1 / 11

Phosphorus in soils and crop nutrition

dior
Download Presentation

Phosphorus in soils and crop nutrition

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

    2. Daily phosphorus uptakes

    3. Phosphorus in soils Long-held view that phosphorus added to soil and not used by a crop was “fixed” in forms that were unavailable for use by future crops. This is no longer tenable. Reasons presented and discussed in a review: “Efficiency of soil and fertilizer phosphorus use” Syers, Johnston and Curtin. Published by FAO supported by FAO, IFA, IPNI, TFI, IMPHOS Review based on reconciling newer concepts of soil phosphorus behaviour with agronomic information. Development of a new concept of the behaviour of inorganic phosphorus in soil and its availability to plants

    4. Efficiency of soil and fertiliser phosphorus

    5. How much P should there be in the readily available pool?

    6. Examples of critical values for arable crops

    7. Similar phosphorus response curve for grassland

    8. Effect of soil organic matter on relationship between yield and Olsen P SOM Yield Olsen P % variance % t/ha mg/kg accounted for (asymptote) (at 95%) Spring barley 1.5 4.4 45 46 grain 2.4 5.0 16 83 Potatoes 1.5 44 61 72 tubers 2.4 45 17 89 Sugar beet 1.5 6.6 32 61 sugar 2.4 6.6 18 87 Grass in pots 1.5 6.5* 25 82 (dry matter) 2.4 6.5 23 96 *g/pot

    10. Efficiency of phosphorus use Long-held view that phosphorus is used inefficiently in agriculture is no longer true. If no more than 10-25% of phosphorus in the crop comes from the applied fertilizer then remainder must have come from soil reserves. Phosphorus from the soil reserves must be replaced to maintain soil fertility. Thus phosphorus in the crop and that which goes to replace the phosphorus reserves is an efficient use of the applied phosphorus fertilizer

    12. The global phosphorus resource “Peak phosphorus” How long will the global phosphorus resource last? Phosphorus is a common element, 11th in abundance in earth’s crust. Reserves (currently exploitable) reserves base (could be exploitable) – confidential information. In 2006, USGS estimated world phosphate rock (PR) reserves at about 18000 Mt and reserves base at 50000 Mt. IFA estimated world PR production at 171 Mt in 2005 At this rate of use reserves and reserves base would last 105 and 300 years, respectively , 400 to 500 years in total.

More Related