Changes With Time in the Form and Availability of Residual Fertilizer Phosphorus on Chernozemic Soils

Abstract

A sequential phosphorus (P) fractionation procedure was used to measure the changes in the labile and stable forms of inorganic and organic P following single broadcast P applications to Canadian Chernozemic soils under cereal cropping. Apg1o-limately half of the fertilizer residues remained in plant-available foims (resin, NaHCor). In a Black waskada clay loam 8 yr after the application of 200 and 400 kg P ha-', residual fertilizer p consisted of resin-p, 3\ab%; HCI_P, 25_3OVo;res_ idue-P, lU-l1Vo; NaOH-P, l}-l1Vo, NaHCOT-p, l\Vo; and aggregate protected p, 3Vo.The residues in a Dark Brown Sutherland clay 5 yr after the application of 160 kg P ha-t were: resin-P, 35Zo; NaOH-p , 3040Vo; Nai{COr-p, rcn;gCl_p , USE\; Hrso4-P, 5vo; and aggregate protected p, 5vo. The soils differed in the quantity of fertilizer recovered in inorganic HCl-extractable forms. In the Sutherland soil-the change from wheat-fallow to continuous wheat cropping produced a build-up of organic P which occurred with and without the addition of p fertilizer. Stewart 1975Williams et al. 1967). Experiments to evaluate fertilizer P residues using plant uptake or extractable P in soils measure only the labile, plantavailable soil P pool and do not document the fate of all the applied P. A more complete assessment of residual P in soils would include all soil P pools, as transformations among these pools may alter the long-term availability of fertilizer P residues.The purpose of the present work was to build upon previous studies which documented the effect that large applications of fertilizer P had on grain yield and labile inorganic P pools in Chernozemic soils (Bailey etal. 1977;Read et al. 1973 Read et al. ,1977Spratt et al. 1980 (Bailey et al. 1977;Read et al. 1973 Read et al. , 1977 0' 20' 40' 80 and I 60 kg P ha-' to a Sutherland soil. The field plan, yields and nutrient uptake of this study have been described previously (Wager et al' 1986). The location, classification and characteristics of the soils used in this study were obtained from Read et al. (1977) and Souster (1979 0-, 20-, 40-,80-and 160-kg P ha-' treatments was analyzed individually to allow for statistical interpretation. Phosphorus FractionationIn this procedure (Fig. l), labile inorganic P (P,) and organic P (P.) forms are removed first, followed by more stable P forms removed with stronger extracting agents (Hedley et al. 1982

Changes in inorganic and organic Phosphorus in soil under maize (Zea mays) cultivation

“…This includes Pi present within highly crystalline oxides and hydrous oxides of iron, or in highly insoluble phosphate minerals such as plumbogummites (XAI3(P04)(OHh.H20, where X = Pb, Ba, Sr, Ca or Ce) but it may also contain occluded apatite and lattice P (Walker & Syers, 1976). The H 2 S0 4 -P fraction in the Avalon soil showed il decreasing trend from 1980 to 1992 (Table 4) in the fertilized plots (Figure 3).…”

“…soil. (Hedley et aI., .1982;Tiess~n,' S.te~~rt & Cole, 1984; .. ' Sattel &, Morris,' 1992), which is ea~ily mineraliz~ble and cohtributes t6 plarit available P (Wager et al, 1986). Cultiva': tion resulted iri a decrease in' NaHC6;~Po in the Avalon'soil (Table 4), while no general trends wei~observed in the Clov-.'…”

“…The H 2 S0 4 -P fraction mainly consisted of stable humus and humic acid, and relatively insoluble Pi forms (Wager et al, 1986;Hedley et aI., 1982). This includes Pi present within highly crystalline oxides and hydrous oxides of iron, or in highly insoluble phosphate minerals such as plumbogummites (XAI3(P04)(OHh.H20, where X = Pb, Ba, Sr, Ca or Ce) but it may also contain occluded apatite and lattice P (Walker & Syers, 1976).…”

“…According to Wager, Stewart and Moir (1986) sonication followed by a NaOH extraction, extracts the unavailable Pi and Po held within the internal surfaces of stable soil aggregates. The NaOH-\l-Pi in the Avalon soil (Table 4) decreased with time, whilst NaOH-II-Pi in general stayed unchanged in the Clovelly soil (Table 5).…”

Phosphate fertilization and phosphorus forms in an Oxisol under no-till

“…Furthermore, one must take into account the low mobility of P and the release of P-organic from plant residues in this soil layer. In Oxisols, generally P-occluded is bound to materials that are rich in iron and aluminum sesquioxides and has been traditionally considered as a fraction not readily available to plants (Wagar et al, 1986), however together with P-Fe and P-Ca, it seems to play a preponderant role in the process that keeps P available in the soil (Araújo et al, 2004).…”