The Croatian ClimateSmartAdvisors Community of Practice (CoP) on “The impact of conservation agriculture on the soil and environment” conducted secondary crop experiments in five regions of Croatia. The findings and conclusions in this Practice Abstract are based on these CoP activities.
Cover crops increase plant biomass returned to the soil and add nutrients when incorporated in green form. Their main role is to cover the soil surface and reduce the risk of erosion by wind and water, especially during periods of heavy rainfall or strong winds. When soil is covered by a main crop, cover crop, or plant residues, erosion is significantly reduced. After growth stops, leaves, stems, and roots decompose, releasing nutrients, stimulating microbial activity and soil aggregate formation, and increasing soil organic matter.
Cover crops also provide nutrients to the following crop, help break pest cycles, and contribute to reducing greenhouse gas emissions by storing carbon in the soil. Legume cover crops can fix nitrogen biologically, reducing the need for synthetic fertilizers. Some cover crops can penetrate compacted soil layers, helping the roots of the next crop develop more easily. The actual benefits depend on crop type, productivity, and the time available for growth within the crop rotation.
A farmer using this approach observed that he could enter fields earlier in spring, needed fewer passes, and used less fertilizer and pesticides. However, significant results become visible when farmers invest in new equipment and support systems. In such cases, this cultivation method becomes promising because of time savings and lower long-term input and labour costs.
This approach is especially relevant for medium and large farms and for farmers ready for major technological changes and investments. Advisors can use practical examples to show farmers how this type of soil cultivation works. The scientific community also gains evidence from a wider geographical area.
Hrvatska zajednica prakse ClimateSmartAdvisors (CoP) na temu “Utjecaj konzervacijske poljoprivrede na tlo i okoliš” provela je sekundarne pokuse usjeva u pet regija Hrvatske. Nalazi i zaključci u ovom sažetku prakse temelje se na tim aktivnostima CoP-a.
Uloga uzgoja pokrovnih usjeva je prekrivanje površine tla, što može značajno smanjiti potencijal za eroziju tla vjetrom i/ili vodom. U godinama ili dijelu vegetacijske sezone u kojima je povećana količina oborina i/ili s pojavom intenzivnih vjetrova postoji veća opasnost od erozije tla te ukoliko je tlo pokriveno glavnim usjevom, pokrovnim usjevom ili biljnim ostacima erozija tla je značajno smanjena. Nakon prestanka rasta biljaka, listovi, stabljike i korijenje pokrovnih usjeva razgrađuju se, oslobađaju hranjive tvari i potiču mikrobiološku aktivnost i stvaranje agregata u tlu i time dovode do povećanja organske tvari tla. Tijekom tog procesa, dio ostataka pokrovnih usjeva ugrađuje se u tlo kao organska tvar.
Osim navedenog pokrovni usjevi opskrbljuju hranivim tvarima slijedeći uzgajani usjev, prekidaju ciklus razvoja biljnih štetočina, doprinose smanjenje emisije stakleničkih plinova skladištenjem ugljika u tlo. Uzgojem usjeva iz porodice leguminoza koje mogu biološki fiksirati dušik iz atmosfere te opskrbiti tlo dušikom smanjuje se potreba za unosom sintetičkih dušičnih gnojiva. Neki pokrovni usjevi mogu korijenovim sustavom prodrijeti u zbijene slojeve tla, što olakšava korijenju sljedećeg usjeva lakši i potpuniji razvoj. Stvarne koristi od pokrovnog usjeva ovise o izabranoj vrsti i produktivnosti usjeva koji se uzgaja te o tome koliko vremena preostaje za rast prije pripreme ta za uzgoj sjedećeg usjeva u plodoredu.
Primjer i zapažanje poljoprivrednika koji je prakticirao ovu vrstu obrade tla je taj da u proljeće može ranije ući sa radovima u svoja polja što je za njega dosta veliki benefit ali i dobitak na vremenu je ima manje prohoda, uz utrošak manje umjetnog gnojiva i pesticida.
Značajni rezultati su vidljivi tek onog momenta kada pojedini poljoprivrednik investira pozamašna sredstva u nabavu nove opreme i prateće sustave. Tad ovakva vrsta obrade postaje vrlo perspektivna obzirom na uštedu vremena i troškove stalnih ulaganja (gnojivo i radna snaga).
Koristi od ove vrste obrade tla imaju srednja i veća što se tiče posjeda poljoprivrednih površina i oni koji su spremni na značajne tehnološke promjene i investicije u ratarskoj proizvodnji. Također savjetnici iz raznih regija mogu u praktičnim primjerom pokazati i dokazati poljoprivrednicima što i kako odraditi ovu vrstu obrade tla.
Znanstvena zajednica ima još jedan primjer ove vrste obrade tla na širem prostoru (više regija).
Cover crops, while offering numerous environmental and sustainability benefits, face challenges in controlling weeds, diseases, and pests. Traditional tillage methods, which often suppress these problems, are minimized in conservation agriculture. Therefore, it is crucial to develop alternative strategies, such as crop rotation, biological control, and precise application of plant protection products, to ensure successful production while preserving soil and biodiversity. Reduced tillage and increased crop residues can create favorable conditions for the development of weeds, diseases, and pests. The main method of weed control is mechanical destruction of weeds before the seed formation stage and this method is effective in controlling seed weeds. A greater problem is posed by rhizomatous weeds that are brought to the soil surface by conservation tillage, where they germinate, and further depletion of the nutrient reserves of rhizomatous weeds can be achieved by repeated mechanical weed control interventions. Control strategies include crop rotation, the use of cover crops and precise application of herbicides. The few trials conducted so far have shown that cover crops can be key to long-term weed control in conservation agriculture, reducing dependence on chemical agents and improving soil health. Some pests may benefit from increased crop residues, where plant cover attracts pests, while others may be suppressed by increased biodiversity. Integrated pest management, which combines biological control, crop rotation and precise insecticide application, is essential for pest management. Plant residues represent a source for maintaining the potential and source of plant disease infections, as the moisture retained in plant residues creates favorable conditions for the development of some plant diseases. Crop rotation, use of resistant varieties and biological control are important tools for disease management.
