Litterbag-NIRS to Forecast Yield: a Horticultural Case with Biofertilizer Effectors

Abstract

The Litterbag-NIRS method demonstrates and studies the microbial biodiversity of soil in an indirect way, observing the quality decay of ground hay, under real field conditions. Three experiments pertaining to a complex microbial consortium inoculated into six horticultural species used litterbags buried for 60 days. The litter was examined, by an SCiO™ smart-NIR spectrometer, to extract information on the type of transformation that had taken place. Chemometric analyses of single spectra were conducted to compare any variability in three experiments. The partial least squares method was used and cross-validated to associate the observed equivalent yield indexes (YI) to the NIR spectra averaged over each productive plot, in each trial, as well as in the pooled dataset. The cross-validated R 2 values of the three experiments ranged around 0.66, and the inaccuracy of the estimates fluctuated at around ± 5%. The pooled calibration (R 2 = 0.55) showed the presence of outlier treatments, and a marked spectral correlation (R 2 = 0.77) with the 1031 and 986 nm wavelengths. In parallel, a complex of 22 NIRS-predicted variables related to chemical decay of the hay-litter, soil characteristics, and soil microbiology was obtained and partially associated to the YI and to microbial inoculation effects. The Hay-Litterbag-NIRS method can be considered useful to indirectly demonstrate that microbial fertility is an integral part of soil fertility, as evidenced by the significant correlations and predictions of the crop yields, and by the unraveling of the tangle of plant-soil relationships.

Evaluation of Feed Near-Infrared Reflectance Spectra as Predictors of Methane Emissions from Ruminants

“…Although NIRS has been used extensively to predict methane production in biogas production [ 42 ] and in rumen batch culture fermentation [ 28 ], to the best of our knowledge this is the first time to have calibrations between feed NIR spectra and CH 4 yields measured from animal experiments. The calibrations could be improved by using alternative algorithms [ 43 ] and combining other techniques, such as terahertz time-domain spectroscopy [ 44 ], in addition to the expansion of the database.…”

Effects of Multi-Species Microbial Inoculants on Early Wheat Growth and Litterbag Microbial Activity

“…To assess the soil microbial activity indirectly, the Litterbag-NIRS (LBN) method [27,36] was applied. At sowing, one hay litterbag was buried at the edge of each pot at a depth of approximately 10 cm.…”

“…Despite considerable advances in the exploration of the soil microbiome, rapid and cost-effective methods for the evaluation of soil microbiota and their activity are still lacking [28]. The litterbag-NIRS method is a relatively new approach for the indirect characterization and tracing of MC as biofertilizer in terms of soil and litter (degradation) microbial activity [27]. However, it must be assumed that the bio-variability of litterbags is not equal to that of soil [36].…”

“…In parallel, an indirect method for the evaluation of the soil microbial activity and dynamics was applied. The litterbag-NIRS method [27] is based exclusively on the allometry of the decay of a standard litter evaluated by NIR vibrational spectroscopy after sixty days of burial near living crops. From the NIR spectra, by means of chemometric models, it is possible to estimate a series of chemical-bromatological compounds and properties of the litter that reflect the microbial degradation.…”

“…From the NIR spectra, by means of chemometric models, it is possible to estimate a series of chemical-bromatological compounds and properties of the litter that reflect the microbial degradation. In particular, the action of microbial fertilizer has been highlighted, but it has also been repeatedly demonstrated that the method has a predictive capacity with regard to the fertility of the soil in relation to the yields obtained from different crops [27][28][29][30].…”