S ciljem zaštite prirodne funkcije tla i površinske i podzemne vode, aplikacijom gnojiva u kombinaciji sa primjenom malča, stvaraju se poželjni ekološki uvjeti za maksimalne prinose, te iz aspekta samoodržive poljoprivredne proizvodnje značajno se doprinosi ekonomičnoj proizvodnji, smanjuje se ispiranje hranjiva, te time smanjuje i potreba za gnojidbom. Za rješavanje ekološke i ekonomske problematike ispiranja dušika u poljoprivrednoj proizvodnji od velikog je značaja istraživanje utjecaja malča na smanjenje koncentracije dušika u procjednim vodama s jedne strane, odnosno povećanje njegove koncentracije u tlu s druge strane. Istraživanje je provedeno tijekom 2009. godine na proizvodnim površinama OKPD Valtura, a test kultura bila je rajčica. Dvofaktorijelni pokus obuhvaćao je tri načina pokrivenosti ili malčiranja tla (golo tlo, slama, crni PE film) i tri razine gnojidbe dušikom (60 kg N/ha, 120 kg N/ha, 180 kg N/ha). Pokusnu parcelu činilo je ukupno 9 kombinacija (3 razine malčiranosti x 3 razine gnojidbe) u tri ponavljanja, odnosno ukupno 27 parcela. Ciljevi istraživanja su utvrditi utjecaj različitog načina malčiranja tla i gnojidbe pri proizvodnji rajčice na: - dinamiku i koncentraciju nitratnog dušika u površinskom sloju tla (0-30cm); - dinamiku i koncentraciju nitratnog dušika u procjednim vodama; - količine ispranog nitratnog dušika i onečišćenje procjedne vode; - prinos rajčice u danim agroekološkim uvjetima. Rezultati ukazuju da je korištenjem crnog PE filma za malčiranje smanjeno ispiranje nitrata i povećan prinos rajčice u odnosu na tlo pokriveno slamom i golo tlo, bez obzira na razinu primijenjene gnojidbe. Za dane agroekološke uvjete južne Istre preporuča se primjena PE crnoga filma i gnojidba sa 60 kg N/ha.

With the aim of protecting the natural functions of soil and surface and groundwater, applying fertilizer in combination with mulch, the desired ecological conditions for maximum yields are created, and from the aspect of self-sustaining agricultural production, they contribute significantly to the economical production, to reduce the leaching of the nutrients, thereby reducing the need for fertilization. To solve the environmental and economic problems of nitrogen leaching in agricultural production, it is of great importance to study the influence of mulch on reducing the nitrogen lost by precipitation, on the one hand, or increasing its concentration in the soil, on the other. The study was carried out in 2009 on the production areas of OKPD Valture, the test culture was tomato. Twofactor-based trials included three ways of soil coverage (soil without mulch, soil covered with straw, soil covered with black PE film) and three levels of nitrogen fertilization (60 kg N/ha, 120 kg N/ha, 180 kg N/ha). The experimental plot involved a total of 9 combinations (3 levels of soil mulching x 3 level of fertilization) in three repetitions, in total of 27 parcels. Research goals are the determination of the influence of different mulching on the production of tomato: - dynamics and concentration of nitrogen in the surface layer of soil (0-30 cm) - dynamics and concentration of nitrogen in the leaching waters - quantities of nitrogen washed and contaminated water - tomato yield The results indicate that using black PE mulching film reduced nitrate leaching and increased yield of tomato compared to soil covered with straw and soil without mulch, regardless of the level of fertilizer applied. For the agri-ecological conditions of southern Istria it is recommended to use PE black film and fertilization with 60 kg N/ha.