The idea of growing a crop with the purpose of benefiting others is nothing new to agriculture. Cover cropping, nurse crops, and interactions between neighboring plants has long been used and studied as means to improve agricultural and natural interactions. In this on-farm study, diverse plots were planted in the marginal field areas that are either difficult to plant, poor yielding, subject to erosion, or otherwise neglected. Planting a mixture of warm-season plants is intended to provide: habitat for beneficial insects and wildlife, flowers for pollinators, biomass for soil structure, and weed suppression through good leaf canopy cover. This qualitative research of the planted biodiversity crops will consider the establishment techniques, species selection, timing, and benefits for agriculture systems of any scale.
Plot Descriptions
Six plots were planted (totaling 6 acres of plots):
Two Field Crop Commodity Farms
One Blueberry Farm with wildlife management goals
One Blueberry and Vegetable Farm
One small acreage sustenance farm with a horse operation
Mix Planted
Buckwheat - Cool season and Summer annual that covers soil quickly and produces a flower in 70 days. For weed suppression, Phosphorus scavenging, nectar source, and soil erosion reduction due to fine fibrous roots.
Sunflower- Native summer annual. Produces large amounts of biomass and provides pollen for bees. Semi-drought tolerant and quick growing. Sunflower also provides a large root mass that is beneficial in maintaining soil structure and reducing erosion effects. Research shows a reduction in corn borer, soybean cyst, and other crop pests with sunflower production in a crop rotation.
Sunn Hemp -Sunn Hemp is a tall, herbaceous, warm-season, annual legume producing up to 120 lbs of Nitrogen and 5,000 lbs of dry matter per acre in just 9 to 12 weeks. Adapted to poor soils and has rapid growth (up to 9 ft). Potential to improve soil quality, reduce soil erosion, conserve soil moisture, suppress weeds and nematodes, recycle plant nutrients, as well as provide insectary habitat.
Yellow Sweet Clover - Biennial forming large plants with lots of biomass (up to 8,500 lbs per acre in 2 years) and having a strong taproot that breaks up compacted soils. The flowers attract honeybees, tachnid flies, and large predatory wasps. This plant is highly adapted to drought and poor soil.
Brown Top Millet- Annual, warm-season grass. Fast growing cover to suppress weeds, provide cover for wildlife and insects, reduce erosion, and prevent wind damage. Also known to suppress Root-knot Nematodes. Large seed production provides food for small wildlife.
Ratio of Mix
Buckwheat
20 lbs
Sunn Hemp
7 lbs
Sunflower
4 lbs
Browntop Millet
4 lbs
Yellow Sweet Clover
3 lbs
Filling seed mix in seed drill.
Methods
Utilizing a 5-foot, no-till drill pulled by a minimum of a 50-60 horsepower tractor, the seed mix was planted at a rate of 38 pounds per acre. The drill was adjusted and calibrated to that rate and a planting depth of about 1.25"-1.5".
Tractor pulling no-till drill to plant between power poles and the road in a non-cultivated strip.
The planting dates ranged from June 15 to June 28, 2018
The drill was followed and checked to ensure good seed placement and distribution.
Each site was chosen based on the objectives of the producer. The sites all were typically uncultivated or marginally productive.
Each site was observed weekly for 16 weeks for: germination, growth, flowering period, insect frequencies, and stand quality.
Observations
During the process of planting and growing the six plots for biodiversity, there were several observations made regarding the viability of such practices in an efficient farming system. Observations were made weekly and compared to each cooperating producer's thoughts and experience. The overall observations were focused around planting preparation, germination, stand coverage of soil, heat/drought tolerance, flowering period, and beneficial and pest insect prevalence.
A rating was given to each planting site to represent the observed stand coverage throughout the season. Based on this year's plots, the shallow-tilled soil in low land produced the quickest and most consistent coverage to reduce soil erosion, suppress weeds, and provide habitat.
Rated 1-5 (5 being greatest) for Overall Stand Coverage of Soil
Each species in the plantings was rated (1= based on overall germination across all six sites. The Sunflower, Sunn Hemp and Buckwheat germinated most uniformly across all six sites. Although, Sunn Hemp appeared to lay latent for some time and be most tolerant, during germination, to lack of soil moisture, heat, and other stresses.
Ranking Consistent Germination 1-5 (5 being best)
The following chart illustrates an overall rating of heat and drought tolerance of all six plots. The Site C was most drought resistant, however it was in bottom-land. Consistently, Sunn Hemp proved in this study to be the most drought tolerant. In two of the plots with the most sparse germination and stunted growth due to drought, the Sunn Hemp was found to outnumber all other species by 60%. Buckwheat was quick to stunt and prematurely flower in the dry conditions.
Ratings 1-5 for each species based on drought and heat tolerances observed across all six plots.
A major objective of this type of planting is to have a succession of long-standing flowers for pollinator insects. Each species was charted and the sum averaged across all sites to determine the duration of flowering. Sunn Hemp flowered the longest, but was also the last to flower, standing and flowering until frost. Buckwheat was the first to flower across all six sites, but is fairly short-lived. Millet produced a small window of flowering of just about a week. Yellow Sweet Clover was a complete loss due to drought and heat.
Average observed flowering duration in weeks, by species
Random observations and photos were taken of the plots during the growing season to record prevalence of beneficial insects and pest. Care was not taken to distinguish each species of insect, but a general rating was made at each visit to the plots. A black beat cloth (36”x28”) was used to make a quick rating of easily identified insects on the project plants.
Rating system used for insect prevalence.
List of beneficial and pest insects used to quantify and rate insect prevalence.
All observation ratings were averaged from the five observations.
It was observed that Buckwheat had a higher count of pollinators and parasitic insects. In one of the video shots, the sound of honeybees made it difficult to record quality sound. Sunn Hemp maintained a high frequency of beneficial insects and pests.
Insect prevalence was rated on a scale of 1-5 (5 being greatest prevalence) for each species planted.
The following table details the type of site and soil preparation of each plot. All no-till sites had considerable layer of residue.
Filling the seed hopper with the biodiversity planting mix.
Using a 5 foot, no-till drill to plant the seed mix at a rate of 38 lbs per acre.
Adjusting the drill to insure correct seeding rate.
Checking behind the drill to guarantee good seed placement and uniformity.
Drilling the seed in between power poles where the producer typically is unable to grow a crop. This has previously been managed by repeated treatment of herbicide.
Drainage ditch that is highly erodible along crop field.
Planting a 30 ft strip along both sides of a drainage ditch with highly erodible land.
First emergence was averaged to 10 days due to drought and planting dates. Here, you see buckwheat and millet as first to emerge.
The quick covering of an erodible and uncultivated bank between power poles in the margins of a soybean field.
Sunflower emerging. This will provide biomass, shade to reduce weed pressure, and insectary.
You can see here a diverse cover of plants to provide weed suppression and erosion, insectary, and wildlife habitat.
A Japanese Beetle is feeding on the Sunn Hemp leaf. Possible use as a pest trap crop.
Buckwheat is the first to flower providing pollen and nectar during the dirth of summer. Some Buckwheat in the planting was observed to flower at only 4 inches in height or about 3 1/2 weeks of growth.
The drought stress tendency of summer planting is a major variable to be considered. This planting was very sporadic in emergence and had considerable competition with weed pressure due to the drought in the first 3 weeks of growth.
Sunn Hemp blooming to frost. This is the planting on a drainage ditch bank in a soybean crop. Phto taken Oct 29th
Stand of the biodiversity planting the week of the first frost. This planting was crucial in stabilizing the soil through two major hurricane events.
A dense stand of buckwheat coming into bloom. Millet, sunn hemp, and sunflower plants can be seen nearly surpassing the height of the buckwheat in just six weeks.
Sunflowers blooming and being visited by butterflies.
Sunn Hemp standing 10-12 feet tall, producing enormous amounts of biomass and Nitrogen (legume). Also, this was standing after experiencing unprecedented floods and weather of two hurricanes.
Other Photos of Growing Plants for Biodiversity
Zinnias, Buckwheat, and Sunflower planted alongside vegetable crops. Photo and planting by Jerry Simpson of Waxhaw, NC
Mixture of wildflowers planted next to Sweetcorn. Photo and planting by Jerry Simpson of Waxhaw, NC
Biodiverse planting has improved the aesthetics, pollination, and pest management of the farm, says Jerry Simpson of Waxhaw, NC. Photo and planting by Jerry Simpson
Poppy species planted as pollinator and beneficial hedgerow. Photo and planting by Jerry Simpson
Mustard used as a trap crop for Harlequin bug control in cash crops. -Photo credit to Southern SARE
