Micronutrient Knowledge Base

Continued increases in average soybean [Glycine max (L.) Merr.] yield will depend on decreasing the yield gap, defined as the difference between current and potential yield, which is the yield of a cultivar grown with the best technologies without limitations on nutrient and water availability and with biological stresses effectively controlled. Research in annual state yield contest fields can provide critical information about yield potentials and plant response differences between ultra-high and average producing areas. Therefore, the objective of this study was to assess seed concentration differences between high- and average-yield areas across soybean growth stages. During the 2015 growing season, in each of seven regions of the “Grow for the Green” yield contest in Arkansas, one contest-entered, high-yield (HY) area in close proximity to one average-yield (AY) area were plant-sampled at the mid-R5, mid-R6, and harvest maturity (HM) growth stages. Grain yields in AY areas ranged from 40 to 98 bu ac-1 (2688 to 6585 kg ha-1; 13% moisture) and averaged 69 bu ac-1 (4664 kg ha-1), while yields in HY areas ranged from 42 to 109 bu ac-1 (2822 to 7324 kg ha-1) and averaged 82 bu ac-1 (5647 kg ha-1). Among all growth stages and yield areas, seed potassium (K) concentration was greatest (P < 0.05) in HY areas at mid-R5 across regions 1.95% (19.5 g kg-1). Averaged across growth stage, seed boron (B) concentration was greater (P < 0.05) in HY 31.76 ppm (31.76 mg kg-1), while seed carbon (C) concentration was greater (P < 0.05) in AY areas (48.9%; 489 g kg-1) across regions. Averaged across yield area, seed P, Ca, Fe, Mn, Zn, Cu, and B concentrations were at least 9% greater (P < 0.05) at mid-R5, while seed N concentration was greatest (P < 0.05) at HM (5.76%; 57.6 g kg-1) than at the other two growth stages. Results of this study demonstrated differences in seed nutrient concentrations across growth stages between HY and AY areas that can be used by producers to maximize soybean yields in all production scenarios.

Background: Among abiotic stresses, salinity and socidity are the major productivity-limiting factors for cultivated crop plants. In two seasons (2022 and 2023), two field-level experimental attempts were made to study the impacts of urea–phosphate (UP) and magnesium oxide nanoparticles (MgNPs) and their combination on the nutritional status, physiological attributes, and yields of Glycine max (L) plants growing under saline-sodic conditions. At 30, 45, and 60 days, UP was applied to the soil at rates of 85.0, 107.0, 127.0, and 150.0 kg ha-1, corresponding to UP1, UP2, UP3, and UP4, respectively, as well as MgONPs via foliar application at doses of 0.0, 50.0, and 100.0 mg L-1, corresponding to MgONP0, MgONP1, and MgONP2, respectively. This study was conducted in a split-plot structure according to a randomized compete block design with three replicates. Results Our results showed that UP3 and UP4 had the strongest effects on most of the measured traits. Both application rates produced the maximum growth–physiological attribute values, except for the leaf dry matter percentage and leaf nutrient levels in both seasons and the leaf iron and zinc contents in the first season (the highest values in these characteristics were achieved in the untreated plants). In addition, the UP4-fertilized plants produced the highest 100-seed weight (HSW), total seed yield (TSY), and seed manganese contents in the two growing seasons. The highest seed oil contents in both seasons, as well as the highest seed phosphorus, calcium, and copper contents in 2023, were recorded in the UP3-treated plants. Regarding MgONPs, our results revealed the significant superiority of the MgONP-treated plants in terms of all the aforementioned growth–physiological parameters and leaf macro- and micronutrient contents, irrespective of the applied dose, except for the LMnCs in 2022 and 2023. The integrative application revealed the clearly superior influence of applying UP3 or UP 4 with MgONP 2 and MgONP 3 on most studied traits. Specifically, for TSY, Model 3 in the 2022 season (adjusted R22 = 0.931) and Model 2 in LPC, LA, and LCaC as the most influential attributes in 2022, and LNC and LKC in 2023. For seed oil content (SOC), Model 3 in 2022 (adjusted R22 = 0.344) and Model 2 in 2023 (adjusted R22 = 0.278) were selected, with SPAD readings and LMnC in 2022, and LMnC and HSW in 2023 as key predictors. Conclusions The use of high rates of a highly soluble and acidic-impact fertilizer, such as UP supplemented with magnesium oxide nanoparticles, may be recommended in saline environments. Keywords Phosphorus fertilizer, Magnesium oxide nanoparticles, Salt-affected soils, Leaves’ nutrient contents, Soybean plant

In the current literature, the impact of nano-particles (NPs) on growth of higher plants has scantly been reported. An investigation was carried out to study the effect of zinc oxide nano-particles (<100 nm) on growth of maize (Zea mays L.) plant, as one of the major agricultural crops, in a solution culture system. Various concentrations of zinc (Zn) were applied through nano-zinc oxide (ZnO) particles (<100 nm) in suspension form and in ionic form through zinc sulfate (ZnSO4) salt in Hoagland solution culture. Experimental results showed that nano zinc oxide particles could enhance and maintain the growth of maize plant as well as conventional Zn fertilizer (as ZnSO4). The plant parameters like plant height, root length, root volume, and dry matter weight were all improved due to application of zinc oxide nano-particle. These findings indicate that plant roots might have the unique mechanism of assimilating nano-Zn and using for its growth and development. Different enzymatic activities were also studied and experimental results revealed that nano-ZnO particles (<100 nm) also governed the enzymatic activity of maize plant. A separate laboratory experiment was also carried out to characterize the zinc oxide nano particle for its size, zeta potential, etc. Keywords: maize (Zea mays L.), nano-ZnO, enzymes, growth, NRA, proline

Intensive cropping systems characterized by continuous cultivation and high nutrient uptake can significantly alter micronutrient dynamics. Boron (B) is particularly affected due to its narrow optimal range, high mobility in soil and sensitivity to changes in pH, organic matter, and moisture condition. This study addresses the need to understand boron transformations under various cropping systems for sustainable soil fertility management. The study was conducted in Gurdaspur district, Punjab on Typic Haplustalfs across seven cropping systems: rice-wheat, maize-wheat, sugarcane-sugarcane, mango, litchi, cole crops, and barren lands. Soil was sampled at five depths (0–15 cm to 90–120 cm) and analyzed for boron fractions using a modified sequential extraction method. Residual boron was the most prevalent fraction, accounting (80–87%) of total boron in all cropping systems. Soils under cole crop recorded the highest concentrations of labile B fractions and total B, due to regular farmyard manure application, while barren lands showed the lowest B levels due to minimal organic inputs. Available boron showed a strong positive association with soil organic carbon (r = 0.82), and a negative relationship but significant with soil pH (r = -0.76), reflecting the combined effect of organic matter and soil chemistry on B availability. These findings underscore the critical role of cropping intensity and organic amendments in shaping boron dynamics in soil. To support soil fertility and long-term agricultural sustainability, the study recommends site-specific boron management strategies, including regular soil testing and balanced use of organic and inorganic B sources, particularly in intensively managed cropping systems. Keywords Boron fractionation · Cropping systems · Soil depth · Typic haplustalfs · Soil depth

When crop fields appear variable, one question commonly asked is whether this is due to a nutrient problem. An excellent tool that can be used to answer this question is plant analysis or tissue testing. For corn, soybean, wheat, and other crops, there are two primary ways plant analysis can be used: as a routine monitoring tool to ensure nutrient levels are adequate in the plant in normal or good looking crops, and as a diagnostic tool to help explain some of the variability and problems we see in soybean growth and appearance in fields.