to Cotton Production
By Bill Robertson
Since the introduction of pesticides and commercial fertilizers in cotton, growers have shifted our production philosophy toward increasing yield through the increased use of inputs. This philosophy is based primarily on optimizing yield, hoping to produce enough lint to cover expenses and have a little money left over for management and overhead.
For many years, we were successful in spending extra money and getting an acceptable return on our investment. This has led to practices that address symptoms as opposed to correcting problems.
Bill Robertson
A prime example is nutrient deficiencies. We spend extra money on fertilizer to address the symptoms instead of fixing the problems that restrict rooting — which limits the ability of the plant to extract the nutrients it needs even when soil tests indicate they are at sufficient levels. In today’s economic environment, the luxury of having extra money in the budget to address symptoms is becoming limited.
An alternative philosophy is to use fewer inputs without sacrificing yield. This can be accomplished through increasing the efficiency of inputs. This philosophy is based primarily on profitability. Our goal is to spend less money than we expect to make. The challenge is to develop a situation where efficiency of inputs is increased and to have the confidence to take advantage of it to reduce inputs to accomplish our goal of reducing production expenses.
Dr. Bill Robertson: Enhancing Adoption of Soil Health Systems – The Arkansas Experience
In this presentation to the 2019 Soil Health Institute Annual Meeting, Bill Robertson talks about the efforts in Arkansas to win over farmers to advance soil health practices in partnership with the University of Arkansas Division of Agriculture, USDA-Natural Resources Conservation Service, USDA-Agricultural Research Service, the Arkansas Soil Health Alliance, and others. (Courtesy: Soil Health Institute)
It’s hard to break our tendencies of doing the same thing we have always done.
Regenerative agriculture production in cotton requires producers to improve the health of the soil to provide an optimum environment for the plant to build a root system. The producer must also employ cultural practices to encourage the plant to focus more of its resources on building a bigger, better root system. Only when both conditions exist will reducing inputs be successful in consistently improving profitability in a regenerative cotton production system.
There are four basic practices that can be employed together to improve soil health:
Cover the Soil
These five practices implemented together help provide a boost in soil biology and changes in soil chemical and physical properties — all of which are part of improving soil health.
Producers have the potential to be more sustainable through the implementation of as few as two of these practices. While being more sustainable can benefit the environment and help provide the supply chain with responsibly produced fiber, it may not necessarily improve the profitability of the producer. Implementing all four of these practices in harmony is necessary to transition into regenerative cotton production.
The five pillars most often referred to for regenerative agriculture include the four basic practices to improve soil health, plus introduction of livestock. Livestock adds an additional level of biodiversity into the system which can further enhance soil microbe diversity, leading to more resilient healthy soils. If live animals cannot be used, many feel an alternative practice is to use animal manure.
Improved soil health is needed to be successful in transitioning into regenerative agriculture production. The interaction of soil biology with living roots helps improve efficiency of inputs. Improved soil structure is important in increasing water infiltration rates and reducing crusting tendencies. Improved water infiltration rates help capture more rainfall in the soil profile, facilitating deeper rooting and expansion of the plant’s effective rooting.
Plant competition from other cotton plants or weeds is the driving force influencing above-ground or shoot growth. As competition increases, shoot growth also increases as plants compete for sunlight. Prior to fruit development of a cotton plant, the role of mainstem leaves is to produce energy needed to develop both roots and shoots.
While development of new roots is an ongoing process, total length of roots on a cotton plant reaches its maximum point near early bloom. This is a function of the plant shifting focus of its resources from vegetative to reproductive development. As leaves and roots age, they become less productive at a time we count on them the most to mature fruit. It is important to keep the most active leaves in full sun as much as possible and to develop a root system that can help preserve and develop the desired yield potential.
Most cotton population studies show no economic benefit of planting more seed than needed to have 1.0 to 1.5 plants per foot of row on a 38- or 40-inch row at harvest. Nearly all population studies show that as plant population increases, plant height also increases. Lowering the plant population is the primary step to producing a bigger, better root system. As the plant is less focused on outgrowing its neighbor, it has more resources available to deploy in root development.
We often see the same response of enhanced root growth with cover crops seeded at lower densities. A thinner stand of a cover crop can still produce the level of plant residue needed to provide good soil coverage until canopy closure of cotton and provide the living roots needed for soil biology without the levels of biomass which can make it difficult to plant into.
The full transition into regenerative agriculture production cannot be done in one year. It may take three or more years to realize the full potential this system has to offer. It is helpful to develop a transition plan and adjust as necessary to avoid costly mistakes that can occur by trying to transition too fast.
Cover crop species selection is an important consideration. A single species selection of cereal rye — often described as the “cover crop with training wheels” — is often the first step many growers take toward incorporating cover crops into a production system because it’s easy to establish and to terminate.
Many cotton varieties have been known to produce similar yields with seed-drop rates ranging from 15K to 60K seed per acre on 38-inch rows.
With a straight cereal rye or small grain cover crop, it is often important to terminate it at late boot to full head exertion. This helps build soil biology while not creating an extreme C:N ratio of biomass to deal with in establishing the cotton crop. Soil health benefits will be seen, but not to the level needed to see full benefits of a regenerative system. To reach that level, a diverse blend of cover crops — including, but not limited to grasses, legumes, and brassicas — should be included in the mix. This diverse mixture helps make it possible to plant into cover crops prior to or at termination. Delaying termination of the cover crop can provide many benefits.
Producers have cut seeding rates to improve the capacity of the cotton plant to build a bigger, better root system and to save money without sacrificing yield. Some producers have experimented with skip- or wide-row configurations, while others have cut their seeding rate in half in solid planted configurations. Many cotton varieties have been known to produce similar yields with seed-drop rates ranging from 15K to 60K seed per acre on 38-inch rows. (Note that some varieties are less sensitive than others to different populations. Check your varieties of choice before making big changes in population.)
Cotton is very responsive to management and has a tremendous capacity to compensate. Many growers and researchers agree that a plant with a bigger, better root system has an enhanced ability to compensate. This could be a part of their lack of response with regard to yield with significant swings in plant population. Cutting seed rates can represent significant savings.
As soil health improves over time, several nutrients can be adjusted. Some feel the effective rooting zone of a plant can increase 3 to 4 times in some soils as significant changes in soil health are made. In these situations, nitrogen availability can easily exceed plant requirements. This can delay boll opening and reduce efficacy of harvest aids. Many producers feel as rooting and soil biology improve, potash and phosphorus is more efficiently obtained by the plant, offering the potential to reduce fertilizer needs.
Many growers see immediate benefits with improved soil health and continued improvement over time.
The use of the 4R strategy (Right rate, Right source, Right time, and Right place) for fertilizers to match plant needs in a sustainability program is a great strategy. As we transition into a regenerative agricultural production system, some growers feel consideration of the needs of soil microbes should also be considered with that of the plant. This transition will vary by region and soil type.
Water infiltration rates will improve as soil health improves, since the soil is less likely to crust and pore space is improved. This allows for deeper water movement into the profile, directly impacting effective rooting. Many growers see immediate benefits with improved soil health and continued improvement over time.
Pest issues are not as straightforward. Herbicide use is often one of the last things producers modify when transitioning toward regenerative agriculture production. Changes will be slow and not significant for some. The diversity that cover crops lend to the development and occurrences of beneficial arthropods in cover crops is apparent. However, little threshold data exist regarding treatment of pests as influenced by levels of beneficials. Many producers sample pests and beneficials prior to planting their cotton crop. The number of beneficials often far exceed those of pests in diverse cover crop blends. Producers often choose to preserve beneficials at planting and through the season with their management strategies. It is important to sample, know what is in the field, and make adjustments as needed.
Through the process of building soil health to provide a better environment for rooting, the efficiency of many of our inputs are improved. Encouraging the plant to allocate more resources toward development of the root system can take efficiency to another level.
The biggest hurdle facing most producers is having the confidence to plant cotton deeper than they normally would in soils with no cover. It is sometimes necessary to set the planter deeper until all seeds are in the furrow with good seed-to-soil contact. It is amazing how deep cotton can be planted and still emerge in a soil that does not crust.
Having the confidence to reduce inputs to take advantage of the improved efficiency of inputs through better soil health must be built. It is sometimes difficult to not spend the extra money on things we have always had to do. Being able to read the plant and understand what the plant is telling us will help build the confidence needed to allow us to line up on, swing, and hit our target — regenerative agriculture production.
However, the follow through after we contact our target is just as important as making contact. We sometimes lack the form for a great follow through by actually cutting inputs and increasing profitability to the level possible.
We grow cotton to make money. Our current production strategies set up a situation of cotton production like a team with one star player. The cotton plant must carry the weight of the entire team.
Transitioning toward and producing cotton in a regenerative agriculture production system gives producers the opportunity to take advantage of the teamwork available from improved soil biology, improved soil health, and a bigger, better root system. This teamwork improves the profit potential for cotton.
This production system also opens the door for other revenue streams to the producer, including carbon markets which can further enhance potential producer profitability and being able to capitalize on certified value-added programs.
Bill Robertson is a conservation agronomist living in Arkansas and former Extension Cotton Specialist for the University of Arkansas Division of Agriculture.
