Critical plant and soil phosphorus for wheat, maize, and rapeseed after 44 years of P fertilization

Abstract

Phosphorus (P) crop fertilization requires optimal management to avoid the waste of a nonrenewable resource and water pollution, but current methods for assessing soil phyto-available P and plant P requirements are not sufficiently precise to meet this goal. The objectives of the present study were to (1) evaluate the effect of long-term P fertilization on the grain yield of winter wheat, maize, and rapeseed, (2) validate or establish models of critical shoot P concentration (P C ) based on relationships of shoot P concentration with either shoot biomass or shoot nitrogen (N) concentration, and (3) assess both plantbased and soil-based diagnostic tools for managing P fertilization. A long-term field experiment with contrasted P fertilizer treatments, established in 1971 by Agroscope in Changins (Switzerland), was used to measure the shoot biomass and P concentration of winter wheat in 2011, maize in 2012, and rapeseed in 2014 weekly during the growing period and the grain yield at harvest. Soil available P in the 0-0.20 m soil layer was assessed by three chemical extractions: ammonium acetate EDTA (P-AAE), sodium bicarbonate (P-NaHCO 3 ), and CO 2 -saturated water (P-CO 2 ). Long-term P fertilization increased soil available P extracted by P-CO 2 (? 24%), P-AAE (? 200%), and P-NaHCO 3 (? 155%), shoot growth and grain yield by 8.4% and 26.2% for winter wheat and rapeseed respectively but had no effect on maize. The relationships between P C and shoot biomass or N concentration were described respectively by allometric and linear models (R 2 [ 0.85, n = 21, 28 and 32 for winter wheat, maize and rapeseed respectively; slope P values for linear models \ 0.05). The P Cshoot N concentration model (slope: 0.083, intercept: 0.88) for winter wheat confirmed results from previous studies and can be used for calculating the P nutrition index. For the three soil available P indicators, threshold values needed to achieve 95% of the maximum yield for the three crops were less than those currently used in the official fertilization guidelines in Switzerland. Our results obtained after 44 years of contrasted P fertilization confirm the relationship between P C and shoot N concentration for grain crops and the need to revise P fertilizer recommendations based on currently used soil P tests.

Wheat nitrogen, phosphorus, potassium, and sulfur uptake dynamics under different management practices

“…The overall dilution rate of N in our study (b = 0.23, on average of four treatments) was about half of the b value (b = 0.44) from the critical dilution curve proposed by Justes et al (1994). While for P, our values were above the values proposed by Cadot et al (2018) (0.09 as compared to 0.04), and for S, the IM system was below that suggested by Reussi et al (2012) (0.13 as compared to 0.17) (Supplemental Table S4).…”

Molecular Speciation of Phosphorus in Soil Under Various Long-Term Fertilization Regimes

“…Compared with the NF and MN treatments, the extraction e ciencies and concentrations were higher in the P-fertilized treatments (NP and MNP) at different depths, which is consistent with the literature (Table 1; Xin et al, 2019). Our results are also consistent with the ndings of Cadot (2018) who reported that fertilization can signi cantly increase the number of results per corn plant and the weight of stems and leaves (Table 2). In the current study, higher plant height and thicker stem diameter were found after the manure fertilizer treatments (MN, MNP), but there was no signi cant difference between the unfertilized and mineral fertilizer (NF, NP) soils, which is inconsistent with previous research suggesting that fertilizer application increases the height and stem of plants (Jiang et al, 2019).…”

Nutrient stoichiometry of a plant-microbe-soil system in response to cover crop species and soil type

“…The one exception to the growth rate hypothesis was represented by the stoichiometry of P. sativum that, in sandy soil, was characterized by higher biomass C:P ratio and, although not significant, higher biomass N:P ratio notwithstanding a higher productivity (Table 1, Table S4). A possible explanation is that P stoichiometry of P. sativum was more affected by the dilution effect associated to a higher productivity (Cadot et al 2018). This is in line with the higher P concentration of P. sativum in clay soil where, notwithstanding a lower P availability (P m i n ) (Table S1), the biomass productivity was significantly lower (Table S4).…”