Leaf litterfall decomposition of pedunculate (Quercus robur L.) and sessile (Q-petraea [Matt.] Liebl.) oaks and their hybrids and its impact on soil microbiota

Trakas Forest is the only natural habitat of sessile oak in Lithuania. Sessile oak stand here is growing about 60-70 km from the nearest natural sessile oak stands in Poland. The purpose of this study was to determine whether autumn leaf litterfall of pedunculate and sessile oaks and their hybrids have different biochemical composition and decomposition rate and, consequently, different impacts on microbial condition of rhizosphere. For this purpose in autumn leaf litterfall C, N, P, K, Ca, Mg, lignin, ash, fat, crude fibre and water-soluble carbohydrates contents and stocks, lignin/N, lignin/P, C/N, C/P, N/P ratios, the decomposition rate and CO2 emissions were determined. In rhizosphere of studied oak species N, C concentration, pHH(2)O, C/N ratio, and dehydrogenase, urease, phosphatase, bacteria and micromycetes amount were estimated as well. The litterfall of pedunculate oak was distinguished by a higher content of lignin, higher lignin/N ratio, lower decay rate and lower carbon release, which determines decreased activity of micromycetes in the rhizosphere. Metabolic activity of microorganisms differed insignificantly among tree species rhizospheres. However, the potential for the use of carbon compound substrates and biodiversity index have a tendency to be higher in the soil under sessile oak. Lower decomposition rate of leaf litterfall and organic compounds in the rhizosphere under pedunculate oak allowed to suppose that the conditions for natural regeneration were more suitable in stands where sessile and hybrid oaks dominateAplinkotyros katedraLietuvos agrarinių ir miškų mokslų centro filialas Miškų institutasLietuvos agrarinių ir miškų mokslų centro Žemdirbystės institutasVytauto Didžiojo universitetasŽemės ūkio akademij

Mineralinės mitybos sąlygų įtaka bulvių ontogenezei

2006–2007 m. Lietuvos žemdirbystės instituto Vokės filiale priesmėlio paprastajame išplautžemyje buvo tirtas skystųjų azoto (KAS 32) ir kompleksinių trąšų (LYDERIS 9-9-9, LYDERIS 4-10-12), skirtų pagrindiniam augalų tręšimui, ir skystųjų trąšų su mikroelementais (LYDERIS SUPER, LYDERIS MIKRO), skirtų papildomai augalams tręšti, efektyvumas bulvėms. Įvertinus trąšų poveikį azoto režimui dirvožemyje, bulvienojų susiformavimui, azoto pasisavinimui, angliavandenių susikaupimui, gumbų masei augalams žydint ir visiškai subrendus bei gumbų kokybės rodikliams, buvo nustatytos tinkamiausios bulvėms tręšti trąšų rūšys ir jų paskirstymas per vegetaciją. Nustatyta, kad priesmėlio dirvožemyje vienanarės mineralinės trąšos ir skystosios trąšos KAS 32 ir LYDERIS 9-9-9 turėjo vienodos įtakos gumbų derliui, bet amonio salietra labiau nei KAS 32 mažino gumbų krakmolingumą ir skatino redukuojančių cukrų susidarymą. KAS 32 skatino nitratų kaupimąsi gumbuose. Trąšų normos dalijimas į 2–3 dozes priesmėlio dirvožemiuose yra rizikingas, nes kai trūksta drėgmės, augalai blogiau pasisavina trąšas. Papildomai tręšiant bulves mikroelementų trąšomis, gumbų derlius nedidėjo, bet didėjo didelių (> 6 cm) gumbų kiekisField experiments were carried out at the Lithuanian Institute of Agriculture's Voke Branch during 2006-2007. The aim was to study the effects of liquid fertilizers (KAS 32, Leader 9 9 9, Leader 4 10 12) intended for the main fertilization of crops and liquid fertilizers with trace elements (Leader Super, Leader Mikro) intended for additional fertilization in a sandy loam luvisol. The estimated impact of fertilizers on nitrogen regime in the soil, haulm formation, nitrogen uptake, carbohydrate accumulation, tuber mass during flowering and complete maturity stages, and on tuber quality indicators, fertilizer types most suitable for potato fertilization were determined as well as their distribution during the growing season. On sandy loam soil single-component mineral fertilizers and liquid fertilizers KAS 32 and Leader 9 9 9 were found to exert the same effect on potato tuber yield, but ammonium nitrate reduced tuber starch content and promoted formation of reducing sugars more than KAS 32. Nitrate accumulation in tubers was found to be promoted by KAS 32. Division of fertilizer rate into 2-3 doses is risky for sandy loam soils since with the shortage of rainfall at the beginning of the growing season fertilizer uptake tends to be poorer. Tuber yield did not increase through additional fertilization with trace element fertilizers, however, the content of large (> 6 cm) tuber fraction increasedVytauto Didžiojo universitetasŽemės ūkio akademij

After-effect of long-term soil management on soil respiration and other qualitative parameters under prolonged dry soil conditions

Climatic conditions of environmental zone Nemoral 2 of Europe are favorable for agricultural development. However, more frequent events of hot air-waves and prolonged droughts occurring as a consequence of climate change lead to soil moisture content reduction down to the plant wilting point. Dry soil conditions may have negative consequences for soil as a habitat. The goal of this study was to evaluate the cumulative after-effect of long-term conventional (CT) and no-tillage (NT) application in combination with or without crop residues on soil physicochemical properties, microbiological activity, and soil respiration (SR) under prolonged dry soil conditions. Long-term CT with residue returning created a soil environment that was more resistant to dry conditions than NT. Longterm CT with residue returning created a qualitative soil environment in which the main direct determinants for SR were fungal (F) and bacterial (B) community and carbon/nitrogen ratio (C/N). Slightly weaker contributors for SR were available phosphorus (PAL), plant wilting point (PWP), plant available water (PAW), and urease activity (UR); however, they acted as indirect factors. Long-term spreading of residues on soil surface under NT determined the decrease in water capacity in mesopores and micropores. Significant reduction in field capacity and PWP was revealed, while PAW remained unchanged compared to NT with residues removed. Main direct determinants for SR were F and PAL. Slightly weaker indirect contributors for SR were B, dehydrogenase, UR, and PAWLietuvos agrarinių ir miškų mokslų centro Žemdirbystės institutasVytauto Didžiojo universitetasŽemės ūkio akademij