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The aim of this study was to assess the relationships between the soil water-holding capacity (SWHC), nitrate nitrogen (N-NO3−) and extractable potassium (K) content of soil; the vine nutrient content, vigour and yield; and the quality of the musts and wines in DOCa Rioja vineyards over a five-year period (2010–2014). The SWHC, N-NO3− and extractable K content of the soil were analysed in twelve cv. Tempranillo (Vitis vinifera L.) plots. Vine yield, nutritional parameters and the K and polyphenol compounds in the musts and wines were determined. In general, both the SWHC and the soil N-NO3− content were positively correlated with the N and K content of the petiole, the shoot weight and the bunch weight, but negatively correlated with the polyphenol and anthocyanin content of the musts and wines. The K extractable content was also correlated with the K content of the petiole and with the K in the musts and wines. The SWHC, the N-NO3− and the extractable K are soil parameters which have been linked to the growth and ripening of the vine plant and to the composition of the must and wine. For DOCa Rioja agroclimatic conditions, assessment of these soil parameters would enable selecting soils that support obtaining wines of better quality.

The course of N-NO3- concentrations in soil, N transfer from the catch crops Vicia sativa L. and Trifolium resupinatum L. to the companion grass Lolium multiflorum ssp. gaudinii (Parl.) Schinz et Keller, and the preceding crop effect on Lolium multiflorum ssp. italicum (A. Br.) Volkart were studied in a field experiment. Catch crops were sown in pure stands and grass/legume swards (= two species in alternating rows) at two sowing dates and harvested at different dates from August to November. Vicia sativa was more effective concerning N2 fixation than Trifolium resupinatum, this was also evident from above ground N yield and N-NO3- amount of the soil. The factor sowing date had the greatest influence on N yield. N transfer to the companion grass was generally low. Early sown legumes in pure stands and in mixture temporarily caused slightly increased N-NO3- amounts in soil compared with unfertilized grass in winter and following spring, whereas late sown legumes apparently had no effect on N-NO3- amounts. Both legumes had a considerable preceding crop effect in the mixture and in the pure stand for both sowing dates.

Nitrogen (N) fertilizer is an input that has played an important role in grain yield, N use efficiency (NUE), and agronomic efficiency (AE) that needs to be studied on rainfed wheat grown in permanent beds as a planting system. The objective of this study was to test the effect of N treatments on yield, NUE and AE from 2005 to 2009. The experimental design consisted of three N rates (25, 50 and 75 kg/ha) and four N timing treatments (two single basal applications and two splits), plus a control plot (0 N). Results showed that N rate and N timing treatments had no effect on grain yield, but years, meanwhile Year–N rate interaction affected NUE and AE. Precipitation and post-harvest soil N-NO3 were identified as factors to test the years' effect on yield, NUE and AE. Regression procedures showed that the effect was greater for 25 kg N/ha treatment. The relationships between these variables and precipitation were positive, whereas the opposite occurred with soil N-NO3. NUE and AE, however, showed negative values in crop seasons with moisture constraints from precipitation (<335 mm) and soil N-NO3 (>90 kg N-NO3/ha). This result indicated that N removal and yield in these years were larger in control plots (0 N) than fertilizer application. Precipitation and soil N-NO3, rather than N treatments, explained most of the yield, NUE and AE variation over years. Therefore, to enhance that effect of weather and soil, further research on alternate N sources is needed. [ABSTRACT FROM AUTHOR]

The central temperate Argentinean region is currently affected by rising water tables, allowing higher and more stable maize yields (Zea mays L) when they fluctuate within optimum depth. However, limited information was available for optimizing N management in these environments. Yield response to N rates was explored in soils with influencing groundwater (always <3.5 m depth), and different environment and management variables were examined to help explain differential yield responses across sites. A total of 15 rainfed experiments (site × year combinations) were conducted with five N rates (0–240 kg N ha−1) tested at two different timings (sowing and V7) in a factorial design. A consistent yield response to N rate was evident, increasing yields from 2,300 to 6,900 kg ha−1 across sites. Yields at maximum N levels ranged from 13,700 to 16,900 kg ha−1. Fertilization timing had a minor and inconsistent effect on yield across sites. At a maize grain/fertilizer N price ratio of 10, the economically optimal N rate ranged from 117 to 206 kg N ha−1. Soil N‐NO3 at sowing, previous crop, and apparent–indigenous N supply (INS) helped explain differential yield responses across sites, and response models for obtaining economic optimum rates considering the influence of these variables are provided. These results highlight the relevance of N rate, rather than timing, as a critical crop management decision in environments with high water availability and yield. [ABSTRACT FROM AUTHOR]

Optimizing fertilizer rates is a common problem in modern agriculture. Frequently used response models ignore basic statistical assumptions and do not allow quantifying the effects of variables influencing yield response to fertilizer, generating uncertainty in fertilizer rate recommendations. We used linear mixed-effects models to explore maize (Zea mays L.) yield response to applied nitrogen (N) in late sowings, and we tested different predictors for explaining yield responses across sites. Data included yield response trials to applied N at 17 different environments (combination site × year) with four to five N rates replicated twice in each trial. The best model (Model A) that included significant effect of N rate applied, sowing date, and soil N-NO3 at sowing described grain yield variations with high accuracy (R2 = 0.93). Another best model (Model B) showed that soil type as additional variable affected significantly yield response to applied N. The final model indicated that the overall response across sites was characterized by a linear coefficient of 67 kg grain ha-1 per additional kg N ha-1 applied and a quadratic coefficient of -0.37 kg grain ha-1 per additional kg N ha-1 applied. Across all sites, soil N-NO3 at sowing (explored range from 34 to 356 kg N ha-1) explained 46% of the variability in the linear yield response to applied N. We proposed a method and generated statistical models with site specific covariates that can help optimize farmers' decisions on the use of optimal N fertilizer rates. [ABSTRACT FROM AUTHOR]

High nitrogen (N) fertiliser rates are usually applied to increase agricultural yields, leading to high nitrous oxide (N2O) emissions. This is a greenhouse gas that contributes to climate change and depletes the ozone layer. This study aimed to optimise N use efficiency and quantify N2O emission factors (EF1) by measuring the effect of N rates on the yield of a potato-cover crop rotation, apparent N use efficiency (NUE) and N2O emissions. The two-year experiment was carried out on volcanic soils (1.6% carbon, 1.4% N) in southern Chile (40°52′ S, 73°03′ W). Three N application rates were evaluated (80, 150 and 300 kg N ha−1), 35% of which was applied at the planting stage (granular) and 65% at the tubering stage. A control treatment with no N addition was also included. Reducing N fertilisation to 80 kg N ha−1 increased NUE by three times, reduced N2O-N emissions by 33% and reduced emission intensity by 27% without a detrimental impact on crop yield and marketable tuber calibre. No significant difference (p < 0.05) was observed in the N2O emission factor (EF1) because of a low rainfall year. The results suggest that in rainfed agriculture systems, N fertiliser application can be significantly reduced without sacrificing potato yield, favouring the economic and environmental sustainability of potato production. [ABSTRACT FROM AUTHOR]

Diversifying crop rotations by incorporating legumes is recommended to enhance the resilience of agricultural systems against environmental stresses and optimize nitrogen utilization. Nonetheless, ploughing forage legumes or grass-legumes poses a significant risk of nitrate leaching. The study aimed to assess the impact of strip tillage intercropping management on soil mineral nitrogen, water-extractable organic carbon, mobile humic substances content, and winter wheat (Triticum aestivum L.) grain yield compared to forage legume and winter wheat monocropping with conventional tillage. In the intercropping systems, the following bicrops were used: black medick (Medicago lupulina L.) with winter wheat, white clover (Trifolium repens L.) with winter wheat, and Egyptian clover (Trifolium alexandrinum L.) with winter wheat. Research was conducted in two experiments. The results indicated that after implementing strip tillage and winter wheat intercropping, the soil mineral nitrogen content was similar to or lower than that observed in conventional tillage and winter wheat sowing after forage legumes. Winter wheat grain yield in intercrops decreased compared to the legumes monocultures that were ploughed before winter wheat sowing. The highest amount of water- extractable organic carbon was in intercropping growing white clover and winter wheat bicrops or in all fields (except Egyptian clover and winter wheat bicrops) after applying strip tillage. During the research period, the quantities of mobile humic substances and mobile humic acids exhibited similar changes. Their content increased substantially in fields with white clover and Egyptian clover, regardless of whether the legumes were ploughed or grown with winter wheat. [ABSTRACT FROM AUTHOR]

Copyright of Acta Scientiarum: Agronomy is the property of Universidade Estadual de Maringa and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In savanna ecosystems, the seasonal effects of nitrogen forms and availability, as well as their utilization by plants, influence the abundance and distribution of herbaceous species in grassland communities. This study examines seasonal effects on nitrogen availability and utilization by native grass species in the Cerrado, a savanna ecosystem in Brazil. Ammonium and nitrate levels in soil, nitrate acquisition and transport, and Nitrate Reductase Activity (NRA) in different plant parts during dry and wet periods were assessed. Results indicated higher soil nitrate availability during the wet period, influenced by precipitation, with leaves showing a higher nitrate content compared to roots. There was seasonal modulation in nitrate reduction, with leaves being the primary site during the dry period and roots during the wet period. The studied grass species exhibited heterogeneous responses to seasonal nitrogen availability, potentially affecting community abundance patterns. Findings suggest that edaphoclimatic seasonality plays a crucial role in nitrogen distribution and utilization capacity by grass plants in the Cerrado, contributing to the understanding of these ecosystems' ecology. [ABSTRACT FROM AUTHOR]

Soil properties can affect plant population dynamics and the coexistence of native and invasive plants, thus potentially affecting community structure and invasion trends. However, the different impacts of soil physicochemical properties on species diversity and structure in native and invaded plant communities remain unclear. In this study, we established a total of 30 Alternanthera philoxeroides-invaded plots and 30 control plots in an area at the geographical boundary between North and South China. We compared the differences in species composition between the invaded and native plant communities, and we then used the methods of regression analysis, redundancy analysis (RDA), and canonical correspondence analysis (CCA) to examine the impacts of soil physicochemical properties on four α-diversity indices and the species distribution of these two types of communities. We found that A. philoxeroides invasion increased the difference between the importance values of dominant plant species, and the invasion coverage had a negative relationship with the soil-available potassium (R2 = 0.135; p = 0.046) and Patrick richness index (R2 = 0.322; p < 0.001). In the native communities, the species diversity was determined with soil chemical properties, the Patrick richness index, the Simpson dominance index, and the Shannon–Wiener diversity index, which all decreased with the increase in soil pH value, available potassium, organic matter, and ammonium nitrogen. However, in the invaded communities, the species diversity was determined by soil physical properties; the Pielou evenness index increased with increasing non-capillary porosity but decreased with increasing capillary porosity. The determinants of species distribution in the native communities were soil porosity and nitrate nitrogen, while the determinants in the invaded communities were soil bulk density and available potassium. In addition, compared with the native communities, the clustering degree of species distribution in the invaded communities intensified. Our study indicates that species diversity and distribution have significant heterogeneous responses to soil physicochemical properties between A. philoxeroides-invaded and native plant communities. Thus, we need to intensify the monitoring of soil properties in invaded habitats and conduct biotic replacement strategies based on the heterogeneous responses of native and invaded communities to effectively prevent the biotic homogenization that is caused by plant invasions under environmental changes. [ABSTRACT FROM AUTHOR]

Little attention has been given to the utilization of permanent cover crops in vineyard agroecosystems in semi-arid Mediterranean climatic conditions to increase soil organic carbon or its effects on N availability. We evaluated the effect of permanent cover crops with resident vegetation on labile organic matter fractions and inorganic N availability with respect to conventional tillage in a semi-arid vineyard. The field experiment was conducted on Typic Haploxerept soil, located in La Rioja area (Central River Ebro Valley). Soil samples were collected during June 2009, 5 years after covers crops were established. Soil organic carbon (SOC), water-soluble carbon (WSC), potentially mineralizable nitrogen (PMN), nitrate (N-NO3 −) and ammonium (N-NH4 +) were measured. At soil depths of 0–2.5 and 2.5–5 cm the cover crops increased SOC, WSC and PMN. So the results indicated a soil quality improvement. The cover crop treatment reduced soil N-NO3 − and increased the WSC to inorganic N ratio at 0–45 cm depth. PMN and WSC increments suggest a more active microbial biomass that could promote the immobilization and recycling of N-NO3 −, and therefore might partially explain the reduction in N-NO3 − pools under cover crops. [ABSTRACT FROM AUTHOR]

We characterized and compared the use of nitrate (N-NO3-), in three recognized pioneer and secondary tropical species, analyzing their relationships with the availability of inorganic nitrogen in the soil of a riparian forest. We tested the hypothesis that pioneer species of the ecological succession (Cecropia glaziovi - Cgl) would be more responsive to N-NO3- available and would have high nitrate reductase activity (NRA) in leaves while secondary species (Inga marginata - Ima and Hymenaea courbaril - Hco) would have less responsiveness and would have lower levels of this enzyme on its leaves. We evaluated, tested and compared the NRA and N-NO3- content in leaves and xylem sap of each species. We measured N-NO3- and N-NH4+ content in the soil. The results for Cgl showed an N-NO3- content of xylem sap that met the demand of NRA and were correlated with inorganic soil nitrogen, showing the responsiveness of species to N-NO3-. Hco was verified as less responsive to assimilation and high N-NO3- content in leaves. The species Ima showed an intermediate behaviour, which suggests the possibility of use of other nitrogen forms. The ecophysiological behaviours of the plants were related to the seasonal variation and indicate that these plants use strategies with different responsiveness to the use of soil N-NO3-. In this sense and considering that these species are typically used in ecological restoration projects in Brazil, the knowledge of a strategy for nitrogen use specific to each of them can assist in choosing the species appropriate to the edaphic conditions of the environment. [ABSTRACT FROM AUTHOR]

Nitrogen (N) wheat requirements in southeastern Buenos Aires province are determined by soil sampling at pre-planting (0-60 cm). Nevertheless, soil sampling at tillering could be a more precise tool for diagnosing N deficiencies due to N losses during initial stages of growing seasons as a consequence of excessive water in the soil profile. The objective of this study was to validate the methodology of N diagnostics and N application at planting or tillering at the different sites and years insoutheastern Buenos Aires province. An additional objective was to analyze the possibility of estimating N-NO3- levels up to 60 cm soil depths using soil N-NO3- contents up to 40 cm. In 6 of 10 sites, applications of N at tillering increased grain yield significantly compared to fertilization at planting. Relative yield (RY) was related to mineral N content (0-60 cm) at planting (r²= 0.73) or tillering (r²= 0.80). Response thresholds for 95% of RY were 152 kg N ha-1 and 126 kg N ha-1 for fertilization at planting or tillering, respectively. Soil N-NO3- content up to a soil depth of 60 cm was highly associated with N-NO3- content to the 40 cm depth for both sampling moments (r²= 0.98 and 0.90 for planting and tillering, respectively). Soil N-NO3- content from 0 to 60 cm can be estimated using soil N-NO3- content from 0 to 40 cm. [ABSTRACT FROM AUTHOR]

When animal husbandry is not included in organic farming systems, green manure may be crucial to preserve or increase soil organic matter content and to ensure an adequate N supply to crops. Different species, both legumes and nonlegumes, may be used as cover crops. The present research was carried out to investigate the effect of different green manure crops [oats and barley mixture (Avena sativa L. and Hordeum vulgare L.), rye (Secale cereale L.), brown mustard (Brassica juncea L.), flax (Linum usitatissimum L.), pigeon bean (Vicia faba L. var. minor)] on the production of the following tomato crop. A field trial was conducted for two cropping seasons (2003-2004 and 2004-2005) in a commercial organic farm. The yield of tomato crop was positively affected by pigeon bean, although statistically significant differences in comparison with the other treatments were observed only in 2004-2005, when the experiment was conducted in a less fertile soil. This was probably due mainly to the effect of the pigeon bean cover crop on N availability. In fact, this species, in spite of a lower biomass production than the other cover crops considered in the study, provided the highest N supply and a more evident increase of soil N-NO3. Also, cover crop efficiency, evaluated using the N recovery index, reached higher values in pigeon bean, especially in the second year. The quality of tomato fruits was little influenced by the preceding cover crops. Nevertheless, when tomato followed pigeon bean, fruits showed a lower firmness compared to other cover crops, and in the second year this was associated with a higher fruit N content. [ABSTRACT FROM AUTHOR]

During 3 consecutive years (1996/97–1998/99) the efficacy was studied of Triticale as a nitrogen (N) catch crop sown after the harvest of the potato crop cultivated in the preceding summer season under several N fertilizer treatments. In October, shortly after the harvest of the potatoes, there were registered significative differences in the soil N–NO3− levels among N fertilizer treatments of the potato crop. The higher values were recorded on the plots corresponding to higher N doses. At the end of winter, the N status of plants and at the end of experiments (late in April), the N–NO3− in soil, the biomass yield and the N uptake by the catch crop did not reflect the differences registered before in the soil inorganic N. This comparison may suggest that Triticale is little effective in recovering the residual inorganic N of the preceding crop due either to the rainfall occurring in the autumn or to the poor vegetative development of the catch crop during the autumn/winter period. However, at the date of cut, the catch crop removed up to 80 kg N ha−1. At this time, the soil N–NO3− levels were significantly higher on the fallowed plots. This result shows that the crop was very effective in uptaking the N that is mineralized after the end of winter. [Copyright &y& Elsevier]

Hermetia illucens L. known as Black Soldier Fly (BSF) is gaining worldwide interest as the most prevalent species in insect farming. In the current study, we evaluated under greenhouse conditions, the comparative performance of Black Soldier Fly Larvae (BSFL) frass as an organic fertilizer and a traditional organic amendment: cow manure (CM), on soil rhizosphere properties and durum wheat agro-morphological, physiological, and yield parameters. Both organic fertilizers were applied at doses of 7.5 t/ha (BSFL7.5 and CM7.5), 15 t/ha (BSFL15 and CM15) and 30 t/ha (BSFL30 and CM30). The results showed that applying BSFL frass with 7.5 and 15 t/ha had an acidifying as well as a desalination effect on soil compared to CM. The highest mineral nitrogen, phosphorus, and potassium contents were recorded in soils receiving 30 t/ha of BSFL frass. Microbial biomass was found to be improved by applying the lowest doses of BSFL frass. Durum wheat plants grown in pots treated with BSFL frass had the highest height, dry root weight, and chlorophyll indicators. The PCA analysis identified grain yield, yield component, and soil nutrients as major drivers for the variability among samples. Our results highlight the potential of BSFL frass to improve soil health and wheat yields in an environmentelly-friendly way. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Applied Ecology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study was to investigate the possibility of nutrient removal from landfill leachate using Chlorella sp. and its potential as agricultural fertilizer. Chlorella sp. was inoculated to a leachate suspension (1:1 ratio). Phosphate, ammonium and nitrate concentrations in the suspension and the dry cell weight of algae were measured at 0, 2, 4, 6 and 8 days of incubation. Then, the harvested microalgae biomass was mixed with a nutrient-poor soil at three levels: 0 (A0), 2 (A2) and 4 (A4) g 100 g−1. The mixtures were incubated for 2 months, and soil biochemical properties, including soil organic carbon (OC), available phosphorus (Pava), mineral nitrogen (Nmin), microbial basal respiration (MBR) and microbial biomass carbon (MBC), were determined in soil at 7, 14, 28, 35, 42, 49 and 56 days of incubation. The dry cell weight of the microalgae increased over time and removed ammonium, phosphate and nitrate from the leachate by 98.7, 92.7 and 56.9%, respectively. The added microalgae biomass to soil caused positive and significant changes in soil OC, Pava, Nmin, MBR and MBC. Therefore, it seems that Chlorella sp. cultivated in landfill leachate can be used as an agricultural fertilizer in soil. [ABSTRACT FROM AUTHOR]

Nitrification inhibitors applied to soil can reduce nitrogen (N) fertilizer losses by delaying the nitrification process and reducing nitrate losses to environment with enhanced N-fertilizer management. In this study, laboratory-scale experiments were carried out in order to evaluate the efficiency of nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) applied on urea and ammonium sulfate nitrate (ASN) sources under three tropical soils (Typic Quartzipsamment, Typic Hapludox and Rhodic Hapludox – contrasting soil textures). Soil samples were incubated over 60 days and the content of nitrate (N-NO3−), ammonium (N-NH4+) and pH variations were assessed periodically. In addition, N-NO3− and N-NH4+ percentage and nitrification inhibition were assessed. 3,4-Dimethylpyrazole phosphate application delays the nitrification process across all three tropical soil types, being more evident in the sandy-textured soils (Typic Quartzipsamment > Typic Hapludox > Rhodic Hapludox). DMPP application reduced the N-NO3− and N-NH4+ percentage in both ASN and urea sources, mainly between 15 and 30 (ASN) and between 7 and 30 days after N fertilization (urea). However, 45 days after N fertilization, inhibition of the nitrification process by DMPP is unlikely, regardless of N source. The nitrification process tended to be more intense when conventional urea was applied compared to conventional ASN. Therefore, the use of DMPP would benefit more urea than ASN mainly in sandy-textured soils, where the nitrification was observed to be increased. [ABSTRACT FROM AUTHOR]

It is well known that multiple interactions can occur between nitrogen and water use, depending on climate, soil and crop characteristics, in crop growth and yield development. However, little is known about the simultaneous change in both water and N use efficiency (WUE and NUE) and their possible interactions in cereal–-legume intercropping systems. In order to advance our knowledge on the N and water facilitation mechanisms involved in the intercropping responses of N and water input co-limitations, we investigated, via four experiment years, the simultaneous optimization of water and N-fertilizer inputs, as well as its possible effects on growth, yield, N acquisition, and the NUE and WUE in intercropped species. The results indicated that intercropping increases the leaf area index by more than +0.14 and +1.03 units when compared to durum wheat and chickpea monoculture systems, respectively. This increase is particularly noticeable under higher rainfalls during the crop period (i.e., as can be seen in the 2022, 2020, and 2019 seasons). Moderate N-application enhanced both the grain yield and protein accumulation in the mixed crops by more than 0.22 t ha−1 and 57 kg ha−1, respectively. Conversely, intercropping significantly decreased the mixed grain yield when compared to durum wheat monocultures. Intercropping advantages in terms of biomass (ranged from 1 to 44%) and N-acquisition (2 to 91%) was confirmed in either low- (2021) or high- (2019 and 2022) rainfall growing periods, but only under low and moderate N-applications. Improving N nutrition under both rainfall and drought growth periods was confirmed only for the mixed crops under all applied N-fertilizer doses. Such improvements in growth, N acquisition, and yield quality were most likely achieved by positive interactions (r2 = 0.73, p ≤ 0.001) between the NUE and WUE for the chickpea–wheat intercropping. Thus, 0.62 kg m−3 of WUE promotes a significant increase of 1 kg kg−1 in NUE by mixing chickpea-durum wheat. Rain-fed chickpea-durum wheat intercropping provides a higher performance in growth and yield quality compared to sole cropping systems; this may occur from the simultaneous optimizations of both water and N fertilizer inputs in low-N soil under semiarid conditions. [ABSTRACT FROM AUTHOR]

Nitrogen (N) deficiency could have a negative effect on sunflower (Helianthus annuus L.) yield and grain quality. Therefore, it is necessary to adjust the optimum rate, timing, and frequency of N fertilization to improve sunflower crop nutrition. Our objective was to evaluate the effect of N fertilization rate, timing, and splitting on grain yield, and grain and oil quality. Twelve field experiments were carried out between 2016 and 2020. Treatments consisted of at least three N rates ranging from 0 to 200 kg N ha−1 applied at V2. Moreover, the 80 kg N ha−1 rate was applied at V14 (80NV14) or split between V2 and V14 (80Nsplit). Treatments were evaluated in two sunflower genotypes, high oleic (HO) and conventional (CONV). A significant grain yield response to N fertilization was observed in six out of twelve experiments, generally at rates greater than 80 kg ha−1. The mean response to fertilization was 369 kg ha−1. Fertilization increased grain protein concentration (PG) (+1.5%) at experiments E1–E3 and E9–E12 and decreased oil concentration (OG) (−2%) at experiments E1, E4, E9, E11, and E12. The maximum N rate, increased oleic and stearic acid concentration (+3%–4%), depending on the genotype (AO and CONV). Neither fertilizer timing nor splitting affected grain yield or OG. Late N fertilization (V14) increased oleic acid (+2.4%), whereas it decreased linoleic acid (+2.2%). Based on our results, N fertilization can increase yield without negatively affecting commercial grain quality (OG and fatty acids concentration), regardless of fertilization timing and frequency. Core Ideas: Nitrogen fertilization at a rate >80 kg N ha−1 maximizes sunflower yield.Increases in N rate enhance oleic and stearic concentration.N fertilization at V14 increases protein concentration.Nitrogen timing and splitting do not affect yield nor grain quality. [ABSTRACT FROM AUTHOR]

O efeito de diferentes critérios para o manejo da adubação nitrogenada e do posicionamento de amostragem para a quantificação do N-NO3 residual no solo foi determinado após o cultivo do tomateiro adubado por sulcos. Dois experimentos foram conduzidos, no campo sem proteção, com aplicação de adubo sólido e irrigação por sulcos. Em cada experimento, os tratamentos foram arranjados em parcela subdivida, com dez critérios para o manejo da adubação nitrogenada na parcela e posições de amostragem do solo na subparcela. Esses foram arranjados no delineamento experimental de blocos ao acaso. Foi determinado o teor de N-NO3 no solo de amostras retiradas no final do ciclo de cada experimento, em diferentes posições. Em todos os experimentos o teor de N-NO3 residual no solo foi proporcional àquantidade de N aplicada nos diferentes critérios. Em condições de campo sem proteção e fertilizante nitrogenado aplicado em sulco, a melhor estratégia de amostragem do solo para a determinação do teor de N-NO3 residual foi obtida pela utilização de amostra composta tomada em posições sobre o sulco e entre o sulco e as plantas.Management of nitrogen fertilizer programs and sampling strategies to determine the levels of N-NO3 in the soil after growing tomatoes in fertilized furrows were studied. Two groups were studied, one without protection and another grown in an irrigated furrow in which a solid nitrogen fertilizer had been applied. In each plot, 10 treatments or criteria were evaluated. In each experiment, the treatments were arranged in a split-plot design, with 10 different nitrogen fertilizer conditions as the main treatment and soil sampling positions in a split-plot treatment. The sampling positions were arranged in a randomized complete block design. Soil N-NO3 levels were determined at the end of each sampling cycle. In all groups, residual soil N-NO3 levels were proportional to the amount of N applied. In fields without protection and nitrogen fertilizer applied to the furrow, the best strategy of soil sampling to determine the residual N-NO3 level was to use samples obtained from between the furrow and plants.

En el sudeste bonaerense, los requerimientos de nitrógeno (N) del cultivo de trigo son estimados mediante el muestreo de suelos en presiembra (0-60 cm), sin embargo, el muestreo en macollaje podría resultar una herramienta de diagnóstico más precisa debido a la ocurrencia de pérdidas de N al comienzo del ciclo del cultivo como consecuencia de excesos hídricos. El objetivo de este trabajo fue validar la metodología de diagnóstico para aplicaciones de N al momento de la siembra o al macollaje en diferentes sitios y años en el sudeste bonaerense, además de analizar la posibilidad de estimar el nivel de N-NO3 - hasta los 60 cm usando como variable el contenido de 0-40 cm. En 6 de 10 sitios, la aplicación de N al macollaje produjo incrementos significativos de rendimiento respecto de la siembra. El rendimiento relativo (RR) en grano se relacionó con el contenido de N mineral (0-60 cm) al momento de la siembra (r²= 0,73) o al macollaje (r²= 0,80). Los umbrales de respuestas para el 95% del RR fueron de 152 kg N ha-1 y 126 kg N ha-1 para la fertilización al momento de la siembra y macollaje, respectivamente. Se determinó una estrecha asociación entre el contenido de N-NO3 - hasta los 60 y 40 cm de profundidad para los muestreos al momento de la siembra (r²= 0,98) y al macollaje (r²= 0,90). El contenido de N-NO3 - hasta los 60 cm para ambos momentos de muestreos puede ser estimado mediante el muestro de suelo hasta los 40 cm de profundidad.Nitrogen (N) wheat requirements in southeastern Buenos Aires province are determined by soil sampling at pre-planting (0-60 cm). Nevertheless, soil sampling at tillering could be a more precise tool for diagnosing N deficiencies due to N losses during initial stages of growing seasons as a consequence of excessive water in the soil profile. The objective of this study was to validate the methodology of N diagnostics and N application at planting or tillering at the different sites and years insoutheastern Buenos Aires province. An additional objective was to analyze the possibility of estimating NNO 3 - levels up to 60 cm soil depths using soil N-NO3 - contents up to 40 cm. In 6 of 10 sites, applications of N at tillering increased grain yield significantly compared to fertilization at planting. Relative yield (RY) was related to mineral N content (0-60 cm) at planting (r²= 0.73) or tillering (r²= 0.80). Response thresholds for 95% of RY were 152 kg N ha-1 and 126 kg N ha-1 for fertilization at planting or tillering, respectively. Soil N-NO3 - content up to a soil depth of 60 cm was highly associated with N-NO3 - content to the 40 cm depth for both sampling moments (r²= 0.98 and 0.90 for planting and tillering, respectively). Soil N-NO3 - content from 0 to 60 cm can be estimated using soil N-NO3 - content from 0 to 40 cm.

Until now, the solubilization capacities of insoluble mineral P by soil microorganisms have been screened in vitro with media containing NH4+ as a nitrogen source. This presence of NH4+ will lead to an acidification of the medium responsible for the solubilization of the insoluble P. However, besides proton release, the production of organic acids can play a very important role in the release of free P. This physiological mechanism can largely depend on the source of nitrogen (NH4+vs NO3-) assimilated by the bacteria but the influence of the N source on the production of organic acids has yet to be studied. Our aim was to investigate if the N source assimilated by bacteria and the soil characteristics such as the dominant N source (NH4+vs NO3-) and CaCO3 contents might influence the bacterial capacities to solubilize rock phosphate. To fill this objective, we screened the capacity of bacteria isolated from 3 soils to solubilize rock phosphate in vitro in presence of NH4+or NO3-. Then, we selected the most efficient bacterial strains to identify and quantify the release of organic anions into the medium. Among the two hundred and forty-three bacterial strains isolated from the 3 soils, nine and seven isolates were identified with the highest % rock phosphate-solubilization values with NH4+ or NO3- as the sole N-source. Only one strain was able to release free Pi with NH4+ or NO3- as the sole N-source. The most predominant organic acids released by almost all isolates were gluconic acid, lactic acid, glycolic acid, acetic acid, formic acid and pyruvic acid regardless the N-source. However, with NO3- as source of N, the highest concentrations on those acids were found together with the highest release of free Pi into the medium. Molecular analysis of 16S rRNA indicated that almost all strains belonged to Bacillus and Paenibacillus genera. The PCA analysis between soil properties and bacterial capacities to release organic acids and free Pi also revealed that soil factors such as CaCO3 and soil NO3- content positively influenced the release of organic acids by bacteria grown in vitro. Our results concluded that the bacterial rock phosphate-solubilization was intimately related to organic acids production which in turn seemed to be driven by the assimilation of NO3- by bacteria. Therefore, the N-source might be considered a key factor to take into consideration during the screening and selection of suitable strains involved in the P-solubilization. [ABSTRACT FROM AUTHOR]

Cereal yields tend to be higher in cereal–legume rotations relative to cereal monoculture yields. We investigated the influence of crop rotation on yield and input-use efficiency in high-yield irrigated maize (Zea mays L.)-based cropping systems using producer-reported data from western U.S. Corn Belt (about 11,000 observations). Across regions, average yield of maize grown after soybean [Glycine max (L.) Merr.] (S–M) was 0.2 to 0.6 Mg ha-1 (2–5%) higher, relative to yield of maize grown after maize (M–M). Soybean yield was 5% greater after two consecutive maize crops (M–M–S) than after only 1 yr of maize (S–M–S). Nitrogen fertilizer rate in maize fields was 13 kg N ha-1 (6%) lower in S–M than M–M fields, which, together with higher maize yields in S–M fields, resulted in 11% higher nitrogen partial factor productivity (PFPN). Difference in PFPN was unrelated with residual soil N–NO3– from prior crop. Analysis of rotation data indicated that rotation effect persists across a wide range of maize yields, from 6 to 15 Mg ha-1, though magnitude of rotation effect decreases with increasing yield level. Trends toward greater proportion of total maize area in S–M, rather than M–M, accounts for 8% of maize yield gain in U.S. Corn Belt since 1970. Similarity between our findings and previous research highlights the opportunity to quantify impact of management on yield and efficiencies by using producer data as a complement to high-cost multi-year, multi-site field experiments. [ABSTRACT FROM AUTHOR]

Given the growth in the number of biogas power plants and the increase in the generation of waste from energy production, it is relevant to study the sustainable nature of this waste. Digestate is a product of the anaerobic digestion process, and is a valuable bio-fertilizer containing organic matter and nutrients necessary for agricultural plants' growth. The study showed that different rates of liquid and solid phases of anaerobic digestate influenced the contents of carbon and nitrogen in genetically young soil in alluvial deposits—Fluvisol. The application of solid digestate (SD) considerably increased soil organic carbon content (SOC) in the 0–10 cm soil layer; however, SOC did not reach the 20–30 cm layer. Liquid digestate (LD) significantly increased SOC in the deeper layers. The levels of mineral nitrogen (Nmin) and water extractable organic carbon (WEOC) increased in the 0–10 cm soil layer soon after fertilization with LD and SD. The mobile components of the soil (Nmin and WEOC) were characterized by high variability during the growing season. Within the 2-month period, their concentrations decreased drastically and were close to those of unfertilized soil. The research indicates that anaerobic digestate had a greater effect on mobile forms of carbon and nitrogen in the soil than on their total amounts. [ABSTRACT FROM AUTHOR]

Biogas slurry is widely used to fertilize crops. However, their impact on soil parameters and waxy winter wheat (Triticum aestivum L.) nutrition is poorly understood. The aim of this research was to determine the influence of liquid anaerobic digestate and pig slurry applied to waxy winter wheat on the dynamics of soil organic carbon (SOC) and total nitrogen (Ntot) in different forms on grain yield, and to compare them with the use of ammonium nitrate. The nitrogen rates (kg N·ha−1) used for fertilization were N0, N60, N120, and N120+50. The study showed that the variation of nitrate nitrogen (N-NO3) and water-extractable organic carbon (WEOC) in the soil during the growing season depended on N fertilizer rates, meteorological conditions of the year, and, to a lesser extent, on fertilizer forms. Meteorological conditions were responsible for the demand and supply of nutrients from the soil by the waxy winter wheat variety. This determined the wheat yield and the variation in the soil parameters studied. Over the 2 years, the soil C:N ratio decreased, especially at the medium and high N fertilizer rates. The lowest changes were observed in the unfertilized and fertilized plots at a rate of 60 kg N·ha−1. [ABSTRACT FROM AUTHOR]

To study the effect of different defoliation regimes on light interception, forage yield, spring regrowth and quality of one of the most expanded species in this region, Chloris gayana, we evaluate combinations of two defoliation frequencies (300 and 500 GDD) and two intensities (1 and 3 green stubble leaves) in a controlled experiment that comprised 1500 GDD during summer and autumn. Defoliation frequency had a greater effect on the evaluated traits than defoliation intensity. Forage yield was lower under the higher (300 GDD) than under the lower (500 GDD) frequency defoliation (6699 vs. 8961 kg DM/ha, respectively), but forage showed higher leaf percentage (69.8 vs. 53.2%) and better nutritional value at 300 GDD (17.4 vs. 15.6%, 64.1 vs. 62.1%, 60.9 vs. 63.2% and 67.7 vs. 62.4% of crude protein, dry matter digestibility, neutral detergent fiber and its digestibility, respectively) than at 500 GDD. Spring tiller density was not affected by any of the defoliation regimes. Better livestock performance could be obtained by grazing at 300 GDD, but considering the whole growing season, more digestible dry matter is likely to be produced under defoliations every 500 GDD than every 300 GDD. [ABSTRACT FROM AUTHOR]

The sustainability of woody crop agroecosystems requires continued improvements to water, nutrient and soil management. In this work, the combination of resource availability or fertigation dose with soil management practices was tested in a 2 × 2 factorial design in a drip irrigated young almond orchard. The fertigation doses were: the farmer supply at 60% of crop evapotranspiration and full nutrient requirements and the half-farmer supply at 30% of crop evapotranspiration and half nutrient requirements. The soil management practices were: bare soil and cover crops in the inter-row (mixture of grasses and legumes). Tree growth, yield, water and nutrient status, and cover crop biomass and nutrient status were determined, as well as inter-row soil C and N concentration. Results showed that the effect of resource availability was independent of soil management and vice versa. The half farmer treatment reduced tree vegetative growth and yield compared to farmer treatment, due to a negative effect on the water status, without observing a decrease in the concentration of nutrients in leaves or fruit. Trees with cover crop also reduced growth and yield compared to bare soil management. This was due to a nutritional competition, mainly of Ca, Fe, Mn and Zn, rather than to a decline in tree water status. Cover crops sequester up to 1 t/ha/year of carbon but do not increase soil organic carbon, nor soil total nitrogen. Cover crops proved to be efficient in reducing soil nitrate concentration in the topsoil and therefore has potential to prevent its leaching. Deficit fertigation and the use of cover crops can be effective practices to preserve and save water and nutrient resources in Mediterranean agroecosystems, but should be established with caution so as not to compromise the profitability of the orchard. [ABSTRACT FROM AUTHOR]

Nitrous oxide (N2O) is the main greenhouse gas (GHG) emitted from agricultural soils as a by-pass product of nitrification and denitrification processes. The Intergovernmental Panel on Climate Change (IPCC) excluded from its GHG inventory guidelines in 2006 the Nitrogen Biological Fixation (NBF) as a source of N2O emissions by crop legumes, due to the lack of solid scientific evidenceon the existence of these emissions. However, at present the actual amount of N2O emissions by crop legumes in the field is still under investigation, with special emphasis on soybeans which are is the main commodity produced by Argentina and a main biodiesel source. The influence of NBF on N2O emissions can be tested using nonnodulating soybean varieties. This study aims to compare and analyse N2O emissions from nodulating and non-nodulating soybean varieties in order to clarify the actual influence of this commodity on field GHG emissions. Gas samples were collected from closed non-vented chambers. N2O emissions ranged from -9 to +15 μg N-N2O m-2 h-1 and only in the last sampling date, values differed significantly between treatments (non-nodulating > nodulating soybean). N2O emissions were positively related with soil N-NO3 concentration and soil water-filled pore space (WFPS). Results show that in this field study, NBF caused only a slight impact on N2O emissions. These results agree with the latest IPCC guidelines in 2006 for GHG inventories. [ABSTRACT FROM AUTHOR]

three-year field experiment was conducted under conditions of Luvic Chernozem soil. Diversified nitrogen fertilization with 0, 60, 120, and 180 kg N ha-1, and microbial preparations improving soil properties were applied to potatoes, cv. 'Satina', cultivation. N-NO3 concentration in the soil profile (0-0.9 m) in autumn after potato harvesting fluctuated from 28 kg N ha-1 in the N0 treatment to 70 kg N ha-1 in the N180 treatment, whereas N-NH4 content varied from 22 to 48 kg N ha-1, respectively. The level of nitrogen fertilization also had a significant effect on the change in soil N-NO3 content during the autumn-winter period. The decrease in N-NO3 content in the N0 treatments was 7% compared to 24% in the N180 treatments. Application of microbial preparations to potato cultivation caused an increase in Nmin content in soil after crop harvesting. However, after the autumn-winter period, a lower amount of N-NO3, compared to the control treatment, was found in the treatments where microbial preparations had been used. [ABSTRACT FROM AUTHOR]

Aims: The aim of the study was to investigate N biogeochemistry of four neighboring, high mountain plant communities and to identify main factors which drive variability among them. We hypothesized that the vegetation types differ in terms of N transformations, and that spatial differentiation of the communities and dominant growth form can reflect an existence of several N-environments along an elevational gradient. Methods: Plant and soil N characteristics were studied in four vegetation types: heathland, scrub, sward and tall forb. Leaf nitrate reductase activity and total N were measured in the dominant species. Soil pH, total C, N, inorganic and dissolved organic N concentrations were measured. The soil net N mineralization rate was examined. Results: The DistLM and PERMANOVA analyses revealed that variability among the vegetation types was driven primarily by elevation, soil N–NH4+, soil pH and soil total C. We identified three distinct N-environments along an elevational gradient. The "N-poor alpine" located at the highest altitudes, strongly N-limited and dominated by dwarf-shrub. The "N-mixed subalpine" located in the middle of the gradient and covered by scrub and sward. It was characterized by moderate N turnover rate. The "N-rich subalpine" occurred at lowest locations and was covered by subalpine tall forb community. It exhibited the highest dynamics of N transformations and was rich in inorganic N. Conclusion: Three main N-environments were identified: N-poor alpine, N-mixed subalpine, N-rich subalpine. Variability among the vegetation types was driven primarily by elevation, soil N–NH4+, soil pH and soil total C. [ABSTRACT FROM AUTHOR]

This study was designed to investigate the effects of Azospirillum brasilense and Bradyrhizobium sp. co-inoculation coupled with N application on soil N levels and N in plants (total N, nitrate N-NO3− and ammonium N-NH4+), photosynthetic pigments, cowpea plant biomass and grain yield. An isotopic technique was employed to evaluate 15N fertilizer recovery and derivation. Field trials involved two inoculations—(i) single Bradyrhizobium sp. and (ii) Bradyrhizobium sp. + A. brasilense co-inoculation—and four N fertilizer rates (0, 20, 40 and 80 kg ha−1). The co-inoculation of Bradyrhizobium sp. + A. brasilense increased cowpea N uptake (an increase from 10 to 14%) and grain yield (an average increase of 8%) compared to the standard inoculation with Bradyrhizobium sp. specifically derived from soil and other sources without affecting 15N fertilizer recovery. There is no need for the supplementation of N via mineral fertilizers when A. brasilense co-inoculation is performed in a cowpea crop. However, even in the case of an NPK basal fertilization, applied N rates should remain below 20 kg N ha−1 when co-inoculation with Bradyrhizobium sp. and A. brasilense is performed. [ABSTRACT FROM AUTHOR]

Seed inoculation with beneficial microorganisms has gained importance as it has been proven to show biostimulant activity in plants, especially in terms of abiotic/biotic stress tolerance and plant growth promotion, representing a sustainable way to ensure yield stability under low input sustainable agriculture. Nevertheless, limited knowledge is available concerning the molecular and physiological processes underlying the root‐inoculant symbiosis or plant response at the root system level. Our work aimed to integrate the interrelationship between agronomic traits, rhizosphere microbial population and metabolic processes in roots, following seed treatment with either arbuscular mycorrhizal fungi (AMF) or Plant Growth‐Promoting Rhizobacteria (PGPR). To this aim, maize was grown under open field conditions with either optimal or reduced nitrogen availability. Both seed treatments increased nitrogen uptake efficiency under reduced nitrogen supply revealed some microbial community changes among treatments at root microbiome level and limited yield increases, while significant changes could be observed at metabolome level. Amino acid, lipid, flavone, lignan, and phenylpropanoid concentrations were mostly modulated. Integrative analysis of multi‐omics datasets (Multiple Co‐Inertia Analysis) highlighted a strong correlation between the metagenomics and the untargeted metabolomics datasets, suggesting a coordinate modulation of root physiological traits. [ABSTRACT FROM AUTHOR]

Silver scurf, caused by the fungus Helminthosporium solani, is an important disease affecting potato tubers. Control of the disease has been hampered by the development of H. solani strains resistant to thiabendazole. Currently, there is no alternative to thiabendazole for the efficient control of the disease. In this study, 45 selected soils from the province of Que´bec were tested in greenhouse assays for their effect on silver scurf development. The results showed that soil influenced significantly silver scurf development and that specific soils displayed an interesting level of suppressiveness against potato silver scurf. Investigations into the cause(s) of soil suppressiveness revealed on the one hand, significant negative correlations between silver scurf severity and soil N-NO3 and available Fe contents, and on the other hand, absence of significant correlations between silver scurf severity and the different soil microbial populations. Investigations also revealed the presence of microorganisms antagonistic to the pathogen in the most suppressive soils. The antagonist microorganisms isolated in those soils were Bacillus cereus, Cellulomonas fimi, Kocuria varians, Pseudomonas putida, Rhodococcus erythropolis and Rhodococcus globerulus. Considering that few microorganisms were previously reported to display antagonism against H. solani, these results open the way to new avenues of investigation towards achieving biocontrol of silver scurf. [Copyright &y& Elsevier]

Abstract Little is known about the effect of combined phosphorus and nitrogen (P-N) fertilization on the N requirement of sunflower (Helianthus annus L.). This study was carried out to evaluate the effects of varying levels of P and N, as well as the interaction P × N, on the N uptake, yield and N apparent utilization efficiency under field conditions. Split-plot design experiments were conducted in the mid-western Pampas in Argentina. Four levels of N (0, 46, 92 and 138 kg N ha-1 ) and three levels of P (0, 12 and 40 kg P ha-1 ) were applied to two Typic Hapludolls over two growing seasons (1997–98 and 1998–99). N uptake and soil N-NO3 contents were determined at the V7 , R5 and R9 growth stages. The sunflower yield ranged from 2.5 to 5.0 Mg ha-1 . The total N requirement was around 45 kg N Mg-1 grain, and this result suggests that it is not necessary to use different N requirements (parameter b) for fertilized crops when a yield response is expected. To achieve a 100 % yield maximum a N supply (soil plus fertilizer) of 181 kg N ha-1 at P40 was needed. However, at P0 , the highest yield was about 80 % of the maximum yield with a N supply (soil plus fertilizer) of 164 kg N ha-1 . P application increased the apparent use efficiency of the supplied N. [ABSTRACT FROM AUTHOR]

ABSTRACT Grazing intensity is a preponderant factor for the success of integrated crop-livestock systems (ICLS). Management of grazing intensity impacts soil organic matter (SOM) dynamics, soil reacidification process, and amount and quality of residues added to the ICLS. Consequently, the soil mineral nitrogen (N) forms may present different behavior throughout the pasture cycle, because they are directed linked to SOM and soil acidity dynamics. This study aimed to evaluate the impact of grazing intensities and liming in the temporal variation of acidity and mineral N forms in soil surface (0.00-0.20 m) and subsurface (0.20-0.40 m), throughout the pasture cycle of an ICLS under an Oxisol in the Brazilian subtropics. The study was performed 11 years after the beginning of the field experiment, characterized by the cattle grazing in a winter pasture of oat + ryegrass during the winter and soybean cropping during the summer. The experimental design is randomized block with three replicates, where the grazing intensities are in the plots and liming is the subplots. The grazing intensities were defined as grazing sward height management, being 0.10, 0.20-0.30, and 0.40 m defined as intensive (IG), moderate (MG) and light grazing (LG), respectively. We evaluated the soil ammonium (N-NH4+), nitrate (N-NO3-), mineral N and pH at 45, 70, 156 and 192 days after pasture sowing (DAPS). Our results showed that grazing intensities only affected the soil pH at the end of pasture cycle, with MG presenting higher pH than IG and LG, regardless of liming. A decrease of soil N mineral stocks was observed throughout the pasture cycle in all managements, due to the decrease of soil N-NO3- stocks in the surface and subsurface layers and of N-NH4+ only in the surface layer. The influence of grazing intensities was only observed for N mineral forms in limed areas before the beginning of grazing. At 45 DAPS, MG and LG presented the highest and the lowest N-NH4+, respectively. At 70 DAPS, the behavior was inverse, and LG presented the highest N-NO3- stock and the MG and IG the lowest N-NO3- stocks. With such results, it is possible to conclude that there is an influence of grazing intensity and liming in the temporal variation of soil pH and mineral N forms in ICLS and this may be utilized for improvements in N fertilizer management, mainly before the starting of winter grazing.

Purpose: The use of nitrification inhibitors could be an interesting alternative when applied to enhance nitrogen (N) fertilizer use efficiency in annual crops such as cotton under tropical soil conditions. Thus, our aim was to evaluate the efficiency of the nitrification inhibitor 3,4-Dimethylpyrazole phosphate (DMPP) in a typical tropical soil by evaluating the fate of nitrogen (N-NO3−, N-NH4+ and total N in soil and leached water), N accumulation and N recovery by cotton plants and soil. Methods: Leaching columns with cotton plants were used to assess N-NO3− and N-NH4+ losses in drainage water. The treatments consisted of three N levels applied in side-dressing (corresponding to 50, 100 and 150 kg N ha−1) as 15N-urea with and without DMPP application. An additional treatment (absence of N application in side-dressing) was used as a control. Results: 3,4-Dimethylpyrazole phosphate efficiently improved N recovery after urea fertilizer was applied to plants and in the soil by reducing NO3− leaching, leading to enhanced N acquisition from fertilizer and soil and augmenting N accumulation in plants, mainly when high N levels above 100 kg N ha−1 were applied. We found that total N recovery increased 31% when 150 kg N ha−1 was applied as a urea + DMPP source compared to the application of conventional urea. In addition, DMPP application reduced NO3− leaching losses (by approximately 11 to 20%), although it had no significant effect on the shoot or root dry matter yields. Conclusion: The reduction in NO3− leaching losses obtained herein highlights the potential of DMPP to mitigate the impact of increased urea inputs on leaching losses, thereby improving N use efficiency and N uptake in cotton crops. [ABSTRACT FROM AUTHOR]

Rice root exudates can control nitrification by releasing biological nitrification inhibitors (BNIs), reducing nitrogen losses in agricultural soils. However, the inhibitory effect on nitrification and the abundance of ammonia oxidisers in different soil types remain unclear. Two temperate paddy soils with different organic matter contents were collected to investigate the impact on nitrification rates of two rice cultivar root exudates, El Paso 144 (O. sativa ssp. indica) and Tacuarí (O. sativa spp. japonica). Root exudates were extracted before the tillering growth stage, and their BNI potential was evaluated in a bioassay with luminescent Nitrosomonas europaea and in a 12-day soil microcosm incubation. While exudates from Tacuarí showed stronger BNI activity in the bioassay, its nitrification inhibition in both soils was similar to that of DCD. El Paso did not show BNI activity in Salto whose organic matter content was higher. The abundance of ammonia oxidisers was not affected by root exudates or DCD, but only ammonia-oxidising bacteria had a significant positive relationship with soil nitrate. Our results demonstrated that although the bioassay showed high BNI activity, its expression in soils varied depending on the rice cultivar and the type of soil, particularly with its organic matter content. [ABSTRACT FROM AUTHOR]

As the market indicates a growing interest in organically grown fruit, there is a need for biostimulants to counter the adverse effects of pathogenic fungi and fungal-like-pathogens. Four microbial pathogens (Botrytis cinerea , Verticillium sp., Phytophthora sp., and Colletotrichum sp.) which are the most often causes of strawberry diseases were selected. Five kinds of biostimulants (C1, C2, C3, C4, and C5) containing bacterial consortia were developed to combat the pathogens. The antagonistic effect of selected microorganisms against strawberry pathogens was observed. The effectiveness of various beneficial bacteria in combating fungal pathogens of cv. Honeoye strawberries was compared and the impact of their activity on fruit quality was assessed. The most significant effect on the strawberry firmness was found for the C2 consortium, which provided the strawberries infected with the pathogens group (MIX: B. cinerea , Verticillium sp., Phytophthora sp., and Colletotrichum sp.) with a 140% increase in maximum load in a puncture test compared to the positive control (C0). Strawberries contaminated with Phytophthora sp. after the application of Consortium C4 (C4) showed the largest increase (127%) in soluble solid content (SSC) when compared to the C0. Fruit contaminated with Colletotrichum sp. and B. cinerea after the application of C2 and Consortium 5 (C5), respectively, had the highest levels of anthocyanins and total phenolic content, when compared to C0. The largest increase, which reached as high as 25%, in D-galacturonic acid content was observed for the group of pathogens after Consortium 1 (C1) application. The extraction of strawberry pectin allowed for the study of the rheological properties of pectin solutions; on this basis, strawberry pectin from the control (NC) was distinguished as it showed the highest viscosity (0.137–0.415 Pas). Taking into account the individual effects of bacteria on strawberry pathogenic fungi and fungal-like-pathogens, it is possible to reduce the adverse effects of fungal disease and to improve the properties of strawberries by selecting the appropriate bacterial consortium. Interactions between microorganisms are often complex and not fully understood, which suggests the need for further research in this direction. [ABSTRACT FROM AUTHOR]

Environmental conditions contribute to a large percentage of wheat yield variability. This phenomenon is particularly true in rainfed environments and non-responsive soils to N. However, the effect of P application on wheat is unknown in the absence of N fertilizer application. This study was conducted from 2012 to 2019 in permanent beds established in 2005. Treatments were arranged in a split-plot design and consisted of superimposing three P treatments (foliar, banded and broadcast application) plus a check (0P) within each one of four preceding N treatments (applied from 2005 to 2009). Foliar P generally showed a greater response than granular P treatments even though the soil tests high P (>30 mg/kg). Precipitation estimated for two different growth intervals explained through regression procedures the Years' effect. Seasonal precipitation (224–407 mm) explained variation of relative yield, N harvest index (NHI) and P agronomic efficiency (AE). Reproductive stage precipitation (48–210 mm) explained soil N supply. In dry years, foliar P application improved predicted relative yield 14% and AE 155 kg grain/kg P compared to granular P treatments. Similarly, soil N supply increased 15 kg/ha in dry moisture conditions during the reproductive stage. The NHI consistently improved over the crop seasons. This improvement was relatively larger for 0 kg N/ha. On average, NHI increased from about 0.57 to 0.72%. Normalized difference vegetation index (NDVI) readings at the booting growth stage were negatively associated with NHI. Foliar P in this non-responsive soil to N showed the potential to replace granular P sources. However, the omission of granular P needs to be further studied to estimate the long-term effect on the soil P test. [ABSTRACT FROM AUTHOR]