Responses of soil enzymatic activities and microbial biomass phosphorus to improve nutrient accumulation abilities in leguminous species.

Fertilizers application are widely used to get a higher yield in agricultural fields. Nutrient management can be improved by cultivating leguminous species in order to obtain a better understanding of the mechanisms that increase the amount of available phosphorus (P) and potassium (K) through fertilizer treatments. A pot experiment was conducted to identify the leguminous species (i.e., chickpea and pea) under various fertilizer treatments. Experimental design is as follows: T0 (control: no fertilizer was applied), T1: P applied at the level of (90 kg ha-1), T2: (K applied at the level of 90 kg ha-1), and T3: (PK applied both at 90 kg ha-1). All fertilizer treatments significantly (p < 0.05) improved the nutrient accumulation abilities and enzymes activities. The T3 treatment showed highest N uptake in chickpea was 37.0%, compared to T0. While T3 developed greater N uptake in pea by 151.4% than the control. However, T3 treatment also increased microbial biomass phosphorus in both species i.e., 95.7% and 81.5% in chickpeas and peas, respectively, compared to T0 treatment. In chickpeas, T1 treatment stimulated NAGase activities by 52.4%, and T2 developed URase activities by 50.1% higher than control. In contrast, T3 treatment enhanced both BGase and Phase enzyme activities, i.e., 55.8% and 33.9%, respectively, compared to the T0 treatment. Only the T3 treatment improved the activities of enzymes in the pea species (i.e., BGase was 149.7%, URase was 111.9%, Phase was 81.1%, and NAGase was 70.0%) compared to the control. Therefore, adding combined P and K fertilizer applications to the soil can increase the activity of enzymes in both legume species, and changes in microbial biomass P and soil nutrient availability make it easier for plants to uptake the nutrients.

Liming potential and characteristics of biochar produced from woody and non-woody biomass at different pyrolysis temperatures.

Large amount of wastes are burnt or left to decompose on site or at landfills where they cause air pollution and nutrient leaching to groundwater. Waste management strategies that return these food wastes to agricultural soils recover the carbon and nutrients that would otherwise have been lost, enrich soils and improve crop productivity. The incorporation of liming materials can neutralize the protons released, hence reducing soil acidity and its adverse impacts to the soil environment, food security, and human health. Biochar derived from organic residues is becoming a source of carbon input to soil and provides multifunctional values. Biochar can be alkaline in nature, with the level of alkalinity dependent upon the feedstock and processing conditions. This study conducted a characterization of biochar derived from the pyrolysis process of eggplant and Acacia nilotica bark at temperatures of 300 °C and 600 °C. An analysis was conducted on the biochar kinds to determine their pH, phosphorus (P), as well as other elemental composition. The proximate analysis was conducted by the ASTM standard 1762-84, while the surface morphological features were measured using a scanning electron microscope. The biochar derived from Acacia nilotica bark exhibited a greater yield and higher level of fixed carbon while possessing a lower content of ash and volatile components compared to biochar derived from eggplant. The eggplant biochar exhibits a higher liming ability at 600 °C compared to the acacia nilotica bark-derived biochar. The calcium carbonate equivalent, pH, potassium (K), and phosphorus (P) levels in eggplant biochars increased as the pyrolysis temperature increased. The results suggest that biochar derived from eggplant could be a beneficial resource for storing carbon in the soil, as well as for addressing soil acidity and enhancing nutrients availability, particularly potassium and phosphorus in acidic soils.

Nutrient Uptake Potential of Nonleguminous Species and Its Interaction with Soil Characteristics and Enzyme Activities in the Agro-ecosystem.

The potential nutrient uptake abilities of a plant are essential for improving the yield and quality. Green manures can take up a huge amount of macronutrients from the soil. The mechanisms underlying the differences in nutrient uptake capacity among different nonlegume species remain unclear. The plot experiments were conducted to investigate the performance of nonlegume species including forage radish (Raphanus raphanistrum subsp. sativus), oil radish (Raphanus sativus var. Longipinnatus), February orchid (Orychophragmus violaceus L), and rapeseed (Baricca napus), while a ryegrass (Lolium perenne L.) species was used as a control. The study results showed that forage radish had the highest nutrient uptake (N and P), i.e., 322 and 101% in Hunan and 277 and 469% in the Sichuan site, respectively, compared with the control. While the greatest K uptake was found in forage radish, i.e., 123%, and February orchid, 243%, in the Hunan and Sichuan sites. Forage radish also presented higher phosphorus use efficiency in both experimental areas: Hunan by 301% and Sichuan by 633% compared to the control. Significant modifications were found in nutrient availability and enzyme activities after the cultivation of various species. The oil radish enhanced the ß-glucosidase (BG) and leucine-aminopeptidase enzyme activities by 324 and 367%, respectively, while forage radish developed the highest phosphatase (Phase) and N-acetyl-glucosaminidase (NAG) activities compared to the ryegrass in Hunan. In the Sichuan site, the oil radish promotes enzyme activities such as Phase (126%), BG (19%), and NAG (17%), compared to the control. It is concluded that forage radish, oil radish, and February orchid can easily improve soil nutrient quality in green manuring practices and provide valuable nutrient management systems.

The Global Dilemma of Soil Legacy Phosphorus and Its Improvement Strategies under Recent Changes in Agro-Ecosystem Sustainability.

Phosphorus (P) is one of the six key elements in plant nutrition and effectively plays a vital role in all major metabolic activities. It is an essential nutrient for plants linked to human food production. Although abundantly present in both organic and inorganic forms in soil, more than 40% of cultivated soils are commonly deficient in P concentration. Then, the P inadequacy is a challenge to a sustainable farming system to improve the food production for an increasing population. It is expected that the whole world population will rise to 9 billion by 2050 and, therefore, it is necessary at the same time for agricultural strategies broadly to expand food production up to 80% to 90% by handling the global dilemma which has affected the environment by climatic changes. Furthermore, the phosphate rock annually produced about 5 million metric tons of phosphate fertilizers per year. About 9.5 Mt of phosphorus enters human food through crops and animals such as milk, egg, meat, and fish and is then utilized, and 3.5 Mt P is physically consumed by the human population. Various new techniques and current agricultural practices are said to be improving P-deficient environments, which might help meet the food requirements of an increasing population. However, 4.4% and 3.4% of the dry biomass of wheat and chickpea, respectively, were increased under intercropping practices, which was higher than that in the monocropping system. A wide range of studies showed that green manure crops, especially legumes, improve the soil-available P content of the soil. It is noted that inoculation of arbuscular mycorrhizal fungi could decrease the recommended phosphate fertilizer rate nearly 80%. Agricultural management techniques to improve soil legacy P use by crops include maintaining soil pH by liming, crop rotation, intercropping, planting cover crops, and the consumption of modern fertilizers, in addition to the use of more efficient crop varieties and inoculation with P-solubilizing microorganisms. Therefore, exploring the residual phosphorus in the soil is imperative to reduce the demand for industrial fertilizers while promoting long-term sustainability on a global scale.