Soil enzymes are key to predicting nutrient availability and forest fertility.
We aimed to evaluate the influence of forest type on the kinetic and thermodynamic characteristics of soil enzymes.
Soils were sampled at 0–10 and 10–20 cm depth from two pure forests (Pinus tabulaeformis [PTF] and Quercus acutissima [QAF]) and a mixed forest of PTF and QAF (MF) on the Chinese Loess Plateau. Kinetic parameters (maximum enzyme activity [Vmax], half-saturation constant [Km], and enzyme efficiency [Kcat]) and thermodynamic parameters (temperature coefficient [Q10] and activation energy [Ea]) of β-1,4-glucosidase (BG), β-1,4-N-acetylglucosaminidase (NAG), l-leucine aminopeptidase (LAP), and alkaline phosphatase (AP) were determined.
Forest type exerted significant influence on soil enzyme kinetic parameters. The Vmax and Kcat values of BG, NAG, and AP in PTF of 0–10 cm soil depth were 42.54% and 59.22%, 77.18% and 23.08%, and 62.82% and 58.21% higher than that in MF, respectively. The Vmax of AP and Kcat of NAG in PTF of 10–20 cm depth were 34.61% and 39.90% higher than that in MF. The soil enzyme thermodynamic parameters were significantly influenced by forest type and soil depth. At 0–10 cm depth, low values of Q10–Vmax and Q10–Km of BG, Q10–Vmax and Q10–Kcat of NAG, and Ea of BG and NAG were found in PTF. At 10–20 cm depth, low values of Q10–Vmax, Q10–Kcat, and Ea of BG and NAG were found in MF.
PTF was more effective in promoting soil enzymatic reactions, especially in surface soil. MF improved subsoil enzyme thermal stability and reduced temperature sensitivity. The study showed that pure and mixed forests affect soil enzyme characteristics differently, with soil depth as a key factor.
Drought stress (DS) impedes plant growth and development by impairing the uptake of nutrients, such as magnesium, which is central to many physiological processes, particularly photosynthesis. Leaf application was proposed to be an effective strategy to compensate for inadequate Mg2+ supply from the nutrient solution.
The present study is designed to investigate the role of Mg2+ leaf application in ameliorating leaf anatomy and chloroplast ultrastructure changes in faba beans grown under DS.
Hydroponically grown plants were subjected to DS under various levels of Mg2+, that is, sufficient (0.5 mM), deficient (0 mM), and leaf-application (250 mM). Light and transmission electron microscopy (TEM) were conducted to examine leaf anatomy and ultrastructural changes.
Mg2+ deficiency alone and under DS significantly affected plant biomass and photosynthesis. Additionally, sucrose concentration, oxidative stress, and lipid peroxidation were increased. Accordingly, the excessive deposition of photoassimilates in source organs due to the inhibition of phloem loading results in a disruption of the thylakoid structures leading to chloroplast damage. In the current study leaf application of Mg2+ partially ameliorated physiological functions, most notably chlorophyll concentration, photosynthesis and transpiration rate, plant biomass, and preservation of ultrastructure of the chloroplast.
Although the Mg application via roots enhanced drought tolerance, compared to Mg2+ leaf application. However, Mg2+ leaf application was proven to be an efficient strategy in mitigating DS in field trials. Therefore, Mg2+ foliar application should be prioritized for further investigation under relevant environmental stress conditions.
The direct effect of winter cover crops (WCCs) or living mulches (LMs) on a first vegetable crop has already been investigated. However, little is known about the effect on growth and yield of a second cash crop in the rotation.
The aim of the study was to assess the carry-over effect of legumes grown as WCC or LM on winter wheat as a second crop after cabbage, measured in yield and nitrogen release.
Two field trials were carried out in Germany between 2019 and 2022. In the WCC trial, rye, rye with vetch, vetch, pea, and faba bean were used as WCC and compared to bare soil. The WCC biomass was incorporated before cabbage planting in late spring. For the LM trial, perennial ryegrass or white clover was used as LM during cabbage cultivation and compared to bare soil. The LM biomass was incorporated with the cabbage residues and compared to an early incorporation of LM biomass before cabbage planting. In both trials, winter wheat was sown in the fall as the second following main crop in the rotation.
Leguminous WCC species had significant higher wheat yield compared to non-legumes but not compared to the control without WCC. Late incorporation of LM biomass resulted in increased wheat yield at 10.1–10.4 Mg ha−1 compared to an early incorporation before cabbage planting at 9.35 Mg ha−1. Net N releases show that for WCC, the main effect of legume nitrogen fixation is achieved in the first crop cabbage immediately after incorporation of WCC biomass. In the case of leguminous LM, the effects of legume nitrogen fixation are of much higher relevance in the second main crop, winter wheat, due to LM biomass incorporation after cabbage cultivation.
Therefore, we suggest to consider not only the direct but also the carry-over effects of leguminous cover cropping in vegetable crop rotations.
Wheat is a key cereal crop that is substantial to global food security. Fertilizers are crucial in wheat production and significantly impact the yield. This review aims to evaluate the effectiveness of inorganic, organic, and integrated fertilizers in terms of sustainable wheat production and economic and environmental benefits. For this review, we thoroughly examined 133 previous research findings. The results indicate that inorganic fertilizers play a vital role in improving wheat yield. However, continuous use of inorganic fertilizers pollutes the environment, affects beneficial microorganisms in the soil, and increases the emissions of greenhouse gases, consequently decreasing crop yield. Organic fertilizers enhance soil quality, which is critical for crop growth and development. However, a high concentration of methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2) are emitted from organic fertilizers, but the CO2 emission rate is less than the sequestration rate. Integrated fertilizers trade off the drawbacks of both inorganic and organic fertilizers. Integrated fertilizers decrease nitrous oxide (N2O) and ammonia (NH3) emissions and carbon loss by 11%–24%, 13%–27%, and 18%, respectively, compared to the sole use of fertilizers. From the review analysis, the highest grain yield (4855 kg ha−1) and net benefit ($2836.66) are achieved by using a combination of 75% organic and 25% inorganic fertilizers at a rate of 120 kg N ha−1. Therefore, this combination is recommended for the users. Furthermore, a site-specific approach research is needed on integrated fertilizers that simultaneously focus on economic and environmental profits. Also, there must be a policy that supports the farmers in teaching, training, and subsidizing them to adopt integrated fertilizers for sustainable wheat production and improving food security.
Composts made from food waste will soon become more widespread on the market thanks to the upcoming enforcement of the legal obligation to sort biowaste. Our experiment aims at improving knowledge on the short-term effects of these composts on soils’ physicochemical properties and vegetable crops.
Three composts with contrasting characteristics were tested: a 100% v/v green waste compost (C1), and two composts composed of 50% v/v food waste and 50% v/v green waste, one prepared directly on the soil (C2) and the other from a competing producer who have the French NFU 44-051 (AFNOR NF U 44-051, 2006) certification for an organic amendment (C3). They were applied at a rate of 100 t ha−1 (dry matter) on two cropped soils with contrasting textures. Soil-and-compost mixes and compost-free soil were planted with lettuce, radish, and potato.
Seventy-four days after planting, composts improved some soil physicochemical properties. The compost-amended soils had better saturated hydraulic conductivity (Ks, 1 10−3–2.5 10−3 cm s−1) than the compost-free soil (0.5 10−3 cm s−1), and water-stable aggregates were higher than the initial value in C3 soil, equal to it in C2 soil, and lower in C1 soil. pH, total nitrogen, and organic carbon increased in all compost-amended soils. Food waste compost stimulated crop production. The yields (dry matter) of all three crops were two to three times higher in the two soils amended with food waste compost compared to unamended soil, whereas they decreased almost two times in the soil amended with green waste compost due to nitrogen immobilization. Trace metals (particularly Pb and Cd) added by the composts, although present in edible parts of the plants, did not exceed the European rules for trace metals.
Thus, food waste composts have positive effects on soils and vegetable crops, and the higher their organic matter content, the higher these positive effects.
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