TY  - JOUR
U1  - Wissenschaftlicher Artikel
A1  - Horf, Michael
A1  - Vogel, Sebastian
A1  - Drücker, Harm
A1  - Gebbers, Robin
A1  - Olfs, Hans-Werner
T1  - Optical spectrometry to determine nutrient concentrations and other physicochemical parameters in liquid organic manures : A review
JF  - Agronomy
N2  - Nutrient concentrations in livestock manures and biogas digestates show a huge variability due to disparities in animal husbandry systems concerning animal species, feed composition, etc. Therefore, a nutrient estimation based on recommendation tables is not reliable when the exact chemical composition is needed. The alternative, to analyse representative fertilizer samples in a standard laboratory, is too time- and cost-intensive to be an accepted routine method for farmers. However, precise knowledge about the actual nutrient concentrations in liquid organic fertilizers is a prerequisite to ensure optimal nutrient supply for growing crops and on the other hand to avoid environmental problems caused by overfertilization. Therefore, spectrometric methods receive increasing attention as fast and low-cost alternatives. This review summarizes the present state of research based on optical spectrometry used at laboratory and field scale for predicting several parameters of liquid organic manures. It emphasizes three categories: (1) physicochemical parameters, e.g., dry matter, pH, and electrical conductivity; (2) main plant nutrients, i.e., total nitrogen, ammonium nitrogen, phosphorus, potassium, magnesium, calcium, and sulfur; and (3) micronutrients, i.e., manganese, iron, copper, and zinc. Furthermore, the commonly used sample preparation techniques, spectrometer types, measuring modes, and chemometric methods are presented. The primarily promising scientific results of the last 30 years contributed to the fact that near-infrared spectrometry (NIRS) was established in commercial laboratories as an alternative method to wet chemical standard methods.Furthermore, companies developed technical setups using NIRS for on-line applications of liquid organic manures. Thus, NIRS seems to have evolved to a competitive measurement procedure, although parts of this technique still need to be improved to ensure sufficient accuracy, especially in quality management.
KW  - Chemometrics
KW  - Farmyard manures
KW  - Digestates
KW  - Regression models
KW  - VIS-NIR spectra
KW  - MIR
Y1  - 2022
UN  - https://nbn-resolving.org/urn:nbn:de:bsz:959-opus-60820
SN  - 2073-4395
SS  - 2073-4395
U6  - https://doi.org/10.3390/agronomy12020514
DO  - https://doi.org/10.3390/agronomy12020514
VL  - 12
IS  - 2
SP  - 21
S1  - 21
ER  -