Strip-Tilling Tips and Tricks

Alex Tiller - Thursday, March 05, 2009

Spring is on the way, and that means farmers are thinking about tilling the fields for the spring crops. Longtime readers know that despite my last name, I have been a strong advocate for no-till and strip-till systems of soil management. Strip till is a good compromise that gets the benefits both of conventional tillage (warming and drying the soil) and no-till (protection of soil quality). Here are some strip-tillage best practices that may come in handy when you hit the fields.

You probably will be applying anhydrous ammonia when you prepare your strips to provide an N boost – that should be limited to 100 pounds of actual N per acre at most in a strip till field. Since you’ll be planting along the tilled strip, wait about two weeks between your ammonia application and planting to prevent salt injury to your seeds and seedlings.

You can skip the ammonia and apply liquid N directly during your spring tillage, or you can use urea as an N source – if you use urea, separate it from the seed line by three or four inches. If you do use ammonia, place it about eight inches deep and use packer wheels to break up lumps in the soil and to reduce volatility. If you need more N, you can apply it via the irrigation pivot.

P and K applications are also commonly deployed while doing strip till passes. Place P and K between three and six inches deep to prevent erosion but still leave plenty of nutrients available for uptake. Starter fertilizer can also go into the strip till – put it about 2.5 inches deep and 2.5 inches away from the seed line to avoid fertilizer burning the seeds and seedlings.

The Probability of Profitable Farming: Stack the Deck

Alex Tiller - Tuesday, February 10, 2009

From time to time I ask experts in certain fields to provide us with their thoughts and insight.  I recently asked Dominique Depaz, an analytics consultant to the agricultural industry, to share his process and insight on risk analysis and crop selection.  I found it intriguing and have provided his words below.


It is my observation that farmers are by far the greatest gamblers on earth, willing to put their entire assets on the auction block season after season; and yet they are highly risk adverse when it comes to changes in cultural practices. Most grow the same way over and over, (expecting different results); or follow a few mavericks willing to share their success stories.

Why is that?

I think part of the reason is that many farmers do not keep good data. And that is understandable. When harvest season hits, there is no time for anything else but to get the grains or vegetables off the fields. Who has time to track yield from field to field? But image the strategic value of data going back twenty two or more years? I am talking about weather information such as rain, wind, solar index on the farm, yield by fields, seed varieties, fertilizer applications and chemicals applied and pricing for the commodity.  This information can be extremely valuable on two fronts: first for planning purposes and secondly for changing cultural practices.

Planning Purposes

Data mining can be extremely useful in developing risk probabilities and as a result it can guide a farmer’s planting schedule, type of crop to rotate and changes in farming practices. If you have thirty or more years of data from your farm, in a spread sheet you can analyze your yields relative to prices, weather and changes in growing practices. Even a few years can be very helpful. For example, you would discover that at the bottom of every eleven year solar cycle a La Nina event is likely to occur. This may cause droughts or excessive rains depending on your location. An El Nino event would have the opposite effect. You could then compare your yields during those periods and see how you fared in terms or production and in terms of market prices. Did the climatic change cause prices to move and by how much?  You may find that droughts may have a huge impact in your region, but because the commodity you produce is also grown in other regions of the country, there is no significant change in price. Conclusion: you would loose money growing this crop with no chance to make up the losses at a later date. The strategic question then is: Can I grow an alternative crop which would fare better under the probable circumstances?

I have found that a simple probably matrix can be very useful. Here is how to develop it:

Based on your yield data, price and weather, you assign probabilities across a spectrum. After reviewing your data you may find that if you get more than six inches of rain within a week, you will loose 50% of your crops, whereas if you get three inches, you will loose less than 20%. Likewise the price of your commodity goes up 10% in the first case and only 2% in the second. Now, based on where you are in the solar cycle, you can go back several cycles and see how well wind and rain data correlated and you can make a projection that, for example, there is a 30% chance of getting six or more inches of rain within a week during the season, a 60% chance of three inches and a 10% of no rain. Of course you can break these probabilities further to obtain a smoother curve.

The final probability will look like this.

(0.50 (crop damage) X 0.30 (chance of 6” of rain) x 0.10 (price change) + (0.20 (crop damage) x 0.60 (chance of 3” of rain) x 0.02) + (0.10 (crop damage from drought) x 0.10 (no rain) x -0.05 (drop in price)* = 0.0169 or 1.69% financially better.

Note: * to mean that even though the farm had a drought the commodity price went down 5% because other areas of the country or other regions of the world over produced.

You may argue that this is a meaningless exercise, but it is not and I have used it many times to determine if it makes financial sense to replant after a frost, or a devastating rain, or early season drought.

Changing Cultural Practices

I have found that one of the reasons many farmers are slow to embrace yield enhancement products or to even trial them aside from not keeping good data is the belief that there are too many factors at play and the factors can not be differentiated.

One of the statistical tools used by researchers to overcome this issue is multiple regression analysis, which is available in an Excel spread sheet. For example, this analysis allows you to compare yield, against many variables such as rain fall, seed variety, wind, day light hours, growth enhancement products, disease etc.; and to factor the contribution of each variable to yield. As a result, a farmer can very precisely determine how effective a new product is in spite of changes in weather and other factors.

Most extension agents are familiar with this statistical tool and can help farmers set up trials and interpret the data for them. From experience, I have used this approach and have trialed and altered cultural practices each year based on this analysis. Multiple regression analysis is a very powerful tool which allows a farmer to determine what works with a high degree of confidence.

Farming by the numbers may not alter the risk of farming. Weather, disease, market prices and other factors beyond the farmer’s control drive the outcome. However, analyzing the risks and formulated alternative plans can have a very positive impact on the farmer’s bottom line.

~Dominique Depaz


Originally from Martinique, Dominique Depaz comes from a family of banana, pineapple and sugar cane growers. Right out of college he was among the first designers of drip irrigation systems in the western hemisphere. He then joined the Navy and flew jets aboard carrier for many years. Dominique has owned numerous businesses in and out of agriculture and has written many risk analysis software and a very complex, task driven farm management software. He is currently an analytics consultant to the agricultural industry.  Dominique can be reached at: Dominique (at) SmartFarmingSolutions (dot) com

Believe the Science, NPK Cost Reductions

Alex Tiller - Thursday, January 08, 2009

As I’ve reported here a number of times, input prices for farmers have been rising steadily. If the economy collapses, we can expect those prices to decline – but commodity prices will also likely decline in that eventuality, leaving farmers in the same boat. If the economy recovers – everybody cross your fingers – then inputs are likely to continue increasing as a share of farm operational costs.

With that in mind, many farmers have begun exploring their options regarding fertilizer use, with an eye toward reducing use to the necessary minimum. While this can save quite a bit of money, it is important for farmers to be aware of the risks of reducing fertilizer inputs beyond a certain point. Most farms probably do have some “slack” in the fertilizer budget – but it’s critical not to cut out too much. Suboptimal fertilization levels can have detrimental impacts on yield, stress tolerance, and standability of crops.

One principle to follow – believe the science. Soil tests provide hard data, not just a general “feel” for how soil is developing, and should be done by any farmer planning a reduction in fertilizer input. Don’t assume that a test result will stay valid over time, however – remember that every plant harvested is taking some nutrients out of the soil. Even if your soil has a buffer of built-up fertilizing agents that might allow you a light year for new applications, that won’t necessarily apply during the next growing season.

Another thing to bear in mind is that different crops remove nutrients at different rates. Just one bushel of corn removes 0.29 pounds of K2O and 0.4 pounds of P2O5, while a bushel of soybeans on the same land will remove 1.45 pounds of K2O and 0.85 pounds of P2O5. Know the figures for the crops you intend to grow, and take that into account in your fertilizer plan.

Aside from direct fertilizer use, remember that pH levels will have an impact on the bioavailability of existing (and added) nutrients. If you fail to apply enough lime, absorption rates for N, P and K can decrease, sometimes dramatically. The pH must be 5.9 or higher for N and K, and 6.4 for P. A low pH level can also increase the risk of herbicide carryover for imidazolinone-based applications.

The consequences of low fertilizer levels can be quite devastating to a crop, particularly if the weather doesn’t cooperate. Insufficient P doesn’t produce many immediately visible effects, which may lead you to conclude that levels are adequate, but P levels directly affect the ability of your plants to handle stress. Insufficient K levels mean that plants have a harder time absorbing water and nitrogen from soil, which makes the crop more vulnerable to drought conditions. In soybeans, inadequate K can cause reduced nodulation and increased damage from disease and pests.

To summarize, decreasing your fertilizer application may well decrease your cost – but it may not improve your bottom line if you aren’t careful. It doesn’t make sense to knock $50,000 off the fertilizer bill if it means your stunted crop brings in $60,000 less than last year. Check soil levels carefully and accurately calculate the nutritional needs of your planned crop before taking this step.

Corn, cows, and poop. Smells like...profit

Alex Tiller - Wednesday, October 22, 2008

You know how much residue is left on the field after you harvest a corn crop (you can probably look out the window and get a good idea), but did you know that the residue amounts to about half of the total crop weight? That’s right, 50% of the biomass you grew is still sitting on the field after harvest.

That corn residue can be used as a winter feed source for beef cattle, squeezing another use out of the crop and greatly cutting winter feed costs for combined operations. One acre of corn residue is about two months of feed for a 1,000 pound animal. Getting the most value out of the residue requires a little planning and some awareness of what can go wrong, however. It doesn’t save you any money if you end up with a beef herd with nitrate poisoning, or if the vet bills for foundered cows exceeds what you saved in feed.

To get the most out of the nutrition left on the field, animals should be allowed to graze immediately after harvest, as wind and rain quickly break down the nutritional quality of the residue. Cows can get about 65% total digestible nutrients, and about 7% of crude protein, from corn residue. Depending on the age and breed of the animals, you might need mineral supplementation to keep them healthy while they’re foraging on your corn fields.

Over the course of that 60-day feeding window, the cows will only eat about 20% of the residue – and you thought your kids were picky eaters! That’s actually good news, as it means that erosion and soil compaction will be greatly limited by the large amount of biomass that will be left on the ground. Compaction caused by hooves is usually limited – but just as with a tractor, wet soils will compact more and you might want to bring the herd back inside if the soil is damp, especially if you already have soil compaction issues on that field. Frozen ground is generally well-protected against compaction by animal hooves.

If you had a dry year, then the lower stalks (which comprise a large percentage of your residue biomass) are likely to be high in nitrates. That can cause nitrate poisoning in animals that feed on them – be careful about grazing on fields that suffered drought. Nitrate levels will break down over time, though, so you don’t usually need to worry about what happened in prior years. In addition, if there is grain on the field as well as corn, be sure that your cows get hay or other feed before they get at the grain to prevent foundering.

Not only does residue foraging save you money on feed costs, it also cuts your fertilizer bill for the next season. Cows like to eat, and eating has a natural consequence – and that 1,000 pound cow is going to drop about 63 pounds of “natural consequence” on your field every day. Be sure to take that additional fertilizer into consideration when designing your fertilizer strategy for next year.