Precise common sense II

Elton Robinson expands nicely on the previous post by email:

The variable-rate application of inputs is actually well developed and prospering in Mid-South cotton fields. It works for two reasons. One, we have highly variable soils along the Mississippi River Delta, which in turn creates variable yields. Second, the cotton crop demands intense in-season management for plant growth, insects, weed management, disease and harvest preparation.

Infrared aerial photography and electrical conductivity mapping carts can pick up the variation in soil type when the ground is bare and pick up plant biomass when the crop is growing. Geo-referenced maps generated from the imagery allow the farmer to vary applications of plant growth regulator, defoliants and other inputs during the season based on variability in biomass. For example, the poor-yielding parts of the field will receive less plant growth regulator to allow plants to catch up with the better-yielding parts of the field, which in turn will receiver more plant growth regulator, to prevent vegetative growth. The result is higher yield and lower cost.

The cost to the farmer for the imagery, and variable-rate prescription is $7 per acre. Sprayers can be adapted for variable rate applications for $6,000. The cost of producing cotton is about $500 an acre. A conservative savings in input costs of 10 percent plus a 5 percent increase in yield would put $65 an acre in the farmer’s pocket. If he farms 1,000 acres of cotton, that $65,000, more than enough to pay off the cost of the technology in year one.

The technology is not affordable if there is little variability in the soil, or if a crop (corn, soybeans) does not respond as well to in-season management. I did read your previous blog on VR nitrogen, and agree that it's been very difficult for researchers to show a benefit.

Tech Tags: opinion farm news soil sample data lab analysis precision agriculture technology maps success edaphology science

Precise common sense

Precision ag implies computer mapped lab data and GPS controlled field equipment. Higher yields, less flying blind and easier farming. The reality is that the expense of data collection, analysis and interpretation can quickly wipeout any added value. Reading this article about variable rate management of cotton, it struck me that common sense and curiosity are the missing ingredients. Elton Robinson with Delta Press reports on cotton producer Kenneth Hood, Mississippi, who attributes his success with variable rate agriculture to, among other things, reliance on aerial photo interpretation, an approach not typical of precision agriculture. Hood says that the “... advantage to imagery is that very little data collection is required, according to Hood, “which is unlike most precision agriculture practices.” Put this experience together with the recent cryptic news on the lukewarm record of precision agriculture in Germany, which I touched on earlier, and what do you get? My sense is that Kenneth Hood is going to have lots of company.

Tech Tags: opinion farm news soil sample data lab analysis precision_agriculture technology maps success edaphology science

Farm tile drainage progressing rapidly

As told by Chris Niskanen over at the St. Paul MN Pioneer Press there is a tremendous amount of tile drainage going on in the north central USA: 100 million feet per year or about 19,000 miles by one estimate. Improved flexible drain tile is making this unprecedented rate of installation possible. The article mentions a number of areas of potential concern: loss of duck habitat and increased nitrate levels in surface water. Where no jurisdictional wetlands are being tiled, no permits are needed to perform this work. However the extent of the practice has caught the attention of folks and a community effort to address the impact of farm drainage on wetland habitat is being discussed.
Image source: South Dakota State University – Ag environmental issues page
Tech Tags: farm soil edaphology tile drainage nitrate water environment wetland habitat

Tallahassee waste water sprayfield nitrate concern for Wakulla springs

I have been following news on a 2600 acre sprayfield on the edge of Tallahassee, Florida. It is suspected of causing environmental problems 10 miles away in Wakulla Springs State Park and the Wakulla River. A recent 1000 Friends of Florida report (pdf) ties excessive hydrilla plant growth to nitrate from the sprayfield. The news this week is that the city, USGS and Florida DEP will be conducting dye tests to better understand how the groundwater beneath the sprayfield moves down gradient. I am reading the report. Striking is the relatively low (1.0 mg/l)nitrate-N needed to control the situation.

Image source: Tallahassee Democrat

Tech Tags: science farm irrigation soil edaphology eutrophication environment karst groundwater quality nitrate TMDL USGS government news

Glomalin, science, CO2 and climate change

Atmospheric CO₂ concentration is expected to increase by 50% near the middle of this century. Indications are strong that rising CO₂ effects higher soil organic carbon content in some cases. Glomalin, which accounts for 1/3 of soil carbon, is of particular interest because of its important role in binding soil aggregates and increasing nitrogen use efficiency. The Center for the Study of Carbon Dioxide and Global Change has updated their excellent summary about the CO₂ - glomalin relationship. There is a great reference list to dive into.

Image source: USDA-ARS: Glomalin: A Manageable Soil Glue (pdf brochure)

Tech Tags: soil microbiology health mycorrhizal fungi glomalin climate change global warming environmental information