- Agronomic: grass (misc. perennial)
- Animal Production: rangeland/pasture management
- Soil Management: soil quality/health
In response to the negative impacts of NPK on soil and climate, there has been an increased interest in organic
growing methods. One of these is the use of biostimulants, which the 2018 US Farm Bill described as compounds
or organisms that stimulate natural processes to enhance growth, yield and fertility.
During the last three years we have studied the effects of the micro-application of a live, green algae, Chlorella vulgaris.
In a SSARE funded study last year, we tested its effects on tomatoes and found that yield was higher in rich soil (treated
with compost), and in poor soil (not composted). In previous turf trials we observed improvement in measures of
soil fertility including organic matter, soil respiration, and soil organic nitrogen (Haney testing).
A recent study conducted by an affiliated farmer in Nebraska found increased hay production (sorghum hay) with the
addition of algae to his usual NPK input. Of particular interest was a 75% increase in protein content, and a 30% rise in
lipids. Of concern was a marked increase in nitrate content with algae treatment. After consultation with his nutritionist,
we conclude that adding algae to a large dose of synthetic nitrogen is too much.
In this study, we will analyze nitrates in pasture grass to determine nitrate content with reduced nitrogen input, and no input.
This study is designed to determine whether algae treatment would be enhanced with the addition of a small quantity
of NPK (25% of the usual input), or the addition of a carbon source such as biochar.
The following study conducted on horse pasture addresses those issues.
Project objectives from proposal:
The study will be conducted at the Iron Horse Farm (IHF) on Johns Island, SC. For 18 months, algae has been the
only nutritional input, and the horse farm owner, Allen Reed has been satisfied that quality of the pasture, and
particularly the color of his grass has improved (multiple studies have shown increased chlorophyll with algae treatment).
The study will be conducted in four contiguous sections of pasture measuring 1-2.5 acres.
Sections will be treated as follows:
Pasture 1A: (nearest Bohicket Rd): Algae (Chlorella vulgaris)+ 25% NPK
Pasture 2A: Algae alone
Pasture 3A-north half: Algae alone
Pasture 3A-south half: Algae + Biochar
Pasture 3B-north half: Algae alone
Pasture 3B-south half: Biochar Alone
A single application of NPK, based on 25% of the recommendations based on soil tests, will be administered
with the emergence of perennial grass (Bahiagrass) in the early spring, usually the second week in March and
again as needed based on sufficient forage required by grazing horses.
A single application of biochar will be applied at the same time, as will the first application of algae. A second
application of algae will be added 2 weeks later, then at 4-week intervals through the growing season.
1. Growth: The first assessment will be when the Bahiagrass is well established.
After a first mowing, it will be unmowed until the first test-section reaches 5 inches in
height. At that time the height of grass in all of the test sections will be measured.
Grass mowed from a 20 x 20 foot representative plot in each test
pasture will be weighed.
2.Chlorophyll: levels of chlorophyll a and b will be assessed (Regen Ag Lab, Pleasonton, NE).
3.Nutritional content: standard analysis will include crude protein, nitrates, fat and minerals.
4.Haney soil testing (baseline and 2 weeks after the third algae application, or 6 weeks