Nitrogen Fertilizer Treatments Research Articles

Plant Growth of Beetroots (Beta vulgaris L.) with Nitrogen Supply at Suboptimal Elevations in a Tropical Region

The present study was designed to study the possibility of beetroots to be cultivated at suboptimal elevations in the tropics. Four pot experiments were conducted in the field each at 1700, 850, 520 and 320 m asl (above sea level) in the region of Malang, East Java. A randomized block design with four replicates was used to impose the treatment of nitrogen (N) fertilizer consisting of 0, 0.4, 0.8 and 1.2 g N/plant (~ 0, 100, 200 and 300 kg N/ha). In the experiments at the elevation of 1700 m and 320 m asl, the treatment of 0 and 80 g chicken manure per plant (~ 0 and 20 t/ha) was involved. The treatment of 0 and 0.6 g P2O5 and 0 and 0.8 g K2O per plant was involved in the experiment at 850 m and 520 m asl respectively. Plant growth (total dry weight, leaf area and leaf number) was observed on day 20, 40, 60 and 90 after sowing by destructive plant samplings. In the present paper, data were reorganized to analyze the effect of elevation and N fertilizer on plant growth with the elevation as the main factor and N fertilizer as the sub factor.

Temperature-Associated Effects on Flavonol Content in Field-Grown Phaseolus vulgaris L. Zolfino del Pratomagno

Combining the need to increase local Phaseolus vulgaris L. production, with the objective of identifying which abiotic inductors (irrigation and temperature) and/or elicitors (nitrogen fertilizer treatment) can be used as potential strategies to improve flavonol content, open-field experiments were conducted in Pisa and Bologna (Italy) over two years, using the local landrace of interest “Zolfino del Pratomagno”, and a commercial variety, Verdone. Full-irrigation and nitrogen treatment, individually, and in combination, increased yield and decreased flavonols, respectively, in both genotypes and locations. Yield, under all treatments, was significantly higher in Pisa (17.5–21.9 °C) than Bologna (21.4–24.8 °C) for Verdone, but was the equivalent for Zolfino. An inverse correlation between average mean temperature and flavonol content was evident only in Zolfino. The feasibility of increasing dietary flavonol production using decreasing temperature as a strategy with some degree of control was then tested by cultivating Zolfino at different altitudes (108 (24 °C) to 800 m a.s.l. (18 °C)) in Pratomagno. Increasing the altitude induced a significant 3-fold increase in seed-coat kaempferol glycosides, comprising more than 95% of the total flavonols. Temperature-associated effects on flavonol synthesis warrants consideration when selecting a cultivation environment to augment the kaempferol-based, anticarcinogenic benefits of Zolfino.

Optimizing nitrogen fertilization rate to enhance soil carbon storage and decrease nitrogen pollution in paddy ecosystems with simultaneous straw incorporation

Nitrogen fertilization (NF) is an important agricultural management practice that greatly affects soil carbon (C) storage through regulating the balance of soil C input (straw biomass) and output (ecosystem respiration), especially for agroecosystems with simultaneous straw incorporation (SI). However, little is known about how different NF rates affect soil C balance (net ecosystem carbon budget, NECB) in flooded paddy ecosystems with SI. We conducted a two-year field experiment in a typical rice–wheat cropping system in southern China to investigate the response of soil C input (net primary production (NPP) and SI), output (ecosystem respiration and methane emissions), and NECB and N losses under five different NF rates (0/0, 120/90, 180/135, 240/180 and 300/225 kg N ha−1 for the rice/wheat season). Straw harvested from previous cropping season was chopped and fully incorporated into the soil prior to the next season. Our results showed that all treatments had a positive NECB value ranged between 4057–14380 kg C ha−1 yr−1. Compared with the no NF, NF treatments clearly increased the annual NECB by 17.2 %–185 % depending on NF rate. A 20 % reduction relative to the local NF rate (525 kg N ha−1) increased annual crop yield by 4.1 %–6.7 % and NECB by 9.6 %–16.8 %, which was attributed to the increase in NPP (2.6 %–6.2 %) and straw C input (3.8 %–6.1 %), and the decrease in ecosystem respiration (1.8 %–2.1 %) and methane emissions (8.4 %–10.4 %). Moreover, total reactive N losses were significantly decreased by 21 %. However, further reducing the rate by 40 % from local NF rate significantly decreased crop yield by 12.7 %–14.9 % and NECB by 16.7 %–19 %, mainly due to the significant decrease in soil C input through NPP by 14 %–18 % and straw C input by 7.4 %–15.8 % as the inadequate N supply impaired crop growth. Our results suggest that optimizing NF rate is effective in further enhancing soil C storage, decreasing N pollution and sustaining food security in paddy ecosystems with simultaneous SI.

Влияние длительного периодического внесения удобрений на структуру древостоя и напочвенного покрова в условиях среднетаежных сосняков брусничных (Республика Карелия)

The results of research on studying the influence of after-effects of periodic nitrogen (N) and complex fertilizer (NPK) treatments on the structure of the tree layer and ground cover are reported. The study objects were pine plantations growing on poor sandy soils in the cowberry pine forests (Karelian taiga district and middle taiga). At the time of survey, the plantations were 53 years old; fertilizers were last applied 30 years ago. A geobotanical releve was carried out, stand valuation characteristics were determined, and microphytocoenoses were mapped at each sample plot. The NPK fertilization resulted in an increase in the average diameter and height of the pine plantations with more intensive thinning of the stand in comparison to the control and nitrogen fertilizer treatments. The fertilizer and control treatments are the same according to the total number of species in the ground cover. At the same time, signifcant differences were observed in the ratio of projective covers of mosses and lichens. In all fertilized plots, the abundance of mosses was twice or even more higher than the abundance of lichens, whereas the moss cover at the control site was almost the same as the lichen cover, and locally even lower. This pattern is probably associated with the response of true mosses to elevated carbon and nitrogen content in upper soil horizons. The only stand valuation characteristic reliably and unambiguously correlating with the ground cover structure is the average diameter: the larger the value of the average diameter, the larger the projective cover of true mosses. Generally speaking, four-time mineral fertilization with 5 year intervals of pine plantations growing on sandy soils continue to exert an effect on the structure of the tree layer and ground cover even 30 years after the last treatment. In the fertilized sample plots, elevated nitrogen and carbon levels are observed only in the forest floor and the soil horizon directly underlying the floor. This is due to the fact that trace amounts of nitrogen are fxed in the phytocenosis and released back with litter fall only into the topmost soil horizons; influencing the structure of the moss-and-lichen layer towards the prevalence of true mosses(Pleurozium schreberi, Hylocomium splendens) over fruticose lichens of the genus Cladonia in the ground cover. For citation: Genikova N.V., Kharitonov V.A., Kryshenʼ A.M. The Effect of Long-Term Periodic Fertilization on the Structure of the Stand and the Ground Cover in the Cowberry Pine Forests of Middle Taiga (Republic of Karelia). Lesnoy Zhurnal [Russian Forestry Journal], 2020, no. 2, pp. 35–50. DOI: 10.37482/0536-1036-2020-2-35-50 Funding: The research is federally funded within the framework of the state assignment of the KarRC RAS (Forest Research Institute).

Effects of synthetic fertilizer and farm compost on soil nematode community in long-term crop rotation plots: A morphological and metabarcoding approach.

Soil biodiversity plays a key regulation role in the ecosystem services that underpin regenerative sustainable agriculture. It can be impacted by agricultural management techniques, both positively (through measures such as compost application) and negatively (through, for example, application of synthetic nitrogen). As one of the most numerous members of the soil biota, nematodes are well established as indicators for the soil food web. However, compost application also includes the addition of nematodes present in compost and their subsequent survival in soil is unknown. Nematode communities within the compost applied to soil, and nematode communities in the soil of a multi-year rotational cropping field trial in Melle (Belgium) were studied using morphological and metabarcoding techniques. Compost (C) and nitrogen fertilizer (NF) treated plots were compared. Three replicate plots were investigated for each of the following treatments: C application only; C and NF application; NF only; no C and no NF (control). Plots were sampled six times between 2015–2017, before and after C or NF were added each spring and after crop harvest (except for 2017). NF treatment resulted in a significant decrease of fungal feeding and predatory nematodes, while herbivorous nematodes were positively affected. Remarkably, we did not find compost addition to exert any noticeable effects on the soil nematode community. The morphological and metabarcoding data resulted in different results of the nematode community composition. However, trends and patterns in the two data sets were congruent when observed with NMDS plots and using the nematode maturity index. Metabarcoding of individual compost nematode taxa demonstrated that nematodes originating from compost did not persist in soil.

Effects of phosphogypsum and water treatment residual application on key chemical and biological properties of clay soil and maize yield

AbstractThe reuse of phosphogypsum (PG) and water treatment residual (WTR) waste for agricultural purposes is a possible option to improve the soil properties and increase the crop yield. The present study was conducted during the 2014 growing season in order to determine the impacts of PG and WTR applied to the heavy clay soils (which contain more than 50% clay particles) at rates of 5 and 10 t ha−1 with the recommended nitrogen fertilizer (NF) on the key soil properties and maize yield. A field experiment was conducted as a randomized complete block design with five treatments and three replications. The treatments were as follows: recommended nitrogen fertilizer (NF); NF+PG at 5.0 t ha−1 (NF+PG5); NF+PG at 10.0 t ha−1 (NF+PG10); NF+WTR at 5.0 t ha−1 (NF+WTR5); and NF+WTR at 10.0 t ha−1 (NF+WTR10). The results revealed that the soil microbial biomass carbon (MBC), CO2 evolution and dehydrogenase activity (DHA) increased significantly with the addition of PG or WTR. The application of PG with NF at the rate of 10 t ha−1 recorded the highest microbial activity, soil available nutrients, grain yield and yield component of maize plants compared to the other treatments. Additions of NF+PG at the rates of 10 and 5 t ha−1 and F+WTR at 10 and 5 t ha−1 increased DHA by 1.70, 1.60, 1.40 and 1.20 times, respectively, compared to the NF treatment. It can be concluded that application of PG and WTR with the recommended application rates would help in improving the properties of heavy clay soils.

Impact of irrigation and fertilization regimes on greenhouse gas emissions from soil of mulching cultivated maize (Zea mays L.) field in the upper reaches of Yellow River, China

Greenhouse gas emissions from agricultural soil are strongly affected by the field practices including fertilization, irrigation and cultivation model. Understanding the mechanism of greenhouse gas emissions from soil and their impact factors is essential for cleaner agricultural production and global greenhouse gas mitigation. This paper investigated greenhouse gas emissions from soil of mulching cultivated maize (Zea mays L.) field under different irrigation and fertilization regimes. Border and drip irrigation with different schedules were implemented in the upper reaches of Yellow River, China. Border irrigation included three different irrigation depths (180, 315 and 450 mm), and drip irrigation was controlled by a tensiometer and triggered by three different matric potentials (−15, −25 and −35 kPa). Three nitrogen fertilizer levels (350, 250 and 150 kg ha−1) were applied for the drip irrigation triggered by the matric potential of −25 kPa. Soil acted as a sink of CH4 in the semiarid site regardless of irrigation and nitrogen fertilization regimes. Irrigation scheduling had no significant influence on CO2 emissions, but the irrigation method did have. Cumulative CO2 emissions increased by 24.7% for drip irrigation compared with border irrigation at the same water and nitrogen fertilizer levels. Cumulative CO2 emissions for the high nitrogen fertilizer treatment (350 kg ha−1) increased by 19.3% in comparison with the medium and low levels under drip irrigation. N2O emissions were positively related to the irrigation depth under both drip and border irrigation. Cumulative N2O emissions reduced by 23.5% for drip irrigation compared with border irrigation at the same water and nitrogen fertilizer levels. N2O emissions increased with the increase in nitrogen fertilizer application under drip irrigation. Drip irrigation with high frequency (−15 kPa) and medium nitrogen fertilization (250 kg ha−1) obtained the best economic and environmental performance through comprehensive evaluation of the yield, water and fertilizer productivity, global warming potential, greenhouse gas intensity and net ecosystem economic budget. The findings can provide an opportunity for greenhouse gas mitigation without crop yield reduction following the proper irrigation and fertilization regimes in the semiarid region.

Microbial community assembly and metabolic function during wheat straw decomposition under different nitrogen fertilization treatments

In-depth microbial community characterization, a community-level metabolic function analysis, and biogeochemical assessments of residues were performed to understand the principles governing microbial community assembly in wheat straw during decomposition with different N fertilization rates in soil. We identified a suite of decomposition-associated bacterial and fungal groups in straw that contribute to C and N cycling. The decomposition-associated microbial community in straw is likely mainly derived from the original straw, and the bacterial and fungal communities showed different patterns along with the decomposition. Overall, the microbial community composition and function were not substantially affected by the N fertilization rate, but N fertilization significantly increased the straw microbial assembly speed and had significant effects on the abundances of certain taxa and C- and N-related genes, leading to different decomposition rates of straw under different N fertilization rates. Furthermore, the straw quality, especially dissolved organic C (DOC) and lignin, accounted for most observed effects on microbial community development and decomposition. The results provide new insight into the roles of the microbial community in straw during crop residue decomposition for nutrient cycling in farmland ecosystems.

Phytoplankton community characteristics in rice paddy fields under different nitrogen fertiliser applications

Community characteristics of phytoplankton in the surface water of paddy fields under four nitrogen fertiliser (NF) treatments were studied in the Yangtze River Delta, China. The results were as follows: (1) in total, 65 species, belonging to six phytoplankton phyla and 50 genera were detected; their average total density was 1.25 × 106/L. Number of species and diversity of phytoplankton were higher in the control treatment (0 kg N/ha; CK) than in the NF treatments at later experimental times; (2) there was a significant positive correlation between phytoplankton density and total N; however, total density of phytoplankton was higher in CK than in NF treatments; (3) during the transplanting and rehabilitation stage, under high N treatments, phytoplankton mainly comprised Chlorophyta, among which the dominant species was Volvox aureus, while under low N treatments, the main phyla were Chlorophyta and Cryptophyta, with Chlamydomonas reinhardtii and Chroomonas acuta forming the dominant species. During the rice tillering stage, the dominance of Chlorophyta was partially replaced by Cryptophyta and Bacillariophyta in all NF treatments, while the proportion of Cyanobacteria in CK increased significantly; (4) species and density of Cyanobacteria were higher in CK than in NF treatments, accompanied by the dominance of nitrogen-fixing species such as Anabaena spp. at later experimental times. The results indicate that NF application changed the phytoplankton community. Low N conditions can promote competition for photosynthesis and nutrients among phytoplankton in paddy fields, while low N application rates can induce growth of some algae with nitrogen-fixing abilities.

Changes in stay-green and nitrogen use efficiency traits in historical set of winter barley cultivars

The objective of this study was to compare grain yield, nitrogen use efficiency (NUE) and stay-green traits in winter barley under low and high nitrogen (N) fertilization treatments. Field trials were conducted during two growing seasons in a southern Pannonian location (Novi Sad, Serbia) with fifteen six-rowed barley cultivars released between 1972 and 2013. The rate of genetic gain in grain yield was higher under high N level, indicating that modern barley cultivars use the applied N fertilizer more efficiently than older cultivars. The improvement in NUE and N uptake efficiency were positively related with year of cultivar release under both fertilization levels, while association between N utilization efficiency and year of cultivar release was significant at high N fertilization. Modern cultivars had higher normalized difference vegetation index (NDVI) values at the anthesis, start and mid senescence. Moreover, time to mid senescence was prolonged in modern cultivars, indicating slower N remobilization during early grain filling period. Values of NDVI at different senescence stages were more related to N uptake efficiency, while timing of senescence stages were in association with N utilization. Close association between NDVI values at different senescence stages and N uptake indicate that application of NDVI sensors could be used for identification of cultivars with improved N productivity.

Nitrogen Fertilizer Levels Affect the Growth and Quality Parameters of Astragalus mongolica.

Owing to overexploitation, wild resources of Astragalus mongolica, a Chinese herbal plant that is widely distributed in the arid and semi-arid areas of Northern China, have gradually become exhausted, and therefore, commercial cultivation is increasingly important to meet the growing demand for astragalus and reduce the pressure on wild populations. Nitrogen level is an important factor that affects the yield and quality of A. mongolica. However, uniform standards for fertilization among production areas have not yet been determined. In this study, the effect of nitrogen fertilizer treatment on the yield and quality of A. mongolica in the Qinghai-Tibet Plateau was explored using a control treatment (no added nitrogen, N0) and five different nutrient levels: 37.5 kg/ha (N1), 75 kg/ha (N2), 112.5 kg/ha (N3), 150 kg/ha (N4), and 187.5 kg/ha (N5). According to grey relational analysis, the optimal nitrogen fertilizer treatment was the N4 level followed by the N5 and N2 levels. Nitrogen fertilizer significantly increased the root biomass, plant height, root length, and root diameter. However, nitrogen fertilization had no significant effect on the content of Astragaloside IV and mullein isoflavone glucoside. The content of ononin and calycosin continually accumulated throughout the growing period. The results showed that the ononin and calycosin content under N4 and N2 is higher than other levels and there is not significantly different between different nitrogen fertilizer levels about them. The content of formononetin decreased gradually with the progression of the growing season. The optimal nitrogen fertilizer treatment for A. mongolica is recommended to be 150 kg/ha and the content of active compounds and yield were observed to reach the maximum in October.

Conversion of winter flooded rice paddy planting to rice-wheat rotation decreased methane emissions during the rice-growing seasons

To our knowledge, the conversion of winter flooded rice paddy (RF) to rice-wheat rotation (RW) has markedly decreased methane (CH4) emissions during the wheat-growing seasons. However, the effects of this conversion on CH4 emissions during the rice-growing seasons are unclear. To determine CH4 emissions during the rice-growing season and associated environmental factors under RF and RW systems, a split-plot design experiment was conducted in three RF fields in hilly areas of Sichuan province, China. One-half of each field was converted to RW, and the other half remained RF. Each plot of RW and RF was further divided into four subplots: three subplots for conventional nitrogen fertilization treatment (RW-CN and RF-CN) and one for unfertilized treatment (RW-NN and RF-NN). The study showed that the cumulative CH4 emissions from RW-CN during the rice-growing seasons were 192.77 ± 11.36 and 302.07 ± 28.34 kg C ha−1 in 2013 and 2014, respectively, which were decreased by 26.8% and 24.3% as compared to that from RF-CN. While for RW-NN, the cumulative CH4 emissions decreased by 54.1% and 24.0% as compared to that from RF-NN (372.49 ± 67.05 and 300.53 ± 13.49 kg C ha−1 in 2013 and 2014, respectively, P < 0.05). A higher Q10 (soil temperature sensitivity coefficient) of CH4 emissions during the whole experiment period was observed for RW-CN (6.69) than that for RF-CN (4.48). With rising soil temperature during the rice-growing seasons, the CH4 emissions for RW-CN escalated more rapidly than that for RF-CN. As expected, a positive correlation between CH4 fluxes and soil dissolved organic carbon (DOC) for both RF-CN and RW-CN was observed and DOC in RF-CN during the rice-growing seasons were higher than RW-CN. The soil dissolved inorganic nitrogen (DIN) was negatively correlated to CH4 emissions as the soil temperature ranged 22℃– 28℃. Moreover, rice yields in the RF-CN and RW-CN treatments were similar in both years of 2013 and 2014. These findings suggested that CH4 emissions were primarily controlled by soil environment, which was affected by water and fertilizer managements. The implication of this study is that the decreased CH4 emissions and increased crop yields could be achieved by conversion management from RF to RW.

Nitrogen Fertilizer Programs for Organic Flue-Cured Tobacco (Nicotiana Tabacum L.) Seedling Production

Certified organic flue-cured tobacco (Nicotiana tabacum L.) production has experienced significant expansion in the United States. Despite this expansion, there is very little information available that outlines organic nitrogen (N) programs for seedling production. To develop grower recommendations, research was conducted to evaluate the effects of a Peruvian seabird guano (SG), sodium nitrate (SN), or a combination of the two (SN_SG) in a float system on float water chemistry and seedling vigor. A conventional treatment (Conv; SQM Ultrasol Premium) was included for comparison. A greenhouse study was conducted twice between June 2016 and January 2017. Nitrogen fertilizer treatments were applied to tobacco float system water twice during the germination and growth of tobacco transplants. Float system water was collected every 5 days and analyzed for N forms, pH, dissolved oxygen, and bicarbonate. At the end of each experiment, transplant dimensions were measured and percent of usable plants collected. Float water bicarbonate concentration was &amp;lt;1 meq L−1 in treatments absent of SG for the duration of the study, but were in excess of 12 meq L−1 25 days after seeding (DAS) when SG was the exclusive N source. Despite high ammonium and bicarbonate concentrations with SG, neither factor negatively impacted seedling growth. Both SG and SN_SG produced as many usable plants as Conv; however, seedling height and diameter tended to be lower in SG compared to the other two treatments. No usable transplants were produced when SN was the sole fertility source, likely because of lack of nutrients other than N. Furthermore, many of the organic fertility products require biological activity to mineralize organic N to a plant-available form. This activity can have potentially detrimental outcomes on float system solution pH, dissolved oxygen, and bicarbonate levels.

Long-Term Tillage and Nitrogen Fertilization for Soybean on Gley Soil

During three years (2007, 2008 and 2009), multidisciplinary stationary research of reduced soil tillage and nitrogen fertilization was conducted for soybean [Glycine max (L.) Merr.], on Gley soil type of Croatian Baranya region. Research was carried out with four soil tillage treatments and three nitrogen fertilization level, set up as split-plot design in four repetitions. Tillage treatments (TT) were: CT- conventional tillage (autumn plowing 30 cm), DT- multiple disk-harrowing (autumn disk-harrowing 10-12 cm), LT- chiselling and disk-harrowing (autumn soil loosening 30 cm), NT- no-tillage. Nitrogen fertilization treatment (NF) for soybean was NF-1 = 35, NF-2 = 70, NF-3 = 110 kg N/ha. Weather conditions during the study were adverse with considerable aberrations, respectively significantly different from long-term mean. Thus, 2007 was extremely dry, 2008 was moderately humid and 2009 dry. Significant differences of soil water content (SWC) were identified in all years of research: NT had higher SWC in 2007 and 2008, while DT had hogher SWC in 2009 compared to CT. The yield was negatively statistically significant correlated with bulk density (BD), i.e. with increase of compaction yield decreased. Significant differences among years were recorded regarding soybean grain yield, whereas soil tillage systems showed following decreasing order, on average: CT (2.59 t/ha) &gt; LT (2.46 t/ha) &gt; NT (2.46 t/ha) &gt; DT (2.41 t/ha). Nitrogen fertilization on average did not influence soybean yield. On average, compared to CT, only DT had significantly lower soybean grain yield. The study showed a very successful application of reduced soil tillage systems in soybean production with the optimal nitrogen fertilization.

Reuse in the agro-industrial: Irrigation with treated slaughterhouse effluent in grass

Abstract The animal slaughter and meat processing industries generate large sources of effluents, rich in organic matter that can be used in plants irrigation as strategy in order to reuse water in agricultural properties. The objective of this work was to evaluate the production and the composition of coastcross grass for hay production by sprinkler irrigation with urea effluent treated by the anaerobic exercise. The experimental was developed in randomized blocks, with five treatments and four replicates (5 × 4), with time subplots. The five treatments used were: (i) T1 - irrigation with surface water plus 50.0 kg ha−1 cut−1 nitrogen fertilization (NF) provided as urea; (ii) T2, T3, T4 and T5 - irrigation with treated slaughterhouse effluent (TSE) plus 0, 16.5, 33.0 and 50 kg ha−1 cut−1 NF. The variables analyzed were the production of fresh and dry mass, soil chemical characteristics and prospective and bromatological analysis, during the winter and the summer. After the treatment, the effluent showed elevated concentration of total nitrogen (176.00 ± 52.32 mg L−1) and a low to moderate saline potential (EC = 1.46 ± 0.34dSm−1). In the winter the nutritional status and the coastcross grass production were kept by irrigation with the effluent, compared with the surface water treatment saving 100% of the nitrogen fertilization. The percentage of phosphorus, sodium and base saturation of the soil were altered by the wastewater. During the summer, the irrigation sludge with effluent were reduced due to rainfall inhalation, with less nutrients support. The higher precipitation occurrency at this season reduced the total amount of salt in the soil. The total production (winter and summer) of dry mass and fresh dough were superiors with the 100% NF treatments, regardless of the water source.

Nitrogen and chlorophyll status determination in durum wheat as influenced by fertilization and soil management: Preliminary results.

Handheld chlorophyll meters as Soil Plant Analysis Development (SPAD) have proven to be useful tools for rapid, no-destructive assessment of chlorophyll and nitrogen status in various crops. This method is used to diagnose the need of nitrogen fertilization to improve the efficiency of the agricultural system and to minimize nitrogen losses and deficiency. The objective of this study is to evaluate the effect of repeated conservative agriculture practices on the SPAD readings, leaves chlorophyll concentration and Nitrogen Nutrition Index (NNI) relationships in durum wheat under Mediterranean conditions. The experimental site is a part of a long-term-experiment established in 1994 and is still on-going where three tillage managements and three nitrogen fertilizer treatments were repeated in the same plots every year. We observed a linear relationship between the SPAD readings performed in the central and distal portion of the leaf (R2 = 0.96). In fertilized durum wheat, we found all positive exponential relationships between SPAD readings, chlorophyll leaves concentration (R2 = 0.85) and NNI (R2 = 0.89). In the unfertilized treatment, the SPAD has a good attitude to estimate leaves chlorophyll concentration (R2 = 0.74) and NNI (R2 = 0.77) only in crop grow a soil with relative high content of soil organic matter and nitrogen availability, as observed in the no tilled plots. The results show that the SPAD can be used for a correct assessment of chlorophyll and nitrogen status in durum wheat but also to evaluate indirectly the content of soil organic matter and nitrogen availability during different growth stages of the crop cycle.

Effects of Nitrogen Management on Soil Nitrogen Content and Rice Grain Yield in Double Cropping Rice Production Area with Continuous Full Amount of Straw Returning

ABSTRACTIn order to formulate a nitrogen (N) management strategy under continuous full amount of straw returning (CFSR) for double cropping rice production, long-term (2013–2016) paddy field experiments were conducted in double cropping rice production area in the Jiangxi province, China. Five N fertilizer treatments under CFSR were tested, that is, (i) no N fertilizer application (CK); (ii) conventional N fertilizer application (165kg N ha−1 and 195 kg N ha−1 in early and late rice variety with the ratio of basal dressing to topdressing as 6:4, respectively) (CNF6:4); (iii) recommended N fertilizer application (135 kg ha−1 N and 165 kg ha−1 N in early and late rice variety with the ratio of basal dressing to topdressing as 4:6, 6:4, and 8:2, respectively) (RNF4:6, RNF6:4, and RNF8:2). Nitrogen fertilizer treatments under CFSR had 5.70% and 8.93% higher soil total nitrogen (TN), 1.32% and 0.80% higher available nitrogen (AN), 16.55% and 22.94% higher NH4+-N, and 13.10% and 7.93% higher NO3--N than CK treatments in early and late rice variety, respectively. There were no differences in soil TN, AN, NH4+-N, and NO3--N contents between CNF6:4 and RNF6:4 treatments, while CNF6:4 treatment showed higher or significantly higher soil N contents than RNF4:6 and RNF8:2 treatments. N fertilizer treatment under CFSR showed 88.9% and 43.20% higher grain yield and 62.15% and 42.52% higher panicle numbers than CK treatments in early and late rice variety, respectively. Compared with CNF6:4, RNF treatments did not significantly reduce grain yield and yield components in early and late rice variety, respectively, except for RNF8:2. Compared with RNF6:4 and 8:2, RNF4:6 showed higher rice grain yield, while no obvious differences in yield components were obtained among all RNF treatments. We concluded that N fertilizer under CFSR was helpful to improve soil N contents and double rice grain yield and panicle numbers. Appropriate reduction of N application (18% and 15% reduction in early and late rice variety, respectively) on the basis of adjusting ratio of basal dressing to topdressing as 4:6 and 6:4 did not significantly reduce soil TN and double rice grain yield and yield components, especially, the 40% basal N dressing and 60% N topdressing was beneficial to increase double rice grain yield under CFSR.

Long-Term N Fertilization Decreased Diversity and Altered the Composition of Soil Bacterial and Archaeal Communities

Soil microbial communities are essential in the cycling of nutrients that affect crop production. Our goal was to characterize the microbial community structure following 34 years of nitrogen (N) fertilization treatments in continuous maize production in highly fertile soils. Using 16S rRNA gene-based analysis of the V4 region via Illumina HiSeq2500 technology with downstream bioinformatics processing and analysis with QIIME 2.0, we aimed to characterize the prokaryotic communities under three increasing N fertilization rates. Factor analyses indicated that a high N level decreased the diversity of soil bacterial and archaeal communities and altered the relative abundance (RA) of the dominant (&gt;1% RA) and minor (&lt;1% RA) phyla. Among the 12 major phyla, we determined increases in Gemmatimonadetes, Proteobacteria, and Euryarchaeota, accompanied by reductions in Cyanobacteria, Chloroflexi, Firmicutes, and Planctomycetes with increasing N. Within the 29 minor phyla, N fertilization led to increases in Aquificae, WPS2, Parvarchaeota, AD3, FCPU426, Armatimonadetes, TM7, Chlamydiae, and OD1, along with reductions of Nitrospirae, WS3, Tenericutes, Lentisphaerae, OP3, Synergistetes, Thermotogae, and prokaryotes that could not be reliably assigned to a phylum (classified as Other).

Towards Improving the Vegetative and Qualitative Traits of Sunflower Using Amending Soil (Zeolite and Manure Farmyard) under Water Deficit Stress

ABSTRACTThe effect of different sources of nitrogen fertilizers (organic fertilizers and urea) and zeolite under different irrigation regime on the qualitative traits of sunflower seeds was investigated by a trial, in 2014 and 2015 in Iran with split factorial on a randomized complete block design with three replications. Main plots consisted of irrigation regimes (irrigation after unloading 40%, 60% and 80% of available soil water (ASW)). The sub-plots consisted of factorial combinations of three nitrogen fertilizer treatments (100% organic, integrated treatment and 100% chemical treatment) and three levels of zeolite (10, 5 and 0 ton ha−1). Farmyard manure and urea were the organic and chemical sources of nitrogen, respectively; integrated treatment included 50% organic +50% chemical nitrogen. The percentage of nitrogen required by urea was set in a way that 100% of the required nitrogen could be provided by urea. The maximum diameter and stems height as well as the performance of the oil and protein by application of zeolite were measured in terms of the lack of stress in the first and second year, respectively. In sum, it can be concluded that the severe water stress can reduce the percentage of unsaturated fatty acids. In the first year, oleic acid and linoleic acid were decreased by 22% and 7%, respectively; while in the second year, they were reduced by 27% and 6.8%. Stearic acid also declined in the first and second years by 50% and 52%, respectively. However, an increase was observed for palmitic acid of sunflower. In both years, the application of organic fertilizer increased linoleic acid and oleic and improved the quality of sunflower seed oil. Under favorable irrigation conditions, organic fertilizers could be advantageous; while organic fertilizers and zeolite can be helpful under drought stress conditions.

Integrated use of straw mulch with nitrogen fertilizer improves soil functionality and soybean production

Mulching can effectively maintain and improve soil health and functionality. The mechanisms, however, have not been fully elucidated. Therefore, the effects of temperature on the biogeochemical properties of soil were investigated in the present study in relation to nitrogen management and soil functionality. The results of the 3-year field experiments showed that integrated straw mulch (S) and nitrogen fertilizer (N) treatments enhanced the activities of soil urease, invertase, alkaline phosphatase, and catalase by >1.8, 2.1, 2.0 and 1.4 fold, respectively, compared with the control treatment. Furthermore, these treatments increased soil available N by 28%, phosphorus by 45%, and potassium by 55%. In general, the soil organic carbon, dissolved carbon and labile organic carbon content in the treated plot were approximately 1.2–2.9 folds greater than in the control plot. These improvements in soil fertility and carbon indices increased the biomass and grain yield of soybean (67 and 75%, respectively) during the three-year study period. During 2015–2017, the straw mulch and nitrogen fertilizer treatment increased the soil moisture (23%) and decreased the soil temperature (8%) in comparison to the control in the 0–0.2 m soil depth and, therefore, improved soil enzyme activities, nutrient availability, and carbon stocks, and ultimately, soil functionality and sustainability, in the semiarid region.