A cover crop is a plant that is grown on agricultural land to cover the soil rather than for the purpose of harvesting. The practice of covering soil using a cover crop provides agricultural and overall environmental advantages. Common examples of cover crops include grasses, legumes, brassicas, and buckwheat. Nevertheless, despite its benefits, cover cropping also has potential disadvantages when done without proper knowledge of which cover crop best suits the particular requirements of the farming operation and the characteristics of a farmland.
Understanding the Upsides and Downsides of Using Cover Crops
Pros of Cover Cropping: Advantages of Cover Crops
The most common practice observed in cover cropping involves planting a particular cover crop during the post-harvest season to keep the agricultural land covered until the planting of cash crops or staple crops commences once again. However, in certain situations, several cover crops called nurse crops are planted alongside the main agricultural crop to facilitate growth. The entire practice is observed in regenerative agriculture and is used in other sustainable farming practices such as no-till farming. The following are its specific advantages:
1. Maintaining Soil Integrity and Improving Water Management
Conventional farming practices often result in soil erosion and hasten the loss of soil nutrients. Growing a cover crop during post-harvest season helps in shielding the farmland from the erosive effects of weather because it can help maintain soil structure, protect the soil surface from the elements, scatter the impact of raindrops, and reduce the velocity of water movement. Minimizing erosion means keeping soil nutrients intact.
The practice of using cover crops can also be part of an overall water management practice. To be specific, because cover cropping reduces soil erosion, it can lessen both the rate and quantity of water that drains off the field. This was documented in the research of S. M. Dabney, J. A. Delgado, and D. W. Reeves involving winter cover crops. B. A. Joyce et al. also noted that cover crops improve water infiltration and soil water storage.
2. Promoting Nutrient Buildup and Supporting Biodiversity
Another advantage of cover crops is that they not only help in retaining soil nutrients but also partake in further nutrition buildup. Plants such as legumes are considered green manure. These green manure crops are grown prior to planting main crops and are then tilled before reaching maturity to improve soil fertility. The most notable impact of these crops is in increasing nitrogen alongside other soil macronutrients and micronutrients.
Cover cropping can also create an environment conducive to the growth of beneficial microbiomes such as the rhizobia bacteria and specific nitrogen-fixing bacteria in legume root nodules. Other plants attract other beneficial animals. S. B. Cederbaum, J. P. Carroll, and R. J. Cooper noted that the use of clover as a cover crop in cotton fields attracts songbirds that help produce nutritional biomass from their consumption patterns.
3. Minimizing Pests and Diseases and Managing Weed Growth
Attracting songbirds in cotton fields helps in reducing the population of damaging insects such as caterpillars, beetles, and aphids. Saunders et al. explained in their research that excluding birds from cotton fields increased the abundance of several insect pests and reduced yield by up to 7 percent. This means that farmers can integrate biological controls in pest management through the use of cover crops that attract the natural predators of pests.
The other advantages of using cover crops in a biological control strategy include minimizing diseases and managing the growth of weeds. K. L. Everts found that pumpkins grown on a zero tillage cover crop farmland demonstrated resistance to fungal diseases while reducing fungicidal use in farming operations. The allelopathic properties of cover crops also help in suppressing weeds through the release of certain chemical compounds.
Cons of Cover Cropping: Disadvantages of Cover Crops
Nevertheless, despite the aforesaid advantages of using a cover crop in agriculture, the practice also has its issues and limitations. The resource requirements can serve as a hindrance for some farm owners and farmers. There is a need to determine which crop is best for covering an agricultural land or for using in tandem with the main agricultural crop. Cover cropping can also result in a backlash that would quash its supposed benefits. The added costs can also present a specific burden. The following are its specific disadvantages:
1. Technical Expertise and Significant Amount of Research
Selecting the most suitable plant for cover cropping a particular farmland requires substantial expertise. There are several that should be factored in. These include weather patterns and overall climate, the desired benefits or impacts, and soil characteristics. The cover crop should also be suitable for the main crop. These specific requirements involve technical expertise and a substantial amount of relevant research and other preparations.
It is also important to underscore the fact that not all plants are suitable for all climates and regions. Some cannot survive harsh winters or dry summers. Some plants become invasive or persistent in warmer or wetter weather conditions. It is important to select a particular plant for covering a field or for growing alongside the main crop in consideration of its specific advantages and disadvantages or unique characteristics.
2. Requires Additional Costs that Can Burden Some Farmers
Furthermore, apart from choosing which plant to use, cover cropping requires additional labor and management efforts. The practice also requires the purchase of seeds, equipment, herbicides, and other agricultural inputs. These translate to costlier farmland operations than conventional farming. This is another potential disadvantage of using cover crops in situations wherein farm owners or farmers have limited financial resources.
Estimates suggest that the cost of integrating this practice in an agricultural setting can range from USD 15.00 to USD 75 per acre of land. It is also worth mentioning that farmers would not be able to see the immediate results or benefits of cover cropping and specific returns on their investments. The supposed positive impacts of a particular cover crop can take several years to become noticeable and economically substantial.
3. Unfavorable Competition, Disease Risk, and Pest Sheltering
Plants compete for resources. Planting a cover crop alongside a main agricultural crop would result in competition for space, water, nutrients, and sunlight. This can decrease the productive capacity of a farmland and reduce crop yield. Allelopathic properties can also be an issue because some cover crops release chemicals that can suppress the growth of other plants. The cover crop should be compatible with the cash or staple crop.
Failure to rotate a crop for covering purposes with another crop often increases disease pressure. Some plants can harbor transmissible diseases or create a breeding ground for microbiomes that can damage main crops. A cover crop can also attract pests and provide them with a habitat for thriving and reproduction. Cereal rye crops can host certain types of insects and worms that can infest and damage the population of wheat and corn.
FURTHER READINGS AND REFERENCES
- Cederbaum, S. B., Carroll, J. P., and Cooper, R. J. 2004. “Effects of Alternative Cotton Agriculture on Avian and Arthropod Populations.” Conservation Biology. 18(5): 1272-1282. DOI: 1111/j.1523-1739.2004.00385.x
- Dabney, S. M., Delgado, J. A., and. Reeves, D. W. 2001. “Using Winter Cover Crops to Improve Soil and Water Quality.” Communications in Soil Science and Plant Analysis. 32:7-8(1221-1250). DOI: 1081/css-100104110
- Everts, K. L. 2002. “Reduced Fungicide Applications and Host Resistance for Managing Three Diseases in Pumpkin Grown on a No-Till Cover Crop.” Plant Disease. 86(1): 1134-1141. DOI: 1094/pdis.2002.86.10.1134
- Joyce, B. A., Wallender, W. W., Mitchell, J. P., Huyck, L. M., Temple, S. R., Brostrom, P. N., and Hsiao, T. C. 2002. “Infiltration and Soil Water Storage Under Winter Cover Cropping in Sacramento Valley.” Transactions of the American Society of Agricultural and Biological Engineers. 45(2). DOI: 13031/2013.8526
- Saunders, M. E., Peisley, R. K., Rader, R., and Luck, G. W. 2015. “Pollinators, Pests, and Predators: Recognizing Ecological Trade-Offs in Agroecosystems.” Ambio. 45(1): 4-14. DOI: 1007/s13280-015-0696-y