Determination of Plant Available P in Soil

Abstract

Fertilization should be based on a proper diagnosis of the plant nutritional status. Without, there is always the risk of under fertilization causing economic losses by not exploiting the yield potential of the site and its crop. On the opposite, over fertilization not only hampers fertilizer economy through inefficient nutrient rates, but also causes serious environmental impacts on neighboring ecosystems. There are four basic diagnostic methods each of which has its advantages and disadvantages: ceteris paribus fertilizer trials are complicated and time consuming delivering results far too late for fertilization planning. Visual assessment is fast but requires experts eyes and works only for a few nutrients and only when severe nutrient deficiency occurs. Plant analysis is accurate, however, bound to well defined growth stages, but shows only the actual stage of supply with little information about available reserves in the soil or growth media and is also too late with its results for practical fertilization. Last but not least: analyzing the soil can be independent of crop development, well in advance to contribute for the fertilizer design for the actual crop and offers insight into the reserves in the substrate. However, its value for fertilization planning is strongly depending on the quality of the calibration of the results. Of all essential plant nutrients phosphorus is the one for which the most and intensive research work on assessing soils has been conducted in the past. This chapter introduces the basic conceptions of soil analysis for plant available P, provides an overview on available methods and discusses their advantages and disadvantages.

Combining diffusive gradients in thin films (DGT) and spectroscopic techniques for the determination of phosphorus species in soils

“…Hence, several simple chemical extraction methods are used to estimate the plant-available P of soils [1,2]. More recently, several research groups [3][4][5][6][7][8] have shown that the Diffusive Gradients in Thin films (DGT) technique have a much better correlation to plant-available P in soils than standard chemical extraction tests (e.g.…”

The equivalence of the Calcium‐Acetate‐Lactate and Double‐Lactate extraction methods to assess soil phosphorus fertility

“…Although, compared with other widely used P extraction methods (e.g., Olsen, Mehlich, or Bray), CAL and DL are quite similar, there are differences that influence the comparability of both methods (Yli-Halla et al, 2016). Because of the higher pH value, CAL extracts a smaller portion of Ca-P, but a higher portion of Al-and Fe-P (Reichert, 1989;Yli-Halla et al, 2016).…”

“…Phosphorus in soils can be separated into various fractions with different chemical properties (e.g., solubility, mobility) and different availability to plants (Cross and Schlesinger, 1995;Frossard et al, 2000). Only a relatively small fraction of total soil P is readily available for plant uptake (Frossard et al, 2000;Neyroud and Lischer, 2003;Yli-Halla et al, 2016).…”

Effects of thermal drying on phosphorus availability from iron‐precipitated sewage sludge

“…The DGT technique has increasingly been acknowledged as superior for assessing soil P status in comparison with traditional extraction methods (Yli-Halla et al, 2016), and the method has also been suggested to be a useful method for predicting the growth response of plants to added P fertilizers (Six et al, 2013). Comparison of the ability of the DGT method and the more simple WEP method for their ability to predict plant P availability is therefore of interest.…”