Chemical evaluation of partially acidulated phosphate rocks and their impact on dry matter yield and phosphorus uptake of maize.

Previous studies investigated the direct application of phosphate rock and its partially acidulated to enhance its solubility compared to soluble fertilizers. However, the interaction between the effect of particles diameter and partial acidulation of phosphate rock on phosphorus (P) availability and its effect on dry matter yield and P uptake is still elusive. This study was conducted to assess the effect of partially acidulated Egyptian phosphate rocks with different particle size diameters on P availability and its effect on dry matter yield and P uptake of maize (Zea mays L.). A pot experiment was conducted on maize plants grown on light clay soil for 42 days. Acidulation was done by mixing phosphate rock with single superphosphate or triple superphosphate at a total rate of 200 mg P kg-1 with five acidulation mix ratios (100:0, 75:25, 50:50, 25:75, and 0:100). Different particle size diameters of phosphate rocks (500, 212, 75, and <45 µm included nano-particles ranged from 69.3 to 25.7 nm) were used. We found that dry matter yield and P uptake increased significantly due to the use of partially acidulated phosphate rocks especially when triple superphosphate was used for acidulation and the mixing ratio of 50:50 was the best. We also found that maize yield and P uptake increased significantly with decreasing particle size. It is recommended to use finely grounded partially acidulated phosphate rocks with particles diameter less than 45 µm at acidulation ratio 50% and no need to increase acidulation ratio above that as a slow-release phosphate fertilizer.

Global patterns of soil gross immobilization of ammonium and nitrate in terrestrial ecosystems.

Microbial nitrogen (N) immobilization, which typically results in soil N retention but based on the balance of gross N immobilization over gross N production, affects the fate of the anthropogenic reactive N. However, global patterns and drivers of soil gross immobilization of ammonium (INH4 ) and nitrate (INO3 ) are still only tentatively known. Here, we provide a comprehensive analysis considering gross N production rates, soil properties, and climate and their interactions for a deeper understanding of the patterns and drivers of INH4 and INO3 . By compiling and analyzing 1966 observations from 274 15 N-labelled studies, we found a global average of INH4 and INO3 of 7.41 ± 0.72 and 2.03 ± 0.30 mg N kg-1  day-1 with a ratio of INO3 to INH4 (INO3 :INH4 ) of 0.79 ± 0.11. Soil INH4 and INO3 increased with increasing soil gross N mineralization (GNM) and nitrification (GN), microbial biomass, organic carbon, and total N and decreasing soil bulk density. Our analysis revealed that GNM and GN were the main stimulators for INH4 and INO3 , respectively. The structural equation modeling showed that higher soil microbial biomass, total N, pH, and precipitation stimulate INH4 and INO3 through enhancing GNM and GN. However, higher temperature and soil bulk density suppress INH4 and INO3 by reducing microbial biomass and total N. Soil INH4 varied with terrestrial ecosystems, being greater in grasslands and forests, which have higher rates of GNM, than in croplands. The highest INO3 :INH4 was observed in croplands, which had higher rates of GN. The global average of GN to INH4 was 2.86 ± 0.31, manifesting a high potential risk of N loss. We highlight that anthropogenic activities that influence soil properties and gross N production rates likely interact with future climate changes and land uses to affect soil N immobilization and, eventually, the fate of the anthropogenic reactive N.

Vital roles of sustainable nano-fertilizers in improving plant quality and quantity-an updated review.

Nanotechnology has received much attention because of its distinctive properties and many applications in various fields. Nanotechnology is a new approach to increase agricultural production with premium quality, environmental safety, biological support, and financial stability. Ecofriendly technology is becoming progressively important in modern agricultural applications as alternatives to traditional fertilizers and pesticides. Nanotechnology offers an alternative solution to overcome the disadvantages of conventional agriculture. Therefore, recent developments in using nanoparticles (NPs) in agriculture should be studied. This review presented a novel overview about the biosynthesis of NPs, using NPs as nano-fertilizers and nano-pesticides, the applications of NPs in agriculture, and their role in enhancing the function of biofactors. We also, show recent studies on NPs-plant interactions, the fate and safety of nanomaterials in plants, and NPs' function in alleviating the adverse effects of abiotic stress and heavy metal toxicity. Nano-fertilizers are essential to reduce the use of inorganic fertilizers and reduce their antagonistic effects on the environment. Nano-fertilizers are more reactive, can penetrate the epidermis allowing for gradual release, and targeted distribution, and thus reducing nutrients surplus, enhancing nutrient use efficiency. We also, concluded that NPs are crucial in alleviating abiotic stress and heavy metal toxicity. However, some studies reported the toxic effects of NPs on higher plants by induction of oxidative stress signals via depositing NPs on the cell surface and in organelles. The knowledge in our review article is critical in defining limitations and future perspectives of using nano-fertilizers as an alternative to conventional fertilizers.