Rapid whole-plant bioassay for phosphorus phytoavailability in soils

Abstract

Chemical P extraction from soils is an indirect and frequently questionable index for P availability. To monitor the dynamics of P availability in soils more directly following the application of P fertilizer, manure or sludge, a rapid, whole-plant bioassay was developed using tomato (Lycopersicon esculentum Mill.), Chinese cabbage (Brassica rapa L. var. pekinensis) and wheat (Triticum aestivum L.). Plant P extracted in 0.1 M H 2 SO 4 (P i ) and total P (P t ) concentration or content in stem, leaves or whole shoots were highly correlated (P < 0.01) with P fertilizer rates or water-soluble (WSP) or Olsen P in various soils, over wide ranges of soil P status. The whole-plant P i content was found to be as informative as the more complicated indices of P t or P i concentration. The assay was used to compare availability of fertilizer-P and sewage-sludge-P after incorporation into alluvial soil during 1-100 days of incubation. While both soil and plant indices had shown that fertilizer-P was more highly available than sewagesludge-P in each period, the bioassay was much more sensitive than the Olsen-P or WSP soil indices in showing P fixation and decrease of availability during incubation time. The bioassay is sufficiently rapid (5-12 days) to allow a study of short-term changes in soil-P availability following incorporation of various P additives, and it is applicable to a very wide range of P availability values (6-535 mg Olsen-P kg )1 ), extending from lower than desired for crop production to higher than permitted from an environmental standpoint.Abbreviations: DW -deionized water; NS -nutrition solution; OM -organic matter; P i -inorganic phosphate; P t -total phosphate; WSP -water-soluble phosphorus.

Dynamics of phosphorus phytoavailability in soil amended with stabilized sewage sludge materials

“…After applying the different P sources, sludge materials or fertilizer-P, to the studied soil, P phytoavailability had changed with time. Based on the plant P i -content method (Huang et al, 2005), we found that KH 2 PO 4 applied at the rate of 150 mg P kg − 1 soil was rapidly fixed in less available forms in the soil: in terms of equivalent P fertilizer (compared to the same standard fertilizer at time zero), its P phytoavailability had decreased by 26% (to 110 mg P kg − 1 eqv.) during the first 14 days, and a further to 58% decrease (to 63 mg P kg − 1 eqv.)…”

“…Accordingly, P phytoavailability in each tested soil is given in units of mg P fertilizer equivalent kg − 1 soil (equivalent P fertilizer, mg P kg − 1 eqv.). The P phytoavailability bioassay was described in detail by Huang et al (2005).…”

Hydrolysis of glucose-6-phosphate in aged, acid-forced hydrolysed nanomolar inorganic iron solutions—an inorganic biocatalyst?

“…Therefore, understanding the behavior of phosphate ester hydrolysis is important for biology and biogeochemistry as it is relevant to phosphate availability in the environment. 2,[38][39][40][41][42][43] Recently, we discovered that hydrolysis of G6P is significantly promoted by aged, acid-forced hydrolysed nanomolar iron solutions, and the presence of some tetrahedral oxyanions in solution act as inhibitors in an order of WO 4 . MoO 4 .…”

Variation of rhizosphere bacterial community diversity in the desert ephemeral plant Ferula sinkiangensis across environmental gradients

“…These rhizosphere microorganisms obtain the carbon source and energy needed for survival from plant root exudates and litter 18 – 21 , but also provide many benefits for plants. For example, regulating the morphology and physiology of plants 22 , 23 , promote plant growth and damage repair 24 – 26 , increase plant tolerance to biological and abiotic stresses 27 – 29 , and improve plant ecological adaptability. Thus, the rhizosphere microbiome is considered as the second genome to plant condition 30 and serves on a highly evolved external functional environment for plants 31 , which are conducive to plant survival and population recovery.…”