Potrzeby nawożenia fosforem roślin uprawnych w zależności od zdolności gleb do sorbowania fosforanów
AbstractThe main objective of the study was to assess the usefulness of phosphate sorption properties as a basis for formulating the P-fertiliser recommendations in crop management. The experiments were conducted in the years 2001-2006 in the greenhouses and laboratories of the Faculty of Horticulture, Agricultural University of Krakow. The experimental design was as follows: • Experiment I (laboratory): determining the phosphorus sorption characteristics, single-point P-sorption indexes, and phosphorus sorption isotherms (by incubation method) of 36 soils widely varying in physical and chemical properties; and determining the effect of incubation time and liming on the P-sorption proper¬ties of soils; • Experiment II (laboratory): establishing the rate of phosphorus for a single--point P-sorption index; n Experiment III (greenhouse): verifying the usefulness of the single-point P-sorption index in the pot growing of ryegrass on five soils (limed and non--limed) chosen in Experiment I; • Experiment IV (greenhouse): verifying the usefulness of the single-point P-sorption index in the pot growing of spinach on 5 soils (only limed) chosen in Experiment I. To ensure a wide variability of soil properties, the samples for the laboratory experiments were taken from the upper layers (0-30 cm) of cultivated soils representing 36 different sites in southern Poland. The five samples of soils selected for the greenhouse experiments varied greatly in P-sorption capacity. The reactions between phosphates and soil were studied by incubation method with various rates of phosphorus added in the form of Ca(H2PO4)2 and two durations of the incubation period (7 and 30 days). Single-point P-sorption indexes were determined using a solution-to-soil ratio of 20 : 1 (5 g of soil, and 100 cm3 of 0.02 mol dm-3 KC1) with 5 initial concentrations of phosphorus for each soil sample: 20, 40, 80, 160 and 320 Ag P • dm-3 (200, 400, 800, 1200 and 1600 mg P • kg-' soil). Three methods: universal (P extracted by 0.03 mol • dm-3 CH3COOH), Egner¬-Riehm (P extracted by ammonium lactate), and a method with 0.01 mol • dm-3 CaC12 were compared for applicability to predict the plant-available phosphorus content of soil. The relative effectiveness (RE) of P-added was assessed on the basis of the yield of fresh and dry matter of plants, the P content of the plant tissues, and the results of soil P-tests. As found in the study, the single-point P-sorption indexes PSI1500 (Bache index), IPEC (Serrano index) and PRI200 (Allen and Jeffrey index) define well the P-sorption isotherms, so they could be used as a tool for quick routine estimation of the P-sorption capacity of soil. All the indexes estimating or predicting P-sorption capacity were closely related to one another. Irrespective of liming, the capacity of soil to adsorb phosphorus decreased with the increasing rate of P added during incubation. The availability of phosphorus added to soils (P dissolved by 0.03 mol • dm-3 CH3COOH) decreased with time after P-fertilisation. In the incubation period, two phases of phosphate reactions with soil were identified: a phase with fast-falling phosphate solubility, which finished after 24 h of incubation, and a phase with slow-falling phosphate solubility, which lasted for 3-6 months after fertilisation. The mean values of the P-sorption indexes estimated by incubation method (%SP-7, 7-day incubation) were related to the concentration of available P in soils determined by universal method (Pu), and were 88.4% for soils with very low Pu level (< 10 mg • dm-3 soil), 84.0% for those with low Pu level (10-20 mg • dm-3 soil), and 77.6% for soils with sufficient level (21-50 mg • dm-3 soil). The AEP value (slope of the curve depicting the relationship between the rate of P applied and the P concentration in soil determined by universal method) decreased during incubation in non-limed soils, but not in limed ones. Based on the positive correlation of the IP4,30 index with the clay content and titratable acidity, and its negative correlation with the available P content of soil determined by universal and Egner-Riehm methods, the best rate of phosphorus for determining the single-point phosphorus-sorption index was found to be 400 mg P • kg-' soil. Therefore, this index was chosen for the study with ryegrass and spinach in greenhouse experiments. In the greenhouse experiments with ryegrass and spinach, the relative effectiveness of P fertilisation was best for soils with a low P-availability status and a high value of IP40„. The IP400 index was negatively correlated with the rate of P added to soils and the phosphorus concentration in the plant tissues. Liming increased the concentration of available phosphorus in soils, estimated by the universal and Egner-Riehm methods (except the soil from Gd6w). Based on the results of the study it is suggested that the phosphorus-sorption index IPA, could be used in preference to other methods as a tool for optimising the P-fertiliser recommendations for agricultural practice. Besides being easier to determine, it would also provide a more specific and relevant measure of phosphate buffer capacity, as shown by its high correlation with phosphorus sorption parameters for the group of 36 soils. Hence, the index deserves wider application.
|Other language title versions||Phosphorus sorption properties for optimising P-fertiliser recommendations in crop production|
|Publisher||Uniwersytet Rolniczy im. Hugona Kołłątaja w Krakowie, MNiSW |
|Publishing place (Publisher address)||Kraków|
|Book series /Journal (in case of Journal special issue)||Zeszyty Naukowe Uniwersytetu Rolniczego im. Hugona Kołłątaja w Krakowie. Rozprawy, ISSN 1899-3486, (0 pkt)|
|Publication size in sheets||10.5|
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