In:
Biogeosciences, Copernicus GmbH, Vol. 16, No. 21 ( 2019-11-12), p. 4293-4306
Abstract:
Abstract. Here we investigated the effects of P compounds (KH2PO4 and
Ca(H2PO4)2) with different addition rates of 0, 20, 40, 60,
80, and 100 kg P ha−1 yr−1 and NH4NO3 addition (0 and 100 kg N ha−1 yr−1) on soil labile inorganic phosphorus (IP)
(dicalcium phosphate, Ca2-P), moderate-cycling IP, and recalcitrant IP
fractions in a calcareous grassland of northeastern China. Soil
moderate-cycling IP fractions, not readily available to plants but
transforming into soil-available P quickly, include variscite (Al-P),
strengite (Fe-P) and octacalcium phosphate (Ca8-P); recalcitrant IP
fractions include hydroxylapatite (Ca10-P) and occluded P (O-P). Soil
labile and moderate-cycling IP fractions and total P significantly increased
with increasing P addition rates, with higher concentrations detected for
KH2PO4 than for Ca(H2PO4)2 addition.
Combined N and P treatments showed lower soil labile IP and moderate-cycling
IP fractions compared to ambient N conditions, due to enhanced plant
productivity. Moderate-cycling IP was mainly regulated by P addition and
plant P uptake to further enhance labile IP and total P concentrations with
KH2PO4 and Ca(H2PO4)2 addition. Soil labile IP was
also directly and negatively affected by soil pH and plant P uptake with
Ca(H2PO4)2 addition. Ca(H2PO4)2 addition
significantly increased the soil recalcitrant IP (Ca10-P) fraction,
while KH2PO4 addition showed no impact on it. A significant
positive correlation was detected between soil labile IP, moderate-cycling
IP fractions and soil Olsen-P which illustrated that labile IP and
moderate-cycling IP fractions were important sources for soil-available P.
Our results suggest that moderate-cycling IP fractions are essential for
grassland P biogeochemical cycling and the chemical form of P fertilizer should
be considered during fertilization management for maintaining soil-available P.
Type of Medium:
Online Resource
ISSN:
1726-4189
DOI:
10.5194/bg-16-4293-2019
DOI:
10.5194/bg-16-4293-2019-supplement
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2019
detail.hit.zdb_id:
2158181-2
