One of the reasons that prompted me to switch to no-till technology was the stable lack of moisture during the growing season. On my farm, which is located in the western part of Crimea, the average long-term rainfall is 250-300 mm, and the minimum is 218 mm. An area with less than 200 mm of precipitation is already considered a desert.
The lowest precipitation is observed in spring and autumn when there are strong dry winds.
In the early years of No-till, all of the farm’s financial resources were spent on purchasing the necessary machinery, and mineral fertilizers were purchased on a residual basis. As the technology was mastered and the farm’s economy strengthened, it became possible to buy fertilizers in the amount needed to grow higher yields. But, to my surprise, a significant increase in fertilizer application did not result in the same increase in yields. The application of large doses of fertilizer coincided with the droughts that have hit Crimea in recent years. Their impact was felt both in spring and fall. In 2013, winter crops did not sprout until February.
In years with more favorable humidity, yields were higher even without fertilizers.
The crop fertilization system is one of the elements of No-till technology. In addition, plant nutrition management has its own peculiarities that traditional tillage systems do not have. With no-till technology, crop residues accumulate on the soil surface, which not only protect the soil from water and wind erosion, reduce moisture evaporation, but also help restore soil fertility. In arid climates, it is the lack of moisture that often leads to the failure of mineral fertilizers to produce the expected effect. In the driest years, which are becoming more frequent, fertilizers can even impair plant development.
How to increase the efficiency of mineral fertilizers in the arid zone?
1. Pay maximum attention to the uniform distribution of crop residues of the predecessor crop. This will allow you to accumulate and preserve even the small amounts of precipitation that fall in the fall and winter in the form of rain and snow. Where there is more moisture in the soil, fertilizers are more effective.
2. The best way to determine the nutrient requirements of plants is to analyze the soil for NPK. It will allow you to determine what fertilizers and in what quantity you need to apply to get the planned yield.
The most difficult task is to determine what yield can be planned for fertilizer calculation in order to obtain optimal economic results under conditions of possible moisture deficit.
In my opinion, you should proceed from the fact that the minimum level of planned yield for calculating fertilizer needs should correspond to the average long-term yield in your area or on your farm.
It is also possible to make more ambitious plans for yields in a very arid zone, but very carefully. You should take into account the risk of losing money on the purchase of more mineral fertilizers and even reducing the yield compared to their moderate use.
I have personally (and repeatedly) observed in neighboring farms a situation where fertilizers were applied by railroad cars, hoping to significantly increase yields. However, the lack of moisture during the growing season resulted in an even worse harvest than where no fertilizers were used at all. The high concentration of nutrients under drought conditions had a negative impact on plants.
Fertilizers are becoming more expensive every year, so the cost of a mistake for the farm’s economy is increasing. Maximum fertilizer doses in the case of moisture deficit lead to minimal results.
3. Spreading fertilizers is not very effective both for the entire No-till system and for working in conditions of precipitation deficit in particular.
The most effective way to apply mineral fertilizers in the arid zone is to apply them with seeds using a direct seeder. The design of modern seeders allows you to apply fertilizers simultaneously with sowing where they are most used by the crop. This can be done either in a row with the seeds or to the side of the seeds at a short distance and at different depths. In addition, sowing seeds and applying fertilizer at the same time saves both time and money.
4. Phosphorus in No-till technology is usually applied to the soil during sowing. I noticed that in drought conditions, phosphorus applied in the spring has almost no effect.
Therefore, the result will be achieved only in the fall when sowing winter crops. But the application dose should be calculated taking into account its use by the next spring crop.
The applied phosphorus is relatively stable and can therefore be used successfully one year after application.
5. Nitrogen. Of course, it would be ideal to apply it at different stages of development. But, as the practice of working in arid conditions shows, the best solution is to apply the entire dose of nitrogen in the fall during the sowing of winter crops. Because there is little precipitation, and nitrogen is not washed out. The best fertilizer for autumn application is urea.
It is very effective to apply nitrogen fertilizers under crop residues, but this can only be done with direct seeders.
If it is not possible to apply nitrogen fertilizers with sowing, this can also be done when the air temperature drops in late autumn by spreading them.
Another possible option is to apply nitrogen fertilizers for winter crops in the fall at a dose calculated for an average yield, and the rest of the nitrogen in the spring, at the beginning of the growing season. Here, too, the main criterion for application is not the phase of crop development, but the availability of moisture in the soil.
In the spring, if there is sufficient soil moisture, additional nitrogen fertilization can be applied. UAN is considered the best form of nitrogen fertilizer for early spring fertilization. It is applied with a sprayer equipped with special nozzles. UAN is technologically advanced and penetrates the soil more easily. If this fertilizer is not available, you can use ammonium nitrate.
This fertilization should be carried out while the soil is moist. Delaying or carrying out this operation on dry soil reduces its effect.
For spring crops, it is convenient to apply nitrogen during sowing.
But no matter how important mineral fertilizers are, especially in the first years of mastering No-till technology, in the future I plan to pay more attention to organic fertilizers rather than mineral fertilizers. Because it is organic fertilizers that not only provide plant nutrition, but also improve soil fertility. Even in the most severe drought, under the same conditions, we grow significantly higher yields on much more fertile areas of the fields.
To increase the organic matter content in the soil and improve its fertility, such elements of the No-till system as crop rotation and crop residues, and above all, cover crops (green manure) are very important.
Cover crops help to increase the organic matter content in the soil, stimulate soil nitrogen production and microbiological activity, and increase the moisture retention capacity of the soil layer. The introduction of cover crops into the crop rotation improves soil health and reduces the cost of mineral fertilizers.
The most common practice of growing green manure under no-till is to sow cover crops separately or (even better) in mixtures of different crops after harvesting the main crop. In the event of drought, there is a high risk of not getting seedlings, so an alternative is to grow binary crops (i.e., several crops at the same time).
In the arid zone, drought-resistant legumes such as vetch, sainfoin, and sweet clover can be successfully used in binary crops. And sowing cover crops in the spring, when the soil is moist, is the key to getting seedlings.
After the main crop is harvested, living roots remain in the soil, and a vegetation cover remains on its surface.
In addition, in binary crops, the weight of worms per 1 hectare reaches up to 40 tons. Isn’t this a super task?
In a very arid zone, the future lies in such a fertilizer system using direct seeding technology. However, I understand that each farmer develops his own plant nutrition system depending on the moisture conditions, fertilizer types, machinery and even the availability of labor.
The best way to manage plant nutrition is the one that is most effective not only for each individual farm, but also for each specific field