Inorganic Nitrogen Application Research Articles

Overexpression of rice OsNRT1.1A/OsNPF6.3 enhanced the nitrogen use efficiency of wheat under low nitrogen conditions.

Overexpression of OsNRT1.1A promotes early heading and increases the tolerance in wheat under nitrogen deficiency conditions. The application of inorganic nitrogen (N) fertilizers is a major driving force for crop yield improvement. However, the overuse of fertilizers significantly raises production costs and leads to environmental problems, making it critical to enhance crop nitrogen use efficiency (NUE) for the sake of sustainable agriculture. In this study, we created a series of transgenic wheat lines carrying the rice OsNRT1.1A gene, which encodes a nitrate transporter, to investigate its possible application in improving NUE in wheat. The transgenic wheat exhibited traits such as early maturation that were highly consistent with the overexpression of OsNRT1.1A in Arabidopsis and rice. However, we also observed that overexpression of the OsNRT1.1A gene in wheat can facilitate the growth of roots under low N conditions but has no effect on other aspects of growth and development under normal N conditions. Thus, it may lead to the improvement of wheat low N tolerance,which is different from the effects reported in other plants. A field trial analysis showed that transgenic wheat exhibited increased grain yield per plant under low N conditions. Moreover, transcriptome analysis indicated that OsNRT1.1A increased the expression levels of N uptake and utilization genes in wheat, thereby promoting plant growth under low N conditions. Taken together, our results indicated that OsNRT1.1A plays an important role in improving NUE in wheat with low N availability.

Combined Application of Organic and Inorganic Nitrogen and Seed Inoculation with Rhizobacteria (Stenotrophomonas maltophilia FA-9) Improved Productivity, Nitrogen Use Efficiency, and Economic Returns of Pearl Millet

Nitrogen (N) availability and soil microbiota exert significant impacts on plant metabolic systems and yield. Different studies have indicated that yield and nitrogen use efficiency (NUE) of pearl millet (Pennisetum glaucum L.R.Br.) can be improved by the inoculation of N-fixing bacteria. However, the interactive effects of different N sources and bacteria inoculation on growth, productivity, and NUE of pearl millet have been less explored. Therefore, individual and interactive effects of different N sources (organic and inorganic) and bacteria inoculation on growth, productivity, and NUE of pearl millet were investigated in this study. Two different N sources, i.e., organic (farmyard manure) and inorganic (urea) alone or in 50% + 50% combinations (urea + FYM), were used to supply the recommended amount of N. Similarly, seeds were inoculated with two different N-fixing bacteria, i.e., endobacteria (Enterobacter sp. MN17) and rhizobacteria (Stenotrophomonas maltophilia FA-9). Urea + farmyard manure (FYM) and seed inoculation rhizobacteria improved soil attributes, yield-related traits, grain quality, NUE, and net economic returns. Soil porosity was significantly improved by seed inoculation with both bacteria and FYM application. Similarly, seed inoculation with rhizobacteria increased soil organic carbon by 45.45% and 34.88% during the 1st and 2nd year of the study, respectively. Urea + FYM application combined with rhizobacteria seed inoculation improved the number of grains per ear (23.49 and 23.63%), 1000-grain weight (5.76% and 7.85%), grain yield (23.19% and 25.0%), and NUE (33.83 and 48.15%). Similarly, grain quality was significantly improved by seed inoculation with both bacteria. Likewise, urea + FYM combined with rhizobacteria improved nitrogen use efficiency (NUE) by 33.83% and 48.15% in 2020 and 2021, respectively, compared to no N application and no seed inoculation. The highest economic returns (1506.4 and 1506.9 USD) were noted for urea + FYM application combined with rhizobacteria seed inoculation. Therefore, urea + FYM application combined with rhizobacteria (S. maltophilia FA-9) seed inoculation seemed a viable approach to improve grain yield, grain quality, NUE, and net economic returns of pearl millet.

Biochar enhancement of nitrification processes varies with soil conditions

Application of inorganic nitrogen (N) fertilizers in agriculture can increase emissions of nitrous oxide, a potent greenhouse gas, leaching of nitrate (NO3−), a groundwater contaminant hazardous to human health, and soil acidification. Soil amendment with biochar potentially mitigates these losses and undesirable outcomes. However, there have been considerable inconsistencies in reported impacts, likely owing to variable physiochemical characteristics of the biochar materials and/or the soil environment. This study methodically evaluated the impact of biochar soil incorporation on N transformation and underlying microbial processes using soils with varying biochar types, soil texture, soil moisture, and manure compost co- amendments. Laboratory incubations were conducted to monitor the fate of urea fertilizer N spiked in biochar amended and unamended soils by assaying soil ammonium (NH4+), nitrite (NO2−), and NO3− concentrations, pH, and abundances of soil nitrifiers; ammonia oxidizing bacteria and archaea (AOB and AOA) and Nitrospira with the capacity to perform complete ammonia oxidation (comammox). Soil moisture was a critical factor affecting N transformation processes, more so than biochar, but biochar did result in significantly different concentrations of N species in response to urea application. Biochar enhanced nitrification, more significantly in drier conditions and in sandy soil. Biochar offered some buffering potential in the neutral-alkaline, unsaturated soils, preventing >1 unit drop in pH compared to unamended soils. Co-application of biochar with manure composts enhanced nitrification slightly, which was evidenced by higher abundances of some soil nitrifiers at 4 weeks, although increases in nitrification rates were not statistically significant. Soil nitrifier populations tended to increase in response to a pinewood biochar, but trends differed for saturated soil, in soils of differing textures, or when different biochar materials were evaluated. Thus, when evaluating implications of biochar on the fate of mineral N fertilizer, soil moisture and other environment conditions should be considered.

Effects of Long-Term Organic–Inorganic Nitrogen Application on Maize Yield and Nitrogen-Containing Gas Emission

A sustainable model of combined organic–inorganic fertilizer application for high maize yields and environmental health is important for food security. The short-term combined application of organic and inorganic fertilizers can improve crop yields; however, the effect of different proportions of organic and inorganic fertilizers on the maize yield and nitrogen gas emissions in a long time series has not been reported. In this study, field experiments and DeNitrification-DeComposition (DNDC) model simulations were used to study the long-term effects of substituting inorganic fertilizers with organic fertilizers on crop yields and nitrogen-containing gas emissions. Six treatments were included: no nitrogen (CK); urea (U1); and 25%, 50%, 75%, and 100% of the urea N substituted by organic fertilizers (U3O1, U1O1, U1O3, and O1, respectively). The DNDC model was calibrated using the field data from the U1 treatment from 2018 to 2020 and was validated for the other treatments. The results showed that this model could effectively simulate crop yields (e.g., nRMSE < 5%), soil NH3 volatilization, and N2O emissions (nRMSE < 25%). In addition, long-term (26 years) simulation studies found that the U1O1 treatment could considerably increase maize yields and ensure yield stability, which was 15.69–55.31% higher than that of the U1 treatment. The N2O, NH3, and NO emissions were in the descending order of U1 > U3O1 > O1 > U1O3 > U1O1, and the total nitrogen-containing gas emissions from the U1O1 treatment decreased by 53.72% compared with the U1 treatment (26 years). Overall, substituting 50% of inorganic nitrogen with organic nitrogen could maintain the high yield of maize and reduce emissions of nitrogen-containing gases, constituting a good mode for the combined application of organic–inorganic nitrogen in this area.

Hydroponic Common-Bean Performance under Reduced N-Supply Level and Rhizobia Application.

This study aims to explore the possibility of a reduced application of inorganic nitrogen (N) fertiliser on the yield, yield qualities, and biological nitrogen fixation (BNF) of the hydroponic common bean (Phaseolus vulgaris L.), without compromising plant performance, by utilizing the inherent ability of this plant to symbiotically fix N2. Until the flowering stage, plants were supplied with a nutrient solution containing N-concentrations of either a, 100%, conventional standard-practice, 13.8 mM; b, 75% of the standard, 10.35 mM; or c, 50% of the standard, 6.9 mM. During the subsequent reproductive stage, inorganic-N treatments b and c were decreased to 25% of the standard, and the standard (100% level) N-application was not altered. The three different inorganic-N supply treatments were combined with two different rhizobia strains, and a control (no-inoculation) treatment, in a two-factorial experiment. The rhizobia strains applied were either the indigenous strain Rhizobium sophoriradicis PVTN21 or the commercially supplied Rhizobium tropici CIAT 899. Results showed that the 50-25% mineral-N application regime led to significant increases in nodulation, BNF, and fresh-pod yield, compared to the other treatment, with a reduced inorganic-N supply. On the other hand, the 75-25% mineral-N regime applied during the vegetative stage restricted nodulation and BNF, thus incurring significant yield losses. Both rhizobia strains stimulated nodulation and BNF. However, the BNF capacity they facilitated was suppressed as the inorganic-N input increased. In addition, strain PVTN21 was superior to CIAT 899-as 50-25% N-treated plants inoculated with the former showed a yield loss of 11%, compared to the 100%-N-treated plants. In conclusion, N-use efficiency optimises BNF, reduces mineral-N-input dependency, and therefore may reduce any consequential negative environmental consequences of mineral-N over-application.

Multispecies forages in the Australian dairy feedbase: is there a biological business case?

This review considers the potential role of multispecies swards in de-risking Australian dairy systems that currently rely heavily on monocultures of perennial ryegrass and high rates of inorganic nitrogen application to be productive. Recent trends in increasing inorganic nitrogen fertiliser prices, societal pressure for increased environmental sustainability of farming practices, coupled with variable and extreme weather events have renewed interest for functionally diverse pasture mixtures. Evidence from the latest international studies either for or against the purported benefits of multispecies swards (e.g. productive, resilient, and environmentally positive) is examined. There is an ever-growing body of evidence confirming that species richness can promote high levels of productivity at low or zero rates of nitrogen fertiliser application, often with increasingly positive effects as species richness increases. However, results within and between different levels of species richness are not always consistent, suggesting that not all multispecies swards will perform alike, even at a constant level of functional diversity. A multitude of other factors is presented that interact to determine the success of one multispecies sward over another. These include soil type and fertility, species choice, functional group proportions, sward management under either grazing or cutting, fertiliser regimes, and grazing management practices. It was concluded that this complexity gives rise to a need for further research into the biological mechanisms behind multispecies mixtures to determine the factors, other than simply species richness, that will guarantee success as more farmers inevitably search for alternatives to perennial ryegrass pasture in the Australian dairy farming industry.

Effect of Combined Application of Chicken Manure and Inorganic Nitrogen Fertilizer on Yield and Quality of Cherry Tomato

Unreasonable application of inorganic nitrogen (N) fertilizer on cherry tomatoes (Solanum lycopersicum var. cerasiforme) has resulted in serious environmental threats. The advantages of application of organic manure combined with inorganic N fertilizer for vegetable production systems have been reported widely, but there are still few studies on cherry tomato production. Therefore, this study aims to determine the impact of a combined application of organic manure (in form of chicken manure at different application rate of 0 and 40 t ha−1) with inorganic N fertilizer (in form of urea at various N application rates of 0, 160 and 320 kg N ha−1) on the fruit yield and quality of cherry tomato across two seasons. Results showed that inorganic N application exhibited positive effects on fruit yield and its associated components of cherry tomato. However, there was no significant difference in terms of fruit yield and its associated components between the two N rates of inorganic N (160 and 320 kg N ha−1), indicating that fruit yield is not improved significantly when the N application rate exceeds some threshold. Under chicken manure application treatments, however, an increased N rate did not show a positive effect on fruit yield. Importantly, chicken manure application has greatly increased fruit yield and fruit quality (represented by membership function indicator) by 43% and 23%, respectively in comparison with zero manure application. In particular, the soluble protein and titratable acid were increased by 124% and 118%, respectively. Overall, these results suggested that chemical N fertilizers could be largely replaced with chicken manure. Furthermore, the combined application of organic with inorganic N fertilizers seems to be a promising management practice for reducing the reliance on use of inorganic N fertilizer, while mitigating the environmental burden for cherry tomato production.

Macroaggregation is promoted more effectively by organic than inorganic fertilizers in farmland ecosystems of China—A meta-analysis

Fertilizers can affect formation, size distribution and stability of soil aggregates in agricultural ecosystems. Although many independent studies have been recently carried out to understand the effects of fertilizers on soil aggregates in farmland ecosystems of China, the results remain widely contradictory. A meta-analysis was conducted using a total number of 1286 observations from 100 publications between 2005 and 2020 to quantitatively analyze the effects of different fertilizer treatments, duration of fertilizer application, regional heterogeneity, soil texture, and aeration conditions on the composition of soil aggregates. Results showed that long-term annual single application of organic fertilizer, inorganic fertilizer (N and NPK) and combined application of organic and inorganic fertilizers increased the proportion of > 2 mm fractions, but decreased the proportion of 0.25–0.053 mm and < 0.053 mm fractions, respectively. The promotion of macroaggregates (> 0.25 mm) by long-term application of organic fertilizer and the combined application of organic and inorganic fertilizers were significantly stronger than inorganic fertilizer, but the opposite for microaggregate (< 0.25 mm). The application of organic and inorganic fertilizer and straw return should be applied in sandy loam and silty loam, and clay loam was applied mainly manure (M), nitrogen plus manure (NM), nitrogen, phosphorus and potassium plus manure (NPKM) and nitrogen, phosphorus and potassium plus straw return (NPKS), while reducing the single application of inorganic nitrogen (N). Inorganic fertilizers and combined with organic-inorganic fertilizer increased the proportion of > 2 mm fractions in anaerobic soil significantly more than that in well-aerated soil. Long-term annual single application of N and M promoted the proportion of > 2 mm and 2–0.25 mm fractions significantly more than that of combined application of nitrogen and phosphorus and potassium (NPK), NM, NPKM and NPKS in experiments conducted in the Northeast of China. In addition, our results also showed that the proportion of macroaggregates did not increase linearly with continuous fertilizer input, but with the extension of fertilization durations, the macroaggregates transformed to microaggregates gradually after reaching the saturation state. Organic fertilizer and organic-inorganic combined application had longer time to promote macroaggregates than inorganic fertilizer.

Genome sequencing and genetic analysis of recombinant inbred lines reveals important agronomic traits related loci under different nitrogen fertilization.

The intensive application of inorganic nitrogen has contributed to increasing the crop yield with the risk of environmental damage. High nitrogen fertilizer requirements are a long-standing problem in japonica cultivation. In the present study, 200 recombinant inbred lines derived from two representative japonica varieties of Japanese and Chinese varieties, Akitakomachi and Liaogeng5, respectively, were planted under different nitrogen fertilization conditions. The relationships among nitrogen fertilization, genetic background, and important agronomic traits were surveyed through the phenotypic investigation and next-generation sequencing. The results showed that the yield components of Akitakomachi dramatically decreased along with the nitrogen reduction, whereas those of Liaogeng5 exhibited a slight decrease. The appearance quality and milling quality of both Akitakomachi and Liaogeng5 were improved, especially Liaogeng5. The recombinant inbred lines (RILs) showed similar trends to their parental lines. The QTLs analysis of important agronomic traits detected 17 loci, one QTL clustering located on chromosome 9 that corresponded to the plant height, panicle angle, grain number per panicle, harvest index, and taste value was identified to be synonymous with a previously reported gene, DEP1. The function of DEP1 was verified by a knock-out mutant constructed by CRISPR/Cas9. The dep1 mutant exhibited improved grain quality without severe yield penalty under nitrogen reduction conditions. The results of the present study provide useful information for the improvement of food security by enhancing nitrogen use efficiency.

Influence of Nitrogen Sources Applied by Fertigation to an Enriched Soil with Organic Compost on Growth, Mineral Nutrition, and Phytochemicals Content of Coriander (Coriandrum sativum L.) in Two Successive Harvests.

The aim of the present study was to evaluate the effects of nitrogen source applied by fertigation to an enriched soil with organic compost on plant growth, mineral nutrition, and phytochemical contents in two successive harvests in coriander. The treatments were as follows: unfertilized soil, soil enriched with organic compost, and soil enriched with organic compost to which 60 kg N ha−1 as ammonium nitrate and as ammonium sulfate applied by fertigation were added. Ammonium nitrate addition allowed to obtain a high total fresh yield (3.6 kg m−2) with a low inorganic nitrogen input. Ammonium nitrate increased plant shoot dry weight; fresh yield; and shoot N, K, and Ca uptake in the first harvest. Ammonium nitrate relative to organic compost and to ammonium sulfate increased fresh yield by approximately 57 and 25%, respectively. However, ammonium sulfate in the first harvest greatly increased shoot total phenols, from 137 mgGAE/100 g FW in ammonium nitrate to 280.4 mgGAE/100 g FW. Coriander’s fresh yield, in the second harvest, was unaffected by nitrogen addition. However, ammonium nitrate increased shoot total phenols and FRAP activity. Overall, the shoot phytochemical accumulation in the second harvest was lower than in the first. The combined application of ammonium nitrate and organic compost is a strategy to reduce inorganic nitrogen application.

Available Nutrient Status of Soil as Influenced by Combined Application of Humic Acid and Inorganic Nitrogen

A field experiment was carried out to study the influence of different levels of humic acid (10, 20, 30 kg ha-1) and inorganic N fertilizer viz., 100 % of recommended dose and 75 % of recommended dose on chemical properties of soil under direct sown rice at Agricultural college farm, Bapatla during 2019. The experiment was laid out in RBD with ten treatments replicated thrice with BPT-5204 variety of rice as test crop. Soil samples collected at tillering, panicle initiation and harvest stages of crop were analyzed for chemical properties like available N, P2O5, K2O, Sulphur and cationic micro-nutrients (Fe, Mn, Zn, Cu). Results indicated that increased availability of N, P2O5, K2O, Sulphur and cationic micro-nutrients (Fe, Mn, Zn, Cu) were observed with the treatment T6 involving 100% RDN and HA @ 30 kg ha-1.

Effects of Combination of Organic and Inorganic Nitrogen on Nitrification and Denitrification in Two Salinized Soils

Focusing on typical mildly saline soil, S1 (EC, 0.62 dS·m-1), and moderately saline soil, S2 (EC, 1.17 dS·m-1), in Hetao Irrigation District of Inner Mongolia, the response of nitrification and denitrification process to salinization degree and the proportion of organic and inorganic nitrogen application were studied. The experimental treatments consisted of(1) no nitrogen(CK), (2) only inorganic nitrogen(U1), and(3) organic nitrogen(U3O1, U1O1, U1O3, and O1) compared to 25%, 50%, 75%, and 100% inorganic nitrogen. The results showed that increasing salinity reduced the soil nitrification potential and increased the soil denitrification capacity. The soil nitrification potential of the S1 soil was 28.81%-69.67% higher than that of the S2 soil, while the denitrification capacity was reduced by 17.16%-88.91%. With an increase in salinity, the AOB abundance and nitrification contribution rate were reduced, but the AOA abundance and nitrification contribution rate were increased. Furthermore, an increase in salinity increased the abundance of nirK and nirS bacteria, and increased N2O/(N2O+N2) production, but reduced the abundance of nosZ. In the S1 soil, the nitrification potential and denitrification capacity of U1O1 were highest, increasing by as much as 18.59% and 15.87%, respectively, compared to the U1 treatment. In the S2 soil, the difference in the soil nitrification potential between the various fertilization treatments was not significant, and the denitrification capacity of the O1 treatment was highest. The S1 and S2 saline soils treated with U1O1 and O1, respectively, had higher AOB gene abundance and nitrification contribution rates, increased nirS and nosZ gene abundances, and significantly reduced N2O/(N2O+N2) product ratios. Our findings suggested that mildly saline soils(120 kg·hm-2 urea+120 kg·hm-2 organic fertilizer) and moderately saline soils(240 kg·hm-2 organic fertilizer) are more conducive to soil nitrification and denitrification processes compared to soils to which inorganic nitrogen is applied alone.

Effects of complementary and sole applications of inorganic fertilizers and winery solid waste compost on maize yield and soil health indices

The development of plant nutrition systems that enhance soil productivity through the use of mineral fertilizers combined with organic fertilizers has recently gained increased attention. Two field experiments were conducted in 2018 (from February to June) and 2018/19 (from December 2018 to April 2019) to assess the effects of complementary application of inorganic nitrogen (N) and phosphorus (P) fertilizers (INPF) and winery solid waste (WSW) composts on maize yield and soil health indicators. The INPF and optimum rates of microbially inoculated and uninoculated WSW compost types were combined at different ratios (0:0, 75:25, 50:50, 25:75 and 0:100 w/w) to supply proportionate N and P amount. The recommended INPF rates for maize (200 kg N ha-1 and 90 kg P ha-1) were mixed and included as a standard control. The interaction of compost type and application rate had no significant effects on total biomass yield (TBY), grain yield (GY) and harvest index (HI). The compost type had significant effects on GY and HI in 2018/19. The TBYs obtained from the 50:50, 75:25 and 100:0 compost-INPF combinations were significantly higher than that recorded from untreated control across the compost types in 2018. The 25:75 and 50:50 compost-INPF combinations gave GYs which were significantly higher than that obtained from the untreated control in 2018/19. In many instances, soil pH and the contents of organic C, NO3, P, K, Na and Zn recorded from treatments with the different mix ratios of compost and INPF were higher than that recorded from the untreated control. Grain yield correlated significantly and positively with the contents of soil NH4 (r = 0.59) and P (r = 0.53) indicating that these nutrients contributed to the final GY. In conclusion, the joint application of compost and INPF at 25:75 and 50:50 ratios appears promising for improving GY. Increase in soil K content suggested the need for a controlled application of WSW compost followed by frequent soil testing exercise to monitor and avoid unnecessary K build-up that may induce the deficiencies of other plant nutrients.

Long‐term inorganic nitrogen application changes the ammonia‐oxidizing archaeal community composition in paddy soils

AbstractThe abundance and taxonomic composition of ammonia‐oxidizing archaea (AOA) were assessed in paddy soils that had received more than 50 years of fertilization with and without inorganic N. The inorganic N fertilized treatments were: NPK and NPK + CO (nitrogen (N), phosphorus (P), potassium (K) and compost (CO)). The treatments without inorganic N were: CO, PK and control (unfertilized soils). Quantitative PCR (qPCR) analysis of the archaeal amoA gene showed no significant changes in AOA abundance following the long‐term application of inorganic N fertilizers. However, subsequent analysis of amoA gene sequencing data showed that inorganic N application significantly changed the AOA community composition and alpha diversity indices. Edge principal components analysis (PCA) showed varying contributions of distinct AOA lineages in separating samples according to the fertilization treatment. Addition of inorganic N favoured an increase in the abundance of AOA lineages belonging to Nitrososphaera, and the treatments without inorganic N additions formed a separate cluster dominated by Nitrosotalea lineage. The distinct response of the two AOA lineages points towards different community organization of soil AOA and strongly supports the concept of habitat partitioning in paddy soil ecosystems.Highlights Lineages of AOA responded differently to different N management practices. Long‐term N fertilization selectively enriched AOA lineages, with C:N ratio a factor associated with such changes Inorganic N favoured Nitrososphaera lineage abundance Regardless of fertilizer status, Nitrosotalea lineage was dominant in the absence of inorganic N fertilization.

Genomic basis of geographical adaptation to soil nitrogen in rice.

The intensive application of inorganic nitrogen underlies marked increases in crop production, but imposes detrimental effects on ecosystems1,2: it is therefore crucial for future sustainable agriculture to improve the nitrogen-use efficiency of crop plants. Here we report the genetic basis of nitrogen-use efficiency associated with adaptation to local soils in rice (Oryza sativa L.). Using a panel of diverse rice germplasm collected from different ecogeographical regions, we performed a genome-wide association study on the tillering response to nitrogen-the trait that is most closely correlated with nitrogen-use efficiency in rice-and identified OsTCP19 as a modulator of this tillering response through its transcriptional response to nitrogen and its targeting to the tiller-promoting gene DWARF AND LOW-TILLERING (DLT)3,4. A 29-bp insertion and/or deletion in the OsTCP19 promoter confers a differential transcriptional response and variation in the tillering response to nitrogen among rice varieties. The allele of OsTCP19 associated with a high tillering response to nitrogen is prevalent in wild rice populations, but has largely been lost in modern cultivars: this loss correlates with increased local soil nitrogen content, which suggests that it might have contributed to geographical adaptation in rice. Introgression of the allele associated with a high tillering response into modern rice cultivars boosts grain yield and nitrogen-use efficiency under low or moderate levels of nitrogen, which demonstrates substantial potential for rice breeding and the amelioration of negative environment effects by reducing the application of nitrogen to crops.

Effect of organic compost and inorganic nitrogen fertigation on spinach growth, phytochemical accumulation and antioxidant activity

The aim of this study was to evaluate the effect of the addition of organic compost in combination with the inorganic nitrogen fertigation on growth, phytochemical accumulation, and antioxidant activity of spinach (Spinacia oleracea L. cv. Manatee). Soil blocked spinach seedlings (six seedlings per block), three blocks per pot (316 plants m−2) were transplanted after 18 days after emergence into to 12 L pots. The treatments were: unfertilized soil, organic compost, organic compost +75 kg of N ha−1, applied as ammonium sulfate; and organic compost +75 kg N ha-1, applied as ammonium nitrate. The addition of organic compost to unfertilized soil increased the fresh yield. The application of inorganic N from the two sources in relation to organic compost treatment increased spinach fresh yield from 2.3 to 4.81 kg m−2 and shoot dry weight from 0.60 to 1,31 g plant−1. Levels of carotenoids also increased with inorganic N addition, producing higher values in plants grown with organic compost + ammonium nitrate (31.14 mg/100 g fresh weight). However, the addition of N led to a decrease in leaf-blade total phenols from 75 to 56 mg gallic acid equivalents/100mg fresh weight. The addition of inorganic N led to a dramatic decrease in leaf-blade ferric reducing antioxidant activity. This effect was higher with ammonium sulfate application. The application of organic compost and inorganic nitrogen had no influence on the petiole's phytochemical accumulation and antioxidant activity.

Biochar amendment mitigates greenhouse gases emission and global warming potential in dairy manure based silage corn in boreal climate

About 11% of the global anthropogenic greenhouse gases (GHGs) emissions result from agricultural practices. Dairy manure (DM) application to soil is regarded as a best management practice due to C sequestration and improvement of soil physiochemical properties. However, GHGs emissions from the soil following the DM application could offset its advantages. Biochar (BC) is known to affect N transformation and GHGs emissions from soil. There had been considerably less focus on the BC amendment and its effects on GHGs emissions following DM application under field conditions. The objectives of this study were; i) to determine the temporal patterns and cumulative GHGs fluxes following DM and inorganic nitrogen (IN) application and, ii) to investigate BC amendment impact on DMY, GWP, direct N2O emission factor (EFd) and the response of CH4 emissions (RC) in DM based silage corn. To achieve these objectives a two-year field experiment was conducted with these treatments: 1) DM with high N conc. (DM1: 0.37% N); 2) DM with low N conc. (DM2: 0.13% N); 3) IN; 4) DM1+BC; 5) DM2+BC; 6) IN + BC; and 7) Control (N0); and were laid out in randomized complete block design with four replications. BC amendment to DM1, DM2 and IN significantly reduced cumulative CO2 emission by 16, 25.5 and 26.5%, CH4 emission by 184, 200 and 293% and N2O emission by 95, 86 and 93% respectively. It also reduced area-scaled and yield-scaled GWP, EFd, RC and enhanced DMY. Thus, BC application showed great potential to offset the negative effects of DM application i.e GHGs emissions from the silage corn cropping system. Further research is needed to evaluate soil organic carbon and nitrogen dynamics (substrates for GHG emissions) after DM and BC application on various soil types and cropping systems under field conditions.

Nitrogen use efficiency and performance of maize (Zea mays L.) cultivars as influenced by calcium carbide and inorganic nitrogen application rates in a derived savanna

Field experiments were conducted to investigate nitrogen use efficiency and performance of maize (Zea mays L.) cultivars as influenced by calcium carbide (CaC2) and nitrogen (N) rates in a derived Savanna (2016 and 2017). Maize cultivars {SUWAN-I [open pollinated variety (OPV)] and OBA SUPER II (hybrid)}, rates of N (0, 60 and 90 kg ha−1) and CaC2 (0, 30 and 60 kg ha−1), were arranged in split-split plot respectively, fitted into a randomized complete block design in three replicates. N Partial factor productivity (PFPN), Agronomic Use Efficiency (both years) and Apparent recovery of N (2017) increased in the order 60 > 90 > 0 kg N ha−1, except N Internal use efficiency which was in the order 0 > 60 > 90 kg N ha−1 (2017). Grain yield increased with increasing rates of N in both years. OBA SUPER-II had significantly higher grain yield than SUWAN-I (2017). Similar pattern was observed on number of grains per cob, dry cob weight, PFPN and plant height (2017). Conversely in 2016, grain, total and shoot N uptakes were significantly higher in SUWAN-I than OBA SUPER-II. Increasing application of CaC2 increased grain N uptake and number of grains per cob. Number of leaves and stem girth increased in the order of 60 > 0 > 30 kg CaC2 ha−1. Increased grain yield with N rates could be associated with NHI and N use efficiency. These evidences suggested that hybrid maize performed better than OPV in a derived Savanna.

Manure application increased denitrifying gene abundance in a drip-irrigated cotton field.

Application of inorganic nitrogen (N) fertilizer and manure can increase nitrous oxide (N2O) emissions. We tested the hypothesis that increased N2O flux from soils amended with manure reflects a change in bacterial community structure and, specifically, an increase in the number of denitrifiers. To test this hypothesis, a field experiment was conducted in a drip-irrigated cotton field in an arid region of northwestern China. Treatments included plots that were not amended (Control), and plots amended with urea (Urea), animal manure (Manure) and a 50/50 mix of urea and manure (U+M). Manure was broadcast-incorporated into the soil before seeding while urea was split-applied with drip irrigation (fertigation) over the growing season. The addition treatments did not, as assessed by nextgen sequencing of PCR-amplicons generated from rRNA genes in soil, affect the alpha diversity of bacterial communities but did change the beta diversity. Compared to the Control, the addition of manure (U+M and Manure) significantly increased the abundance of genes associated with nitrate reduction (narG) and denitrfication (nirK and nosZ). Manure addition (U+M and Manure) did not affect the nitrifying enzyme activity (NEA) of soil but resulted in 39–59 times greater denitrifying enzyme activity (DEA). In contrast, urea application had no impact on the abundances of nitrifier and denitrifier genes, DEA and NEA; likely due to a limitation of C availability. DEA was highly correlated (r = 0.70–0.84, P < 0.01) with the abundance of genes narG, nirK and nosZ. An increase in the abundance of these functional genes was further correlated with soil NO3−, dissolved organic carbon, total C, and total N concentrations, and soil C:N ratio. These results demonstrated a positive relationship between the abundances of denitrifying functional genes (narG, nirK and nosZ) and denitrification potential, suggesting that manure application increased N2O emission by increasing denitrification and the population of bacteria that mediated that process.

Effect of long-term application of mineral fertilizers and FYM on microbial dynamics, yield and quality of FCV tobacco (Nicotiana tabacum) grown in vertisols

A long term manurial experiment (Permanent Manurial Trial) with the objective to study the effect of continuous application of organic manure (FYM) and inorganic fertilizers (NPK) on microbial diversity, yield and quality of Flue-cured Virginia (FCV) tobacco (Nicotiana tabacum L. ) as monocrop was carried out at CTRI Farm, Katheru, for 53 years commencing from 1956-57 to 2008-09. The results obtained before the closing of the experiment (2003- 2008) are discussed in this paper. The microbial dynamics expressed in terms of culturable microbial populations, i.e. bacteria, fungi, actinomycetes, Azotobacter and PSB were measured after 53 years of continuous application of mineral fertilizers and organic amendments to vertisols. The population of bacteria, actinomycetes, Azotobacter and PSB were maximum in plots treated with mineral fertilizers and FYM while fungal population was maximum in mineral fertilizers treated plots. The population of bacteria, actinomycetes, Azotobacter and PSB increased in the treatments with the addition of P and K fertilizers alone or in combination. The fungal population decreased with the addition of NPK along with the FYM. Bacillus, Pseudomonas species of bacteria and Trichoderma, Aspergillus and Rhizopus species of fungi, Streptomyces species of actinomycetes were the main dominating culturable microorganisms in all the treatments. The FYM amended plots sustained crop productivity and microbial populations at higher levels than rest of the mineral fertilizer treatments. The average cured leaf yields indicated that only farm yard manure and inorganic nitrogen application has exerted pressure in increasing the cured leaf yields by 24. 52% and 26. 97% respectively in VT-1158 variety of tobacco in vertisols. The nitrogenous fertilizers alone had the most deleterious effect on crop productivity and the biological soil environment. The results of the present study support the concept of balanced fertilization and integrated nutrient management practices for improving the soil quality and sustained crop productivity.