Impact of Soil-Applied Humic Ameliorative Amendment on the Ligno-Cellulose Quality and Calorific Value of Switchgrass Panicum virgatum L.

Abstract

The main objective of the paper was to determine the ligno-cellulose quality and calorific value of switchgrass Panicum virgatum L. The impact of nutrition treatments (pre-sowing soil humic amendment HA and/or NPK, with annual dose of N on both the treatments, and untreated control UC) and years were evaluated as main effects within a pilot experiment with seven cultivars tested during 2018–2022. Two data sets of acid detergent fiber (ADF), acid detergent lignin (ADL), crude cellulose (CE), hemicellulose (HEM), neutral detergent fiber (NDF), and high heating value (HHV) were evaluated, the primary one in terms of quality content and the secondary one in terms of quality yield. The average ADF content of the switchgrass was 43.94% (range 30.15–50.91), while the average contents of ADL, CE, HEM, NDF, and HHV were 9.21% (6.02–12.41), 34.73% (17.98–40.08), 30.49% (21.34–38.41), 74.43% (59.20–81.15%), and 17.206 kJ g−1 (16.579–17.799), respectively. An adequate value of ADF yield was 4.17 Mg ha−1 (0.01–29.31), while for ADL, CE, HEM, NDF and HHV this was 0.79 Mg ha−1 (0.00–5.39), 3.37 Mg ha−1 (0.01–23.92), 2.79 Mg ha−1 (0.01–17.66), 6.96 Mg ha−1 (0.01–46.93), and 1.466 hGJ ha−1 (0.003–10.603), respectively. In terms of the both quality sets the cultivar was confirmed to be the most important factor followed by the year, with nutrition having the least impact. This impact order of the main effects was valid for each of the parameters. Moreover, in terms of quality yield the formation of homogeneity groups corresponded with dry matter yield and therefore with the order of cultivars (EG 1101 ˃ BO Master ˃ EG 1102 ˃ Kanlow ˃ Alamo ˃ Carthage ˃ NJ Ecotype), the years (2021 ˃ 2020 ˃ 2022 ˃ 2019 ˃ 2018), and the treatments (HA ˃ NPK ˃ UC).

Humic Acid Promotes the Growth of Switchgrass under Salt Stress by Improving Photosynthetic Function

“…Saidimoradi et al also found that HA mitigated the reduction in relative water content, membrane stability index, chlorophyll content, total biomass, and yield of strawberry to resist salt stress [24]. However, as a pasture plant with certain salt tolerance, previous studies have confirmed that HA promotes the germination, rooting and lignocellulose quality of switchgrass [25,26]. The response of physiological and biochemical indexes of switchgrass such as photosynthetic metabolism and plant growth to HA under salt stress remain unclear.…”

Humic Substances: Importance for Agriculture, Affinity and Interactions with Soil Amendments and Pollutants

“…The quality parameters of acid detergent fiber, acid detergent lignin, crude cellulose, hemicellulose, neutral detergent fiber, and high heating values were evaluated. The results indicated that the cultivar, followed by the year and the nutrition, had the greatest effects on the quality factors studied [18].…”