Borivoj Pejić

Mutual Legume Intercropping for Forage Production in Temperate Regions

Carefully designed intercropping systems can have many advantages in comparison to monocropping such as increased forage yield, enhanced weed control, reduced soil erosion and, in the case of legumes, improved soil fertility due to their symbiosis with nitrogen-fixating bacteria. In addition the use of forage legumes is increasing for the rations of ruminants because legumes supply animal husbandry with protein-rich diets. Due to lower forage yield from perennial legumes in the first planting year and a critical standing ability of annual forage legumes, farmers tend to establish these crops with a companion crop. The first trials in Serbia studied the role an annual legume in the establishment of a perennial legume. Field pea cultivars with reduced plant height, semi-leafless leaf types and improved lodging tolerance were included together with a pure red clover stand and its mixture with oats as controls. When sown as the companion crop an annual forage legume can provide an economic yield during the perennial forage crop establishment. In average, field pea as a companion crop increases forage annual dry matter yield by 2.56 t ha − 1 and reduces weeds in red clover stand by 29%. Another group of trials involved mixtures of autumn-sown cool season, spring-sown cool season and warm season annual legumes for forage production. Here one plant had good and another poor standing ability and with concurring development stages and similar growth habit. There were economically justified intercrops with Land Equivalent Ratio (LER) values of forage dry matter yield higher than 1, such as winter faba bean with winter common vetch (1.42), spring faba bean with spring grass pea (1.44) and pigeon pea with lablab bean (1.12). The achieved results in the mutual legume intercropping research in Serbia encourage the similar research in the neighbouring West Balkan Countries and other European temperate regions.

The sensitivity of water extractable soil organic carbon fractions to land use in three soil types

ABSTRACT Soil organic carbon (SOC) has a high impact on the sustainability of ecosystems, global environmental processes, soil quality and agriculture. Long-term tillage usually leads to SOC depletion. The purpose of this study was to determine the impact of different land uses on water extractable organic carbon (WEOC) fractions and to evaluate the interaction between the WEOC fractions and other soil properties. Using an extraction procedure at 20°C and 80°C, two fractions were obtained: a cold water extractable organic carbon (CWEOC) and a hot water extractable organic carbon (HWEOC). The results suggest that there is a significant impact from different land uses on WEOC. A lower relative contribution of WEOC in SOC and a lower concentration of labile WEOC fractions are contained in arable soil compared to forestlands. Chernozem soil was characterized by a lower relative contribution of WEOC to the SOC and thus higher SOC stability in contrast to Solonetz and Vertisol soils. Both CWEOC and HWEOC are highly associated with SOC in the silt and clay fraction (<53 µm) and were slightly associated with SOC in the macroaggregate classes. The WEOC fractions were highly and positively correlated with the SOC and mean weight diameter.

Iskorišćenost prirodnih resursa Vojvodine za navodnjavanje

Znacajne povrsine plodnog obradivog zemljista dobrih proizvodnih svojstava i raspoložive kolicine vode, kao najznacajniji prirodni resursi i potencijali, cine da Vojvodina ima povoljne uslove za intenzivniji razvoj i primenu navodnjavanja. Takođe, postoje realne potrebe za navodnjavanjem jer zemljistu i gajenim biljkama tokom vegetacionog perioda nedostaje oko 100 do 300 mm vode. Sve cesce se ispoljava manjak i neodgovarajuca unutargodisnja raspodela atmosferskih padavina. Osnovu vodnih resursa predstavljaju reke Dunav, Tisa i Sava, niz manjih prirodnih vodotoka, osnovna (ukupne dužine 930 km) i detaljna (20.000 km) kanalska mreža koje pružaju mogucnost zahvatanja dovoljnih kolicina vode za potrebe navodnjavanja. Najveci deo povrsina navodnjava se vodom iz prirodnih vodotoka i kanala (preko 90%) i to najcesce vestackom kisom (80-90%). Među navodnjavanim povrsinama dominiraju oranice i baste (oko 95%) dok su ostale pretežno pod vocnjacima (5%). Navodnjavane povrsine zauzimaju ukupno 20-30 hiljada hektara. Razvojni potencijali su daleko veci.

Effects of Surface and Subsurface Drip Irrigation on the Yield, Vegetative Growth and Water Productivity of Onions

Summary The objective of this study, conducted in the northern Serbian province of Vojvodina, was to analyze the effect of surface and subsurface drip irrigation (with drip lateral placement depths of 0.05 and 0.1 m) on the yield and water productivity of onions (Allium cepa L., var. ‘Holandski žuti’). The irrigation applied was scheduled on the basis of the water balance method. The daily evapotranspiration rate was computed using the reference evapotranspiration (ETo) based on the Hargreaves equation and the crop coefficient (kc). The irrigation rate was 30 mm, whereas the amount of water added by irrigation during the season was 150 mm. According to the results obtained, the onion yield under irrigated conditions was significantly higher than that under non-irrigated (control) conditions. Differences in the yield obtained using surface and subsurface irrigation were non-significant. The amounts of water used for evapotranspiration under irrigated and non-irrigated conditions were 363 mm and 220 mm, respectively. The value of the surface irrigation yield response factor (Ky) was 0.62, whereas the values of the subsurface irrigation yield response factor (Ky) were 0.61 (0.05 m) and 0.79 (0.1 m). Consequently, onions grown from sets proved moderately sensitive to water stress under regional climate conditions and could be grown without irrigation. The value of the irrigation water use efficiency (Iwue) ranged from 3.55 to 4.97 kg m−3, whereas the value of the evapotranspiration water use efficiency (ETwue) ranged from 3.72 to 5.22 kg m−3. The highest yield of onions was obtained using a drip lateral placement depth of 0.1 m, which is recommended for high-yielding onion production.

Impact of Deficit Irrigation on Yield and Chemical Properties of Soybean Seeds in Temperate Climate

Summary The goal of this research is to determine the effects of different levels of water deficit (I100: full irrigation, I65: 35% deficit, I40: 60% deficit and I0: no irrigation) on yield and chemical composition of soybean [Glycine max (L.) Merr.] grown in Srem region of Serbia. Water deficit significantly affected the yield and chemical composition of soybean seeds. The lowest (1.63 t/ha) and the highest (3.21 t/ha) seed yields were obtained from I0 and I65 treatments, respectively. Furthermore, the highest protein (1092 kg/ha) and oil (563 kg/ha) yields were observed in I65 treatment. Lower and higher irrigation levels from I65 decreased the protein and oil yields. Our data indicated that irrigation generally increased K, P, Mg, Mn, Cu, Zn and B concentrations and decreased Ca and Fe concentrations in soybean seed. It was clearly observed that full-watered treatment (I100) provided no potential benefit in terms of soybean yield and chemical composition. For higher economic yield and good nutritional quality, water-saving treatment I65 could be suitable in soybean management in Srem region of Serbia as in other regions with similar soil and climate conditions.

Water-Yield Relations of Drip Irrigated Watermelon in Temperate Climatic Conditions

Summary The objective of the study, conducted in Vojvodina a northern part of the Serbia Republic, was to analyse the effect of drip irrigation on yield, evapotranspiration and water productivity of watermelon (Cirullus lanatus Thunb.) grown with plasticulture. Irrigation was scheduled on the basis of water balance method. Daily evapotranspiration was computed using the reference evapotranspiration and crop coefficient. The yield of watermelon in irrigation conditions (37,28 t/ha) was significantly higher compared to non irrigated (9,98 t/ha). Water used on evapotranspiration in irrigation conditions was 398 mm and 117 mm on non irrigated variant. The crop yield response factor of 1,04 for the whole growing season reveals that relative yield decrease was nearly equal to the rate of evapotranspiration deficit. The values of irrigation water use efficiency and evapotranspiration water use efficiency were 9,93 kg/m3 and 10,29 kg/m3 respectively. The determined results could be used as a good platform for watermelon growers in the region, in terms of improvement of the optimum utilization of irrigation water.