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- Nutrient Cycling in Agroecosystemson December 15, 2024 at 12:00 am
- Comparing carbon nanomaterial and biochar as soil amendment in field: influences on soil biochemical properties in coarse-textured soilson December 15, 2024 at 12:00 am
Abstract With rising food demand, sandy soils are increasingly used in agriculture. Carbon nanomaterials (CNMs) are a potential soil amendment that can enhance soil fertility and health in sandy soils, but most studies have been conducted in controlled greenhouse or laboratory environments. Therefore, there is limited information on the effect of CNMs on soil biochemical properties at the field scale, particularly in comparison with alternative carbon sources (e.g., biochar). We conducted field trials with sugar beet (Beta vulgaris) and field corn (Zea mays) using different application rates of novel water-dispersible CNMs (pH:5.5, zeta-potential: − 40.6 mV, primary particle diameter: 30-60 nm) applied at various rates (100–1200 mg kg−1), and compared CNMs to biochar applied at one rate (1%) along with unfertilized and fertilized controls. We evaluated the comparative effects of CNMs and biochar on soil chemical (pH, EC, N, P, K, C) and biological (respiration, microbial biomass carbon, soil urease, phosphatase and dehydrogenase enzymes) properties at 30DAS (days after sowing), 65/70DAS and after harvest. Biochar significantly raised soil pH while both C amendments reduced soil EC, particularly in soils that weren’t limed. Among fertilized treatments, soil nutrient availability during crop growth was enhanced to a greater extent with CNMs than with biochar, with significant increases in KCl-extractable NO3−-N and NH4+-N (37–54%), along with P (45–94%; post-harvest samples) and K (18-256%) extractable with Mehlich 3. Soil biological activity with CNMs and the fertilized control was similar at low to medium CNM application rates, but high CNMs doses significantly reduced soil microbial respiration and the activity of urease and dehydrogenase enzymes. Pearson correlations and a principal component analysis highlighted that soil nutrient availability and microbial activity were closely correlated for both crops. Overall, we found that CNMs added at the low-medium application rates (100–400 mg kg−1) was superior to biochar (1%) in improving soil chemical and biochemical properties in sandy soils, providing an additional amendment for the management of marginal lands.
- Integrating organic fertilizers in maize-mung bean intercropping: implications for soil carbon dynamics and greenhouse gas reductionon December 13, 2024 at 12:00 am
Abstract Organic fertilizers have great potential to improve crop production while reducing greenhouse gas (GHG) emissions in agroecosystems. To study their effect on GHG emissions, a field experiment over a two-year period (2021 and 2022) was carried out to quantify carbon dioxide (CO2) and nitrous oxide (N2O) emissions. Experimental treatments included: (i) two types of organic fertilizers [wheat residue (WR) and sheep manure (SM)]; and (ii) three cropping systems [monocropping of maize (Zea mays L., Ma) and mung bean (Vigna radiata (L.) R. Wilczek, Mu), and their intercropping (Ma + Mu)]. Total crop biomass and its carbon (C) and nitrogen (N) content, soil CO2 and N2O emissions, soil temperature and moisture were measured. The results showed that Ma + Mu_WR significantly reduced cumulative CO2 emissions by 36% and 28% compared to the Ma_WR and Mu_WR, respectively. Similarly, Ma + Mu_SM reduced soil CO2 emissions by 38% and 70% compared to Ma_SM and Mu_SM, respectively. In addition, Ma + Mu_WR had 69% and 71% lower cumulative N2O emissions than Ma_WR and Mu_WR, respectively, while Ma + Mu_SM showed 48% and 55% lower emissions than Ma_SM and Mu_SM, respectively. WR application significantly increased C input and the C input/output. In the Mu, WR fertilizer led to a significant reduction in both C output and total C emitted, whereas in Ma + Mu, these parameters were not affected by the type of organic fertilizers. In Ma, C output was higher under WR than SM, but total C emitted remained unaffected. This study suggests that integrating organic fertilizer into an intercropping system provides a sustainable and environmentally friendly approach to effective GHG mitigation.
- Nitrogen fertilizer classification using multivariate fingerprinting with stable isotopeson December 1, 2024 at 12:00 am
Abstract The steadily growing demand for fertilizers and increasing interest for organic inputs result in rapid expansion and diversification of the solid nitrogen (N) fertilizer market. Fertilizer legislations distinct different fertilizers classes (i.e. organic, organo-mineral, inorganic), but standards and norms related to nutrient- and carbon origin remain dynamic and lag behind. This, together with poor analytical understanding of commercially available N sources leaves many open questions to industries and farmers, fostering increased prevalence of fertilizer adulteration and false claims on the organic fertilizer market. This work presents a thorough, science-based multivariate assessment on a wide sample set (n = 52) of the solid N fertilizer market, including multiple state-of-the-art analytical attributes, such as stable isotopes of nitrogen and carbon. Results present the possibility to correctly (94%) classify N fertilizers using multivariate fingerprinting with linear discriminant analysis. We extract analytical cut-off values for discriminants indicative for ingredient origin and conclude that, when a fertilizer has (i) a bulk δ15N below 2‰; and (ii) a relatively high total N content (> 15%), from which (iii) a high share (> 50%) is water soluble (i.e. in ammonium or nitrate form), it is extremely unlikely to be of pure biologic origin. We also present additional analyses (e.g. amino acids, peptide sequences, δ13C of specific compounds, and stable isotopes of boron) that can then be used to further trace down the N sources in novel fertilizer products. This work contributes to future debates, regulations, and further development of analytical standards for solid N fertilizers, possibly to be used in fraud detection. Graphical abstract
- Fertilization strategies to reduce yield-scaled N2O emissions based on the use of biochar and biochar-based fertilizerson December 1, 2024 at 12:00 am
Abstract Novel fertilization strategies, such as the use of biochar-based fertilizers (BBFs) and the co-application of biochar with mineral fertilizers, have shown promising results for mitigating nitrous oxide (N2O) emissions and reducing N losses in agroecosystems. Two greenhouse experiments were performed with radish to evaluate: (1) the mitigation of yield-scaled N2O emissions using BBFs, produced at either 400 or 800 °C and enriched with urea, compared to the co-application of raw biochars with urea; and (2) the N2O mitigation potential of low rates of raw biochars, equivalent to those used with BBFs fertilization, co-applied with low and high N rates (90 and 180 kg N ha−1). BBF produced at 800 °C reduced yield-scaled N2O emissions by 32% as compared to the urea treatment, and by 60%, as compared to the combination of raw biochar with urea. This reduction was attributed to the slow rate of N release in BBF. On the contrary, the co-application of low rates of biochar with urea increased yield-scaled N2O emissions as compared to the fertilization with urea alone. Low rates of biochar (1.4–3.1 t ha−1) reduced yield-scaled N2O emissions only with a high rate of N fertilization. High-pyrolysis-temperature biochar, co-applied with synthetic fertilizer, or used to produce BBFs, demonstrated lower yield-scaled N2O emissions than biochar produced at a lower pyrolysis temperature. This study showed that BBFs are a promising fertilization strategy as compared to the co-application of biochar with synthetic fertilizers.