USPOREDBA AL I OLSEN PRISTUPAČNOGA FOSFORA U KARBONATNIM TLIMA HRVATSKE

The purpose of this article was to compare soil P extraction by sodium bicarbonate solution (Olsen P) and by ammonium lactate (AL P) in calcareous soils in Croatia and to create a model for predicting AL P values using the correlation of these soil tests and common soil analysis data in Croatia. Soil samples were collected, near Opuzen city, in the valley of the River Neretva, in 2005. The results of these studies confirmed significant correlation between soil P extracted by Olsen (NaHCO3) and by ammonium lactate (AL P) solution in calcareous soils from the Neretva river valley. The developed model is useful for providing fertilizer recommendations based on AL P soil-test results from Croatian soils using existing ammonium lactateextractable P calibration expecially for the calcareous soils in Croatia in the valley of the Neretva River.Cilj ovoga rada bio je usporediti količine fosfora iz uzoraka tla različitim ekstraktivnim otopinama, otopinom natrij bikarbonata (Olsen P) i amonij laktata (AL P ) u karbonatnim tlima Hrvatske te razviti model za predviđanje količine AL P na temelju dostupnih podataka o tlu. Uzorci su prikupljeni u dolini rijeke Neretve 2005. godine. Rezultati istraživanja potvrđuju prijašnjim istraživanjima utvrđenu statistički značajnu korelaciju između AL P i Oslen P metode. Razvijeni model predviđanja količine AL P na temelju analiziranih podataka o tlu može se uspješno primjenjivati za karbonatna tla u Republici Hrvatskoj, posebice u tlima u dolini rijeke Neretve

DYNAMICS OF HUMUS CONTENT AND AIR-WATER SOIL PROPERTIES IN INTENSIVE VEGETABLE AND FLOWER GLASSHOUSE PRODUCTION

Istraživanje je provedeno u staklenicima (ukupne površine 5,2 ha) u Magadenovcu na području istočne Hrvatske tijekom razdoblja od 1985. do 2002. godine. U okviru intenzivne proizvodnje povrća i cvijeća postavljen je pokus na površini od 500 m2. Kod takve proizvodnje vrlo često nije moguće obaviti oranje te se kao osnovna agrotehnička mjera, zbog povećane vlažnosti tla ili kratkoga vremenskoga roka u pripremi supstrata/tla, koristi rotokopačica, koja u jednom prohodu obavi pripremu podloge za sadnju iduće kulture. Cilj ovog istraživanja bio je utvrditi posljedice višegodišnje primjene rotokopačice te dinamiku sadržaja humusa i organske tvari u tlu tijekom 17 godina. U tu svrhu obavljene su višestruke kemijske i fizikalne analize tla, kojima je utvrđeno da se intenzivnom proizvodnjom na pokusnoj površni tijekom 17 godina istraživanja značajno smanjio sadržaj organske tvari (1995. godine - 8,60%, a 2002. god. – 5,00%) u površinskome sloju. U podpovršinskom sloju (od 35-50 cm) količina organske tvari je za oko 50% manja. Istovremeno, uz smanjivanje količine organske tvari u tlu, dolazi i do zakiseljavanja, jer su vrijednosti pH izmjerene u 1mol/dm3 KCl tijekom istraživanja niže za oko 1,4 pH jedinice u površinskom, a za oko 0,5 pH jedinica u podpovršinskom sloju te reakcija otopine tla od slabo kisele postaje kisela (pHKCl 2002. godine = 4,8). Smanjivanje količine organske tvari i humusa u supstratu/tlu dovelo je zbijanja površinskoga sloja, smanjene količine pora, odnosno narušavanja vodozračnih odnosa u tlu. Ova su istraživanja pokazala kako treba uključiti kompletni agrotehnički zahvat u obradi tla.The investigation was conducted in Magadenovac glasshouses, eastern Croatia during seventeen years (1985. - 2002.). In that period, the glasshouse production of vegetables and flowers was intensive during the whole year. The trial was set up on 500 m2. Because of often crop rotation during the same year, soil tillage must be done fast and soil must be homogenized till depth of about 40 cm. Often in practice it is not possible to plough because of numerous reasons and then main mechanization is roto-digging machine. The aim of this investigation was to determine the consequences of long-term application of the special roto-digging machine and dynamics of organic matter and humus content during 17 years. For this purpose, multiple chemical and physical analyses were done. It was determined that, by intensive production during 17 years, organic matter content in soil surface layer significantly decreased (1995 year - 8.60% and 2002 year - 5.00%). In subsurface layer (35-50 cm) organic matter content decreased by about 50%. At the same time, by decreasing organic matter content soil became more acid, because pH value measured in 1M KCl after 17 years was by 1.4 units lower in the surface layer, and by about 0.5 units lower in subsurface layer. Finally, soil became acid (pHKCl = 4.8). Decreasing in organic matter and humus content led to soil compaction, decreased soil porosity and degradation of other physical and chemical properties. It can be concluded, that it is necessary to import complete agricultural operations relative to soil tillage for soil preserving

RESPONSE OF MAIZE AND WHEAT TO INCREASING RATES OF NPK-FERTILIZATION

Stacionirani poljski pokus s rastućim količinama gnojiva NPK 8:26:26 postavljen je na kiselome tlu u travnju 2008. Primijenjene su tri stepenice gnojidbe (kg ha-1): F-1 = 103 N + 52 P2O5 + 52 K2O, F-2 = 133 N + 182 P2O5+ 182 K2O i F-3 = 183 N + 312 P2O5+ 312 K2O. Šest hibrida kukuruza uzgajano je tri godine (2008.-2010.), a nakon toga je na pokusnom polju uzgajana pšenica (sorta Renata). U našim istraživanjima ustanovljen je značajan naknadni učinak gnojidbe na prinos pšenice: 7,44 t ha-1 (F-1), 8,74 t ha-1 (F-2) i 8,43 t ha-1 (F-3). Međutim, kukuruz je reagirao nižim prinosom do 7% (3-god. prosjeci: 10,76; 10,50 i 10,02 t ha-1, za F-1, F-2, odnosno F-3).The stationary field experiment with increasing rates of NPK 8:26:26 fertilization was conducted on acid soil. Three steps of NPK-fertilization were applied (kg ha-1) as follows: F-1 = 103 N + 52 P2O5 + 52 K2O, F-2 = 133 N + 182 P2O5+ 182 K2O and F-3 = 183 N + 312 P2O5+ 312 K2O. Six hybrids of maize (the growing seasons 2008-2010) and winter wheat (2010/2011) cultivar Renata were grown in crop rotation. In our study, considerable subsequent effects of applied fertilization on wheat yields were found as follows: 7.44 t ha-1 (F-1), 8.74 t ha-1 (F-2) and 8.43 t ha-1 (F-3). However, maize responded by yield decreases up to 7% (3-year means: 10.76, 10,50 and 10.02 t ha-1, for F-1, F-2 and F-3, respectively)

COMPARISON OF AL P AND OLSEN P TEST IN CALCAREOUS SOILS IN CROATIA

The purpose of this article was to compare soil P extraction by sodium bicarbonate solution (Olsen P) and by ammonium lactate (AL P) in calcareous soils in Croatia and to create a model for predicting AL P values using the correlation of these soil tests and common soil analysis data in Croatia. Soil samples were collected, near Opuzen city, in the valley of the River Neretva, in 2005. The results of these studies confirmed significant correlation between soil P extracted by Olsen (NaHCO3) and by ammonium lactate (AL P) solution in calcareous soils from the Neretva river valley. The developed model is useful for providing fertilizer recommendations based on AL P soil-test results from Croatian soils using existing ammonium lactateextractable P calibration expecially for the calcareous soils in Croatia in the valley of the Neretva River

Effect of Inoculation and Growth Regulator on Soybean Yield and Photosynthetic Pigment Content

The main objective of this study was to evaluate the influence of soybean inoculation with different Bradyrhizobium japonicum strains and the application of Bioalgeen-S90, as a growth regulator, on photosynthetic pigment content and soybean yield. Regarding the main objective, both greenhouse experiment and field trials were conducted. The positive effect of interaction between Bioalgeen-S90 and seed inoculation with B. japonicum strain D344 on photosynthetic pigment content was determined in greenhouse experiment. The results from field trials showed a significant influence of Bioalgeen-S90 on chlorophyll b and a+b content and soybean yield. Regardless of the B. japonicum strain used, inoculation had a significantly positive effect on chlorophyll a, b and a+b content. Compared to the non-inoculated control variants, inoculation with both B. japonicum strains, showed the statistically significant effect on soybean yield. The simultaneous application of Bioalgeen-S90 and B. japonicum strains caused the highest yield increase