Naslov
Phosphorus chemical potential according to soil analyses by means of electro-ultra filtration

Autori
Vukadinović, Vladimir ; Lončarić, Zdenko ; Galović, Vesna ; Bertić, Blaženka ; Teklić, Tihana

Vrsta, podvrsta i kategorija rada
Radovi u zbornicima skupova, cjeloviti rad (in extenso), znanstveni

Izvornik
Proceedings of 2nd International Symposium on phosphorus Dynamics in the Soil-Plant Continuum / Rengel, Zdenko - Perth : University of Western Australia, 2003, 32-33

Skup
2nd International Symposium: Phosphorus Dynamics in the Soil-Plant Continuum

Mjesto i datum
Perth, Australija, 21.09.2003. - 26.09.2003

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
phosphorus ; chemical potential ; soil analyses ; electro-ultra filtration

Sažetak
Ability to predict status of P in soils can improve the precision of fertilizer recommendations and utilization of fertilizer P. Knowing the amounts of P reserves and dynamic in the soil can allow the farmer to apply optimal fertilizer dosage and reduce the environmental pollution with phosphate. It is desirable that soil extraction method can give the information on the soil buffer power for a given nutrient as well as about the status of other nutrients. The EUF technique predicts the short-term and long-term availability of phosphorus in the soil, giving the more detailed information concerning binding strengths, rate of replenishment, and the intensity/quantity ratios for different mineral nutrients. Standard procedure of EUF implicates the usage of temperature, electrical current and voltage in the extraction of plant nutrients, and provides data related to plant nutrient intensity and quantity. The easily available P can be obtained at 200V and 20oC within 30 min, while the subsequent extraction at 400 V and 80oC gives information on the P reserves. A thermodynamic consideration of nutrient potential, as reported previously, was used in the investigation of east-Croatian soils fertility, with the scope of better explanation of soil P status. Phosphorus chemical potential depends on soil pH value and interactions among P, Ca and Mg. These parameters, gained by means of EUF soil analyses, were used in estimation of P potential in 3763 Croatian soil samples, belonging to 10 soil types. The calculation of pP was based on the Schofield’ s expression pP = 0.5 p (Ca + Mg) + pH2PO4, where the EUF-P-I was taken into account and the ionic strength of the solution was considered equivalent to 0.02 mol dm-3 CaCl2. Theoretically, a critical pP value is equal to 7, so that soils with such pP may have adequate amounts of phosphorus for successful plant growth, but its availability to plants is limited due to other soil characteristics. A strong correlation between EUF-P-I and EUF-P-II refers to a dynamic balance between easily available fraction and reserves of phosphorus in the soil, so that only EUF-P-I could be used for calculation of pP. The calculated pP ranged between 5.94 and 6.54, and pPcor between 6.83 and 7.42, depending on phosphorus extractability and relations with pH value, texture, Ca and Mg content. Multiple regression analyses showed highly significant relations among pP, pH, selective clay content, as well as both EUF fractions of P and Ca. The pP was also significantly correlated with some other soil traits determined by EUF. The strongest influence on pP had soil pH, so that the lowest pP values, meaning the highest availability of P, were at pH value 6.5. This additional index of soil fertility can be used in the estimations of fertilizer requirement, and its calculation from the EUF data increases their interpretation value.

Izvorni jezik
Engleski

Znanstvena područja
Poljoprivreda (agronomija)

POVEZANOST RADA