FOR EVERY SOIL AND EVERY TECHNOLOGY
WHAT THEY GIVE US AND WHY THEY ARE WORTH THE SMALL "INCONVENIENCES"
1.Main benefits
-biological diversity
-multiple crop rotation
-weed suppression
-increase in organic matter
-stabilisation of the humus balance
-indirect influence on soil reaction
-stimulates beneficial soil fauna
-mobilizes nutrients
- "conserves" nutrients
-increases soil fertility
-improves soil moisture capacity
-improves soil structure
-optimises the pore system and aeration
-prevents erosion
-prevents soil compaction
-prevents nutrient leaching
-preserves natural soil processes
-biological control of diseases and nematodes
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2.Main characteristics of intermediate crops
-fast-growing deciduous
-with easily degradable biomass
-with a narrow C:N ratio
-to form a root system with large mass and volume
-nitrogen-fixing leguminous
-competitive crucifers
-demanding neutral plants
-drought tolerant for southern regions
-traction providing cereals when needed
-selection mainly according to crop rotation
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3.Main species
-white mustard and other mustard species
-fodder turnips, ameliorative turnips
-buckwheat
-facelia
-small-seeded legumes - clover, starflower and many others.
-large-seeded legumes - peas, vetches, lupins, etc.
-sand oats, some cereal grasses and plants
-all meeting the correct characteristics and not conflicting with the crop rotation
-world and European practice is very rich, Bulgarian list is very limited
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4.Basic selection rules
-to break the crop rotation, to be different from the main crops-root systems to use different layers
-according to technology: overwintering or frosting
-according to the soil: to break seals or provide traction
-for heavy or light soils
-for wet or dry conditions
5.Main advantages of mixtures
-biological diversity in the field-does not multiply diseases and pests in the threshold of harmfulness
-loosens the soil at different depths
-its constituent species draw nutrients from different soil layers
-there is no one-sided nutrient uptake-mutual protection and compensation of species
-under normal conditions, mixtures are always preferable; pure crops are used, for example, as a starter crop to break up very stubborn soil compacts, etc.
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6.Basic agrotechnical rules
-terms to be adapted to the biological characteristics of the species-sow shallowly in levelled soil
-regardless of the technology - after the predecessor there should be a break in capillary evaporation
-to manage the sowing - according to time, species and purpose
-whether to allow flowering - not desirable in the usual case, as the biomass coarsens, the proportion of cellulose increases and becomes less digestible by micro-organisms
-according to whether it is for ecologically oriented areas - with or without plant protection and feeding
-basic fertilisation with phosphorus and potassium for the main spring crop should be carried out before sowing the catch crop, if not carried out before another crop in the rotation
-if deeper tillage is carried out against the main crop, it should be before the catch crop
-legumes should not exceed 50% in catch crop mixtures
-mulching, composting, raining or natural frost
-avoid deep mixing/ploughing of fresh green matter with the soil
-after the catch crop has died it is absolutely necessary to interrupt capillary evaporation by cultivating even just 1 cm deep
-if overwintering catch crops are used, only leguminous species can remain in the field for as long as possible
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7.Main risks and disadvantages
-direct sowing in hot months often results in poor top dressing of the crop, compromising the crop (also applies to staple crops)-seed failure due to deep sowing and conversion to weeds for the main spring crop
-pest infestation of clean crops - plant protection may be necessary, but not acceptable for ecologically targeted areas
-inappropriate selection in the rotation may not fulfil one of their intended purposes of interrupting the pathogen pool but maintaining the infestation, e.g. self-sown wheat - fusarium...
-in mild winters to prevent frost - help is needed with appropriate tools or preparations
-underdeveloped plants do not freeze completely
-wintering intercrops may draw food and water if kept too long in the field in spring - also depends on composition
-sprouting of shoots or seeds in the main crop - this is not considered a major negative due to effective modern herbicides
-if shallow tillage is not carried out after the intercrop has died there is a high probability that the soil will become baked and dry
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SOWING OF COVER CROPS INTO THE MAIN CROP
-save the soil from weeds and evaporation-the basic rule is not to compete with the main crop
-in winter crops - frost species with moderate growth - die back and leave organics for the main crop or hitchhike with a herbicide that does not harm the main crop
-not all legumes are suitable for intercropping in winter crops
-sowing must be early enough for nitrogen-fixing tubers to form at all
-in spring crops - protect inter-rows, nitrogen fixers can help the nitrogen balance for the crop
-crops that remain until winter after main crop harvest, fields are not stripped, then frost and leave organic matter for the next crop if spring or do not compete with new sowing if autumn
-the agronomic and economic advantage of intercropping has not been proven unequivocally, each case is specific and subject to individual assessment !
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CATCH CROPS BEFORE WINTER CROPS IN BULGARIA
-the topic refers to sowing of catch crops after harvesting of rape, legumes or short-vegetation winter cereals before the main crop rape or winter cereals
-as a rule, for a good topping of such a cover in Bulgaria the rainfall is insufficient and the temperatures too high
-there are individual years with suitable conditions; a suitable approach for irrigated areas-success may have in a larger time window, i.e. before sowing a winter cereal crop; before rape the time is very short
-after early harvest sow immediately
-prefer small-seeded, drought-tolerant crops with rapid initial growth
-be different from the following crop
-not to cause problems, to be predictably destroyed by herbicides or to die back in relatively mild frosts
-and here, before sowing, not to underestimate the interruption of capillary evaporation by shallow loosening of the soil surface, so that moisture is retained for seed germination.
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For technology selection, the right judgment is based on a thorough analysis of the soil, agrometeorological conditions, field history, crop rotation, the next crop and our future intentions.
The use of catch crops is a good choice for any technology. It is not the catch crop that can fail us, it is the wrong choice of technology and machinery and not taking into account the specific working conditions.
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Wishing you success in your technology upgrade and ready to answer your questions to the best of our knowledge:
Ing. Evelina Marinova 31.03.2019