Anhydrous-Schmanhydrous

Each year I come into contact with local growers that are led to believe that water run applications of anhydrous ammonia hardens the soil. They are concerned that applying this form will lead to losses in soil quality and crop yields. These beliefs are based upon opinions from those who do not understand local soil and water conditions.

I believe that water run anhydrous ammonia applications make good sense in the area irrigated by the Lower Colorado River and here are my reasons. 1. Economic Sense: The cost of ammonia historically has been 1/2 (on per unit N basis) that of other nitrogen fertilizers such as UN-32 and Urea. At my last check, the cost for NH3 was $0.35/lb N compared with $0.57/lb N for UN-32. This means a typical water run of 30 lbs N/ac of NH3 would save the farm $6.60 per acre. 2. Agronomic Sense: NH3 is a good "maintenance" fertilizer. It must convert to Nitrate before becoming completely available to root uptake. It has been said, it is the "next irrigation" fertilizer and moves into the plant over time. In this sense, it could be considered "slow release". If plant analysis shows adequate levels of Nitrogen and if the crop is entering a time of high Nitrogen demand, NH3 is a good form to apply to maintain those levels. 3. Soil Sense: NH3 does not cause hard soil where the source of the water is the Colorado River. Yes, precipitation of Calcium Carbonate occurs with applications, but the sodium hazard of the River Water (SAR) does not increase to severe or even moderate levels. Water analysis of samples taken during these water run applications show the precipitation of ~100 lbs Calcium per acre foot of water, but the sodium hazard increase(2) SAR unit 2.1-3.3 and R-Na from 1.7-2.2. Both are considered in the no restriction on infiltration category(1) with Colorado River Salinity (ECw 0.85). Therefore: Water run Anhydrous ammonia does not harden the soil in our area. NH3 is an acid-forming fertilizer, It converts over-time to nitric acid and actually reduces soil pH. 3. Environmental Sense: Yes, NH3 can burn the lower leaves where it contacts plants and roots on very sandy soils with over-application. And, NH3 is a gas and can be lost during water run applications. Therefore, I recommend neutralizing the water pH with sulfuric acid during the water run, this keeps the NH3 in solution and reduces plant burn and Nitrogen loss. NH3 is immobile in the soil and does not contribute directly to Nitrate pollution of groundwater (see agronomic sense above). Also, NH3 stimulates micro-organism growth as it is converted to Nitrate.

Safety/liability Concerns: While NH3 applications are lauded above, it must be stated that NH3 is a noxious gas and must be handled and monitored only by trained professionals. Some commercial fertilizer companies no longer supply this fertilizer because of high insurance liability costs and these safety concerns.

All considerations taken in stride, NH3 can be a good tool to have in the growers tool box to maximize production and minimize costs.

1. Soil Improvement Committee. Western Fertilizer Handbook. 9th Edition. Danville, Il; CPHA, 2002.
2. Ayers, R. S., and Westcot, D. W. Water Quality For Agriculture. Rome Italy; FAO of the United Nations. 1985

"I like numbers, words speak to some people; to others of us it's numbers."
-Carlos Slim Helu

"Problems are seldom solved by those who created them"
-Albert Einstein

Let the Rabbi Drive....

Last month I was speaking with one of my clients (we'll call him "Jeff") about a specialty crop he was growing and harvesting. Jeff had landed a "kosher" wheat deal where the crop would be grown specifically for a religious group. Without getting into the details, the client wanted the crop to be grown with special attention to detail and religious ceremony, blessing etc. Jeff had written sufficient profit into the deal to make the smaller acreage and attention worth his while.

When I spoke to him over the phone, Jeff intimated that now his client wanted to ride in the combine during the harvest of the crop, he even wanted to drive the harvestor in the field. Jeff was uncomfortable letting him do this and would draw the line there. My recommendation was to let the client ride and even drive the combine say on the trim pass of one of the fields as long as Jeff's employee rode with him. Modern combines are designed to be very user-friendly, they contain sensors and contain equipment that adjusts the conditions to thresh the wheat from the chaff. In the old days (my father's time) running a combine properly took an experienced driver setting the shakers and air flow etc.

Contract farming can have its benefits. Farming field crops is fine, but contract farming can be financially beneficial. We need to get out of the comfort zone and routine. That is, sometimes we need to let the Rabbi drive.

Unpredictable Barnyard

With the escalating prices of commercial fertilizer and the pressures from environmental regulations, more growers are turning to organic sources for plant nutrients.

It is about time! Trends in follow up plant analysis on fields that have a history of manure and those that do not show significant benefits. It is true that we can manage the nutrients using commercial fertilizers, Urea, ortho-phosphate, etc. Growers have been doing this successfully for many years. However, I have observed differences in follow up plant tissue analysis in ranches that have had supplemental organic sources applied compared to those ranches that continue on the commercial "inorganic" fertility regimes. Petiole results from the latter have a more spurious nature, the petiole graphs look more like nitrogen "EKG's". Conversely, the petiole graphs with the supplemental organic program appear to transition more smoothly from sampling to sampling over the season.

The problem is predicting when the nutrients become available from the organic sources. You may remember from your basic soils class that nitrification or mineralization occurs only in the presence of nitrifying bacteria, adequate moisture, oxygen and favorable temperatures. A complex system is at play here. I have observed adjacent fields in comparable crop rotation, manure application and soil type display very different petiole nitrate levels early in the season. One shows excessive nitrate, the other low nitrate. One requires no nitrogen application, the other a significant application.

Other observations: care should be taken when managing nitrogen with the sap nitrate quick tests. I did a petiole program on a durum wheat field about 10 years ago. The crop was grown on soils reclaimed from an old feedlot. About late jointing the basal stem nitrate levels dropped quickly and I recommended a relatively high application of UN-32 (60 lbs N/ac) to be applied in the next irrigation. I called the grower and gave him my recommendation, he was unsure of the results. He said the crop looked fine to him. We re-sampled the stems and the lab had comparable low N results. The grower applied the N and got a very good response, both visually and in the plant test. I found out later the grower was using sap nitrate quick tests on his own. Those analysis had not shown the low plant nitrogen. Our best guess was that there may have been some organic interference in those plants that gave a false positive for Nitrate in the quick tests.

Organic sources have benefits, most agronomists are schooled in the three year Nitrogen release rate of Bovine manures (33%, 33% and 25%) in the desert. Phosphate has a 2 year release rate of (50%, and 40%). The trick is to know the timing of the release of these nutrients to the plant system.

Sugarbeets and Low Plant Phosphate

For my first blog, I would like to discuss low fertility in plant analysis that is not caused by deficient soil nutrients. We have noticed in the past that low petiole phosphate may not respond to side dress or water run P applications. This has been caused by soil borne diseases and this year in Sugarbeets, by nematodes.

We have a field in the Imperial Valley that had adequate levels of P applied preplant. It was grid soil sampled and had GPS precision applied 11-52-0 prior to planting. The soil is sandy loam texture with a 1/4 mile length of run. About 2 months after establishment, the headlands began to show low petiole P (less that 1000 ppm PO4-P). We applied sufficient 10-34-0 as a water run to correct the deficiency. The petiole p did not respond in the follow up petiole samples. Soils were sampled in good and poor areas, no differences were found in extractable P (Olsen Method) and levels were adequate for good beet production.

Last week the same areas were sampled for Nematodes. Parasitic nematodes found included longidorus, stunt, and spiral.

In conclusion, the cause of the apparent low petiole phosphate was not nutrition based, it was a problem with a damaged transport system within the plant itself.