Soil sample storage conditions affect measurements of pH, potassium, and nitrogen

AbstractSoil quality monitoring schemes are a useful tool for assessing the potential of soils to perform desired services such as agricultural productivity. When researchers or other stakeholders wish to compare results between different schemes or studies, failure to consider differences in soil sample storage conditions presents a significant potential for error. Here, we compared levels of nitrogen and potassium, as well as pH, in agricultural soil samples stored under three different conditions (refrigerated, frozen, and oven‐dried). All tests were performed after 7 and 24 weeks of storage. Nitrate decreased significantly in dried (p < 0.001) samples. When refrigerated, nitrate first increased (p < 0.01) and then decreased (p < 0.001). Nitrate levels where unchanged at Week 7 in the freezer but decreased significantly at Week 24 (p < 0.001). Nitrite and ammonium increased after drying (p < 0.001) and when frozen (p < 0.001 and p < 0.05) but remained stable when refrigerated. There was no significant difference in potassium levels between the fresh control and Week 7 in the freezer, but potassium had increased at Week 24 (p < 0.05). Potassium concentration increased in refrigerated samples (p < 0.001) and fluctuated up and down in dried samples (p < 0.01). pH measurements fluctuated significantly in refrigerated and frozen samples (p < 0.001 and p < 0.01, respectively) but were unchanged in dried samples. We suggest that soil monitoring schemes standardize their sample storage, and we encourage researchers to clearly report soil sample storage conditions in publications, to improve transparency and reproducibility

Constraints using the liquid fraction from roadside grass as a bio‐based fertilizer

Background: Roadside grass cuttings are currently considered a waste product due to their association with road sweepings as contaminated waste, therefore, their potential as a biofertilizer is understudied. Aim: This study aimed to determine whether grass liquid fraction (GLF) collected from a roadside verge in Maldegem, Belgium, and pressed using a screw press was suitable as a biofertilizer. Methods: The characterization of the heavy metal content of the GLF was conducted using an ICP-OES. From May to September 2019, a pot experiment was set up using a randomized block design to compare tomato plant growth, yield, and nutrition for GLF-treated plants to two commercial fertilizers and tap water as a control. Results: The heavy metal content of the GLF was below the maximum permissible concentrations (MPCs) for organic fertilizers as set out by the European Comission fertilizer regulation 1069/2009 and 1107/2009 (European Comission, 2019). However, despite having a fairly well-balanced nutrient content (0.1% N, 0.04% P2O5, and 0.2% K2O), GLF had a negative effect on the growth, root weight, and yield of the tomato plants, killing six out of ten plants. GLF also promoted mold growth in the soil of some plants. Since the GLF was uncontaminated, heavy metal toxicity did not cause the negative effect. Conclusions: Previous research showed that liquid fractions from some plants negatively affect the growth of others due to allelopathic chemicals; this, together with the stimulation of fungal growth, could have caused the negative effects observed. Future experiments will investigate the herbicidal property of GLF and possible treatments to potentially recover the nutrients contained within the GLF for application as a biofertilizer

Constraints using the liquid fraction from roadside grass as a bio‐based fertilizer

Background: Roadside grass cuttings are currently considered a waste product due to their association with road sweepings as contaminated waste, therefore, their potential as a biofertilizer is understudied.Aim: This study aimed to determine whether grass liquid fraction (GLF) collected from a roadside verge in Maldegem, Belgium, and pressed using a screw press was suitable as a biofertilizer. Methods: The characterization of the heavy metal content of the GLF was conducted using an ICP-OES. From May to September 2019, a pot experiment was set up using a randomized block design to compare tomato plant growth, yield, and nutrition for GLF-treated plants to two commercial fertilizers and tap water as a control. Results: The heavy metal content of the GLF was below the maximum permissible concentrations (MPCs) for organic fertilizers as set out by the European Comission fertilizer regulation 1069/2009 and 1107/2009 (European Comission, 2019). However, despite having a fairly well-balanced nutrient content (0.1% N, 0.04% P2O5, and 0.2% K2O), GLF had a negative effect on the growth, root weight, and yield of the tomato plants, killing six out of ten plants. GLF also promoted mold growth in the soil of some plants. Since the GLF was uncontaminated, heavy metal toxicity did not cause the negative effect. Conclusions: Previous research showed that liquid fractions from some plants negatively affect the growth of others due to allelopathic chemicals; this, together with the stimulation of fungal growth, could have caused the negative effects observed. Future experiments will investigate the herbicidal property of GLF and possible treatments to potentially recover the nutrients contained within the GLF for application as a biofertilizer.Background: Roadside grass cuttings are currently considered a waste product due to their association with road sweepings as contaminated waste, therefore, their potential as a biofertilizer is understudied.Aim: This study aimed to determine whether grass liquid fraction (GLF) collected from a roadside verge in Maldegem, Belgium, and pressed using a screw press was suitable as a biofertilizer. Methods: The characterization of the heavy metal content of the GLF was conducted using an ICP-OES. From May to September 2019, a pot experiment was set up using a randomized block design to compare tomato plant growth, yield, and nutrition for GLF-treated plants to two commercial fertilizers and tap water as a control. Results: The heavy metal content of the GLF was below the maximum permissible concentrations (MPCs) for organic fertilizers as set out by the European Comission fertilizer regulation 1069/2009 and 1107/2009 (European Comission, 2019). However, despite having a fairly well-balanced nutrient content (0.1% N, 0.04% P2O5, and 0.2% K2O), GLF had a negative effect on the growth, root weight, and yield of the tomato plants, killing six out of ten plants. GLF also promoted mold growth in the soil of some plants. Since the GLF was uncontaminated, heavy metal toxicity did not cause the negative effect. Conclusions: Previous research showed that liquid fractions from some plants negatively affect the growth of others due to allelopathic chemicals; this, together with the stimulation of fungal growth, could have caused the negative effects observed. Future experiments will investigate the herbicidal property of GLF and possible treatments to potentially recover the nutrients contained within the GLF for application as a biofertilizer.A