|Camps-arbestain, Marta - Massey University|
|Shen, Qinhua - Massey University|
|Wang, Tao - Lund University|
|Van Zwieten, Lukas - New South Wales Agriculture|
|Novak, Jeffrey - Jeff|
Submitted to: CSIRO Australia Griffith NSW
Publication Type: Book / Chapter
Publication Acceptance Date: 9/22/2016
Publication Date: 3/16/2017
Citation: Camps-Arbestain, M., Shen, Q., Wang, T., Van Zwieten, L., Novak, J.M. 2017. Available nutrients in biochar. CSIRO Australia Griffith NSW. 109-125.
Interpretive Summary: Biochars are a solid byproduct produced through thermal pyrolysis of organic feedstocks. Elements contained within the pyrolyzed feedstocks contribute to the nutrient composition of biochars. Thus, biochars are being used as an amendment to supplement the soils plant nutrients levels. However, the quantity of plant nutrients in biochars should be determined beforehand especially when used with inorganic fertilizer. The nutrient value of biochars can be determined through plant yield studies in field trials or by chemical extraction of plant available nutrients. Field trials are limited in their applicability since they are soil and plant specific. A more convenient method employs specific chemicals that extract plant available nutrients. Our article outlines specific chemical extraction procedures as an alternative to field trials to determine plant nutrients concentrations in biochars.
Technical Abstract: Biochar technology may contribute to the recovery and recycling of plant nutrients and thus add a fertilizer value to the biochar. Total nutrient content in biochars varies greatly and is mainly dependent on feedstock elemental composition and to a lesser extent on pyrolysis conditions. Availability of nutrients in biochars is related to (i) the nature of the constituents to which they form part of, and (ii) their entrapment within pores. Knowledge of the amount of available plant nutrients in biochars is essential for assessing their contribution to soil fertility levels especially when added in conjunction with inorganic fertilizer. The nutrient value of biochar as a soil amendment can be determined using either (a) bioassay tests or (b) chemical methods. The bioassay tests are based on the plant yield increase on nutrient uptake under controlled greenhouse conditions or in field trials. This chemical test method to determine the contents of available plant macro- and micro-nutrients in biochars is based on either (a) the study of the amendment mineralogy, or (b) the use of selective chemical extraction. Bioassays are the most reliable methods to predict nutrient availability; however, these methods are soil–specific, plant–specific, time–intensive and cost–consuming. For the fertilizer industry, however, we suggest that chemical methods are more widely employable as an important alternative to bioassays.