’s happening. And when you’re farming hundreds of acres it’s hard to walk them all.
Look at areas that are underperforming, are they wet, dry, can’t tell what the matter is? Questionable areas need to be walked, but at least you know where to look. By the way, take a shovel with you to see what’s underground. And get soil tests of the underperforming area and a high-performing area – compare them to determine what actions to take.
Look at areas that are susceptible to compaction, wind or water erosion, or pooling and incorporate native plantings. You can reduce expenses by not attempting to make that low spot productive, for example, and use that money on highly productive areas of your fields. Using native plantings has numerous benefits including attracting beneficial insects, increased microbial diversity, and an increase of money in your pocket. Because most native plant species are either perennial or self -seeding you only have to sow that area once.
The Value Of Pioneer Plants In Establishing Agricultural Biodiversity
Many people refer to pioneer plants as weeds. But they serve a valuable function in creating biodiversity on your farm. They’re tough. You’ve always considered that a bad thing, but when converting a conventional farm to a biodiverse one they may be the only plants that can survive in what has become dirt (dead, inert matter).
Pioneer plants are established in a field in many different ways. Animals such as woodchucks, skunks, and raccoons take a shortcut through your field and deposit scat. There are always seeds of some kind in that scat and they are covered with microorganisms. Birds fly over your field and their droppings contain seeds with a coating of microbes. Those are the beginnings of life in a field that’s dead dirt.
Those seeds sprout and have a nutrient source already available to them. As their roots go deeper into your dirt microbes are carried along, beginning to change your dirt into soil. Of course, many seeds land on your field from pioneer plants that have windblown seeds. These are the toughest of all, and some of the most beneficial.
Many pioneer plants are extremely deep-rooted (hence the difficulty in ridding your field of them). Those deep roots in plants such as the windblown dandelions, are mining nutrients from the subsoil, bringing them into the topsoil for shallow rooted plants and microorganisms to use. They prepare your field for cover crops and cash crops that aren’t nutrient intensive.
Wouldn’t it be better field management to mow them down rather than try to kill the root? After all, the root has large quantities of nutrients microorganisms will transfer to shallow-rooted plants as the root decays.
Pioneer plants are only necessary on highly degraded farmland. Instead of letting your soil lay uncovered all winter plant a cover crop so the soil microorganisms have something to eat and you don’t lose soil to wind and water erosion.
As you observe your farmland mark the perpetually underperforming areas. Are you going to waste seed there again this year? Those areas are prime candidates for “prairie strips” or areas to incorporate native wild plant species.
The Benefits Of Areas Of Native Flowering Species For Agricultural Biodiversity
Greater biodiversity creates habitat for beneficial insects and a more diverse soil microbial community. In an underperforming area you have nothing to lose by converting it to native species, and everything to gain. If you decide to dedicate strips down your fields to native plantings you will reap even more benefits. A study by Lisa Schulte, et al found:
“Results from a multi-year, catchment-scale experiment comparing corn and soybean fields with and without prairie vegetation indicated prairie strips raised pollinator and bird abundance, decreased water runoff, and increased soil and nutrient retention.” (2)
The benefits of the prairie strips far outweighed the acreage used and had minimal impact on crop yield for the entire field. Replacing 10% of monoculture cropland with an agriculturally diverse strip of native plants resulted in 20 times more soil retention and 4.3 times more phosphorus, according to Schulte, et al. The key to a healthy prairie strip and crop yield lies in not using synthetic chemicals.
Pollinators and beneficial insects that live in those strips, as well as the plants themselves, are susceptible to herbicide and pesticide drift. Beneficial insects pollinating crops sprayed with insecticides will die along with the pests.
Agricultural Diversity Limits The Pest Zone
When a field is a mono-crop it’s very easy for specialized insects to find – and remain – in a field until it’s devoured. In your large mono-crop field you’ll spray insecticides, either proactively or before the totally devoured stage of insect damage is hit, but there will still be a loss of productivity. Planting a diversity of crops in a relatively close area creates a rich population of above and below-ground beneficial organisms that control insect pests naturally.
When a plant is attacked by a pest it sends out a chemical signal, or volatile organic compound, to surrounding plants while it engages its own defense mechanisms. In a mono-crop it’s difficult for plants to survive a large onslaught of pests. There are two reasons for this; insects will come in much larger numbers because they also have communication systems that let the whole swarm know there’s a meal ahead and monoculture crops, in dead dirt, are dependent on you for all their nutrients.
A mono-crop isn’t as healthy as a biodiverse crop and has less energy to expend on defense. Crops grown in an agriculturally biodiverse no-till field have beneficial soil microbes and on the plant biomass that gives broad-spectrum resistance to insects. In a field with areas of native plants beneficial insects are waiting in the wings, so to speak, for their next meal. For example, praying mantids, spiders, ground beetles, and rodents all feast on grasshoppers – but only if they can get to them.
Agricultural Diversity Can Increase Field Productivity
With diversity in plants, especially field strips of native plants, comes a diversity of pollinators. This is always beneficial to field crops, even if they have been bred to be self-fertile. According to Lisa Schulte Moore, of Iowa State University
“…wild bees and honey bees can improve soybean yields upward of 20% when they help pollinate the soybean plants…compared to improvements in crop genetic and management factors, which ranged between 8% and 15%.” (3)
Soybeans are just an example of the higher production you can achieve when you incorporate pollinator-attracting native plants on your farm. A great deal of research around the world has shown that agricultural diversity has wide-ranging economic effects. Claire Kremen, at the University of British Columbia says “…small habitat patches can improve production and profits for a whole array of crops, by improving crop pollination and pest control and reducing pesticide use.” (4)
Agricultural Biodiversity Isn’t A New Idea
The traditional indigenous garden of corn, beans, and squash is an example of interplanting crops. These three crops help each other. A study by Zhang Chaochun, et al found that corn, beans, and squash grown together had a higher yield than each grown in monocultures. There is a below-ground root complementarity that results in the higher yields.
They found the three crops forage for nutrients in different ways. Corn has shallow roots, bean roots go deeper and are much bushier, and squash roots are dependent on the availability of phosphorus. Zhang concluded that “…species differences in root foraging strategies increase total soil exploration.” And this use of all soil nutrients available results in higher yields.(5)
What other crops have rooting systems that complement each other? Many grasses are deep rooted while clovers are shallow. Corn is a grass. This is a biodiversity question that has to be worked out by each farmer based on soil structure and farming goals.
There Are Many Aspects To Agricultural Biodiversity
“Bio” includes all the biological players on your farm, including you. Plants, animals, insects, microorganisms, the list goes on… Each has a role, or roles, to play on a biodiverse farm. Creating the greatest amount of diversity is one of your roles.
Sometimes leaving a part of your farm untouched is the best management practice. A woods doesn’t need much management and it maintains a healthy biodiversity of plants, animals, and organisms (seen and unseen). Unless you heat with wood that fallen log will serve many tenants over its period of decay; from woodchucks who make a burrow under it, to fungi that may fruit as mushrooms.
An agriculturally diverse farming operation is economically and biologically fulfilling. With diversity comes the knowledge that you’re not dependent on any one crop or the fluctuations of the market. You can take your farm in whatever direction you choose and know that if you keep it biologically diverse you win in $ profit and soil health.
Agricultural biodiversity is important in today’s world. As a farmer you know the difficulties each day brings, and the uncertainties. Having a second or even third crop can bring you peace of mind in a rapidly changing world. A biodiversity strategy is both an economic and a soil fertility necessity.
I hope this was informative. Please share with your neighbor farmers and be sure to check our blogs on sustainable agriculture.
Sources
https://extension.tennessee.edu/publications/Documents/W235-D.pdf
https://www.pnas.org/content/114/42/11247
https://www.agrinews-pubs.com/news/science/2021/07/26/pollinating-insects-can-help-soybean-yields/
https://www.agrinews-pubs.com/news/science/2021/07/26/pollinating-insects-can-help-soybean-yields/
https://agris.fao.org/agris-search/search.do?recordID=US201500057864 Root foraging elicits niche complementarity-dependent yield advantage in the ancient ‘three sisters’ (maize/bean/squash) polyculture [2014] Zhang, Chaochun; Postma, Johannes A.; York, Larry M.; Lynch, Jonathan P.;
