The use of green fertilizers in potato systems - what you need to know in order to plant green manure really does good and does not harm the culture.
Sidereal crops are a popular topic in crop production. Scientists and agronomists in all conduct a fairly large number of experiments with various soil protectors, publishing their findings in the public domain.
What are the siderates for potatoes: the pros and cons
So, according to one study by Dutch scientists, red clover before planting potatoes increased the yield of tubers more than a mixture of oats / peas / vetch.
However, clover is susceptible to verticillosis wilt, which is dangerous for subsequent potato cultivation. And white clover, as a precursor to potatoes, generally has a negative effect on yield.
Wild oats or wild oats, a malicious pest of cereals, unexpectedly proved to be useful for potatoes. In Argentina, a two-year experiment was carried out. Wild oats, used as a green fertilizer, had a significant impact on the yield and incidence of scab. The yield of tubers was greater, and the pressure of the scab in the pathogen inoculated areas was less.
Soy is a very good precursor to potatoes, especially in warm climates. Soy is more tolerant of soil acidity than most legumes and has worked well against scab. The disadvantage of soybeans grown as a crop is that it produces little residue and therefore does not contribute to the maintenance of soil organic matter levels.
Lupine is a favorite in Eastern Europe as a cover crop preceding potatoes.
Its effect on productivity usually lasts two years in a crop rotation. Lupine beans have an inhibitory effect on nematodes and rhizoctonia and can be an interesting choice.
In some countries, rye used to be the most popular cover or crop rotation crop for potatoes, especially on light soils. Unlike legumes, rye does not need a high pH and is very competitive with weeds. This is one of the best plants to prevent nitrate leaching in the fall. Rye is also very tolerant of low winter temperatures. Unfortunately, rye is difficult to destroy in the spring, and alas, it is a host plant for nematodes attacking potatoes.
Cabbage family crops, such as white mustard, oil radish, and rapeseed, present several advantages. They grow fast, are resistant to cold, are excellent accumulators of nitrogen, their seeds are cheap, and they die in the winter. Suppress nematodes. In addition, it turned out that mustard is effective against scab and rhizoctonia. One possible disadvantage is phytotoxicity in cool spring. Cruciferous cultures usually increase the dry matter content in the subsequent potato culture.
What do scientists say? The opinion of the agronomist
Looking at potato siderates, it would be helpful to read an article by Andrew McGuire, an irrigated crop agronomist at the University of Washington. The author calls green manure for potatoes green manure or green manure, which is quite consistent with the purpose of ground cover crops.
“Green manure is a crop that is grown and then embedded in the soil while remaining green. This practice was widely used to improve soil and provide nutrients to crops before synthetic fertilizers became available.
Recently, potato farmers have again become interested in this old technology, choosing mainly green manure from mustard to increase productivity by improving the fertile properties of the land.
However, unlike the low-profit, under-utilized green fertilizers of the past, mustard-green fertilizers require top dressing, a certain agricultural technology and, in some cases, irrigation.
They require a modern understanding of soil ecology, soil pests, plant biochemistry, as well as methods of selection and screening. It is believed that unlike synthetic fertilizers, siderates can improve the physical, chemical and biological properties of the soil.
A crop of green manure of mustard is cut and closed in the autumn before future planting of potatoes.
Physical characteristics of the soil, such as slope, water penetration, water retention and aeration, are generally improved by adding organic matter to the soil, whether it is manure, green manure, compost or crop residues. This leads to the growth of larger and healthier root systems that help plants better cope with stress.
Biological characteristics of the soil, such as microbial biomass, biological activity and biodiversity, can also be improved with green fertilizers. These changes in soil biology provide a short-term economic incentive for the use of green dung crops in potato growing systems, especially for controlling soil pests and pathogens such as fungal and bacterial diseases.
The chemical properties of the soil are optimized by increasing levels of nutrients and organic matter. When used in some growing systems, green manure is a substitute for expensive fumigants.
However, the extent and duration of these beneficial effects depends on many factors, such as soil texture, temperature and humidity, age and plant species, climate, soil cultivation methods, pest species and levels, and crop rotation. Consequently, the benefits of mustard as a siderate for potatoes vary in the fields.
The impact of green manure on soil pests is the result of several interacting mechanisms that operate in a complex chain of interactions in the soil. Therefore, it is not yet possible to say which mechanism is most important, or how each works in combination with the other - we can only determine which mechanisms may work and be important in growing potatoes.
Prior to achieving results in soil microbiology, many varieties of ground cover crops are integrated into the crop rotation system.
Proper crop rotation reduces pest problems by changing environmental and biological conditions in the field.
Each pest has a set of conditions that it prefers. If pests are allowed to have their favorite set of conditions for too long, they multiply quickly and cause problems.
In general, crop rotation with different planting dates (spring and autumn), different crops (annual and perennial; tall and short; with pivotal and fibrous root systems) and different susceptibility to pests (grass against broad-leaved weeds) becomes an important assistant to crop and potato producers including.
Soil disease suppression
The second mechanism of some ground cover crops is called biological disease suppression. Scientists see it as an observable suppression of diseases transmitted through the soil, even though the pathogen is still present in the soil on potentially dangerous ones.
Specifically on potatoes in the case of verticillary wilting (Verticillium dahliae) the researchers observed that when certain siderates (barley, mustard, rapeseed, Sudan grass and sweet corn) were planted in the soil before planting, the level of infection Verticillium was low, even with a high level of fungus in the field.
Green manure serves as an energy source for beneficial microorganisms. These organisms are thought to displace Verticilliumincreasing in quantity.
Then, after planting potatoes, they may exclude Verticillium from the area along the roots of the potato called the rhizosphere. This is the only place where verticillin wilt pathogens can affect potato plants.
Scientists believe that in the struggle for your crop, there are other mechanisms, including interference (mutual increase or decrease in the resulting amplitude) of chemical signals between pathogens and plants.
It should be remembered that dry plant residues do not work as efficiently as fresh plants. Therefore, close up the crop of groundcover while it is still green.
This term is used to indicate the effect of crop rotation or sideral crops on pests carried by soil.
Crops such as rapeseed and mustard contain biologically active chemicals called glucosinolates.
In the soil, some glucosinolates in the roots, stems and leaves break down into isothiocyanates (ITC) and other chemicals.
Isothiocyanates are known to kill or suppress certain phytopathogens and nematodes. There are many types of glucosinolates that produce different types of ITC with different toxicities for different pests.
Methyl ITC is an active chemical that also, like a regular synthetic fumigant, inhibited the growth of white rot, powdery scab and pink rot under laboratory conditions. Field trials have shown mixed results, and research is ongoing.
Sudanese grass (or Sudanese sorghum) and millet have been shown to be effective against root nematodes by producing durrin, which, like glucosinolates, forms a toxic compound when applied to soil - in this case hydrogen cyanide (HCN).
As a rule, the concentration of glucosinolates reaches its peak immediately before flowering and persists until the plants begin to dry.
Current practice is to grind green manure before applying it to ensure that these bio-fumigants mix with the soil. The best tool for this might be a high speed chopper. Finally, ITC production is more on wet soils than dry so if possible water the field after application.
This mechanism, associated with the suppression of biological diseases, occurs when certain organisms release chemicals that come into contact with plant roots and activate the plant's natural defenses.
Define goals before choosing siderates
Before you add a crop of green manure crops to your crop rotation, you must decide what you want to achieve: control a specific nematode, disease, problem weed, or simply improve the soil.
Once you have decided on the main goal, you should make management decisions to maximize the effect that will lead you to this goal.
Goal setting should take into account the unique mixture of crops, soil and pests on your farm or even in every area where agriculture is carried out.
Since certain types of green manure will be better in certain situations, you should study the advantages and disadvantages of each type of crop and try to practice those that seem to be best suited to your situation.
The success or failure in obtaining benefits from a crop of soil protectors depends on the details: planting method, planting date, seeding rate, fertilizer, weed control, as well as the method and timing of planting. Before buying seeds, make sure that you have all the information about your chosen crop.
Seeds of specialized groundcover can be expensive. Nevertheless, green manure produced using the cheapest seeds in infertile areas and with minimal watering usually does not give satisfactory results, especially in terms of combating phytopathogens and nematodes.
When considering the cost of green fertilizers, it is important to consider all the benefits. While it is relatively easy to identify benefits, if you can reduce the use of pesticides, it is much more difficult to assess the benefits of improved soil physical characteristics or other long-term benefits.
Also, remember that some of the money you spend on caring for your ground covers would have been spent anyway. This applies to fertilizers - most of them will remain in the soil for subsequent crops.
Consider the time and labor required to get good results. Will these resources be available when needed? Do you have other events at this time of the year that may prevent you from paying due attention to the green manure crop? You may have to buy additional equipment and hire workers. ”
Read more: https://www.agroxxi.ru/