Effects Of Nitrogen Fertilizer Application Research Articles

Analysis of Erect-Panicle Japonica Rice in Northern China: Yield, Quality Status, and Quality Improvement Directions.

China is the only country that extensively cultivates the indica and japonica rice varieties, with the largest japonica rice production area being in northeast China. A study of the relationship between the yield and quality of japonica rice and the effect of nitrogen fertilizer application on this relationship is important. In this paper, we aimed to assess the current yield and quality of japonica rice in northeast China. We selected erect-panicle varieties as the test materials. Field experiments were conducted using different nitrogen fertilizer levels for two consecutive years to analyze the rice varieties' yield, quality, interrelationship, and nitrogen fertilizer response. The average yield following high- and low-nitrogen treatments exceeded 10,000.00 kg/hm2, with a maximum of 12,285.63 kg/hm2. The high-yield-high-nitrogen treatment group had more panicles, a higher seed-setting rate, and a higher 1000-grain weight than the other groups. The high-yield-low-nitrogen group had a higher number of panicles and seed-setting rate than the other groups. The low-yield-high-nitrogen group had a lower number of whole grains, grain length-to-width ratio, and taste value than the other groups. The low-yield-low-nitrogen group had fewer primary branches than the other groups; excluding the primary branch-setting rate and 1000-grain weight, the values of the other panicle traits of the group were significantly higher than those of the other groups. The high-nitrogen-high-flavor group had lower panicle and spikelet numbers and higher spikelet fertility rates than the other groups. The low-nitrogen-high-flavor group had higher spikelet fertility rates and 1000-grain weight than the other groups. Compared to the other groups, the low-nitrogen-high-flavor group had a higher head rice yield, and the high-nitrogen-high-flavor group had a lower chalkiness rate. The main goal of the breeding and cultivation of high-yield and high-quality erect-panicle japonica rice in northern China is to achieve "dual high, dual low, and one high and one low" conditions, signifying a high yield with high or low nitrogen levels, low protein and amylose contents, high head rice rates, and low chalkiness. This study provides a new technique for enhancing the taste of northern erect-panicle japonica rice to promote the sustainable, high-yield, and high-quality development of japonica rice in northern China.

Effects of nitrogen fertilizer application on saline-alkali land cotton in China quantified using meta-analysis and regression analysis

Effects of nitrogen fertilizer application on saline-alkali land cotton in China quantified using meta-analysis and regression analysis

Nitrogen fertilizer amount has minimal effect on rhizosphere bacterial diversity during different growth stages of peanut.

The impact of short-term nitrogen fertilizer input on the structure and diversity of peanut rhizosphere microbiota (RM) at different growth stages (GSs) was explored in the southern paddy soil planting environment. Three levels of nitrogen were applied in the field: control (LN, 0 kg/hm2), medium nitrogen (MN, 55.68 kg/hm2), and high nitrogen (HN, 111.36 kg/hm2). The rhizosphere soil was collected during four GSs for high-throughput sequencing and chemical properties analysis. The effect of nitrogen fertilizer application on peanut RM was minimal and was obvious only at the seedling stage. In the four peanut GSs, a significant increase in relative abundance was observed for only one operational taxonomic unit (OTU) of Nitrospira under HN conditions at the seedling stage and mature stage, while there was no consistent change in other OTUs. The difference in RM among different peanut GSs was greater than that caused by the amount of nitrogen fertilizer. This may be due to the substantial differences in soil chemical properties (especially alkali-hydrolyzable nitrogen, pH, and available potassium or total potassium) among peanut GSs, as these significantly affected the RM structure. These results are of great value to facilitate deeper understanding of the effect of nitrogen fertilizer on peanut RM structure.

Combined Effect of Nitrogen Fertilizer Application and High Temperature on Grain Quality Properties of Cooked Rice.

Ambient temperature and nitrogen (N) fertilizer are two of the most important factors that affect rice grain quality. However, less information has been available on the interactive effect of N fertilizer and ambient temperature on grain quality under stressful high temperature (HT). In this article, the effects of panicle N fertilizer, ambient temperature, and their interaction on starch composition, particle size distribution of starch granules, starch physicochemical properties, and storage protein accumulation in milled grains were investigated to clarify the potential role of panicle N fertilizer topdressing in regulating rice grain quality under stressful HT by using a two-factor experiment of three N levels in combination with two temperature regimes. Results showed that appropriate application of panicle N fertilizer could attenuate the adverse effect of HT during grain filling on milling quality and chalky occurrence to some extent, particularly for the effective alleviation of HT-induced decrease in milling quality. However, the topdressing of panicle N fertilizer tended to enhance starch gelatinization enthalpy (ΔH) and its setback viscosity in HT-ripening grains, with the simultaneous decrements in the number and surface area proportions of smaller starch granules under the higher N fertilizer in combination with HT exposure. The effects of higher nitrogen fertilizer and HT exposure on total protein content and gluten composition of grains were additively increased. Hence, the topdressing of panicle N fertilizer exacerbated HT-induced deterioration in cooking and eating quality, rather than alleviating the negative impact of HT exposure on the palatability of cooked rice.

Distribution of phenolic compounds and antioxidant activities in layered grinding wheat flour and the regulation effect of nitrogen fertilizer application

<p id="C3">Clarifying the distribution of phenolic compounds in layered grinding wheat flour and its response to nitrogen fertilizer application would provide useful information for wheat quality improvement and high-quality cultivation. Two wheat cultivars, purple wheat (Jizi 439) and white wheat (Xinhuamai 818), were planted with two nitrogen application rate (HN, N 210 kg hm^-2; LN, N 105 kg hm^-2) in Zhengzhou and Yuanyang experimental sites during growing period in 2019 and 2020. The mature grains were ground into five milling fractionations (LY1, LY2 LY3, LY4, and LY5) from the bran layer to the endospermic layer by layered grinding, and the total phenolic content (TPC), the total flavonoids content (TFC), and the anthocyanin content (AC), and their antioxidant activity were determined. The results showed that the TPC, TFC, AC, and antioxidant activity (TEAC, FRAP) in free phenols and conjugated phenols extracts decreased from the outer layer flour fractionation to the inner layer flour fractionation. The purple wheat, named as Jizi 439, had a higher antioxidant content and antioxidant activity than white wheat (Xinhuamai 818), but the difference between the two cultivars displayed a decreasing trend from the bran layer flour fractionation to endosperm layer flour fractionation. The TPC, TFC, and AC of LY1 to LY3 flour fractionation increased with the increase of nitrogen fertilizer application except for TPC of LY1 in Yuanyang. However, the contents of total phenolics and total flavonoids of LY4 to LY5 flour fractionation had a weak response to nitrogen fertilizer application. The content of ferulic acid accounted for more than 93% of the TPC in wheat grains and had a higher value under low nitrogen condition. In conclusion, purple wheat had higher antioxidant substances such as phenolics than white wheat, and the difference between purple wheat and white wheat decreased with the deepening of grinding degree. The content and activity of antioxidants in the outer layer flour fractionation were significantly responsive to nitrogen regulation, and the content increased with the increase of nitrogen.

ANALISIS HUBUNGAN TINDAK AGRONOMI DAN SIFAT KIMIA TANAH TERHADAP PRODUKTIVITAS DAN MINYAK ATSIRI BUNGA MELATI DI KABUPATEN BANJAR

Banjar Regency in South Kalimantan is the center of jasmine production. The productivity level of the province of South Kalimantan cannot make a large contribution to national jasmine production because the harvested area of South Kalimantan is less competitive than Central Java, this is unforgettable because there are differences in agronomic actions and soil chemical properties. This study analyzed the relationship of agronomic actions and soil chemical properties and the dominant traits affecting the productivity of jasmine in the Banjar Regency. This study adopted survey methods and field observations.The survey method included determining the sampling locations and interviews with jasmine farmers. The selected villages were determined by purposive sampling method by deliberately choosing villages that were dominant in cultivating jasmine plants, namely Labuan Tabu village, Jingah Habang Ilir village, and Pandak Daun village. The results revealed that the agronomy action and soil chemical properties simultaneously had A significant effect on the yield of jasmine. Each of the treatments of nitrogen application, potassium application, and pruning frequency significantly affected the yield of jasmine. The dominant agronomic actions on the yield of jasmine were nitrogen application, pruning frequency, and potassium application, with the contribution of 46.51%, 17.72%, and 17.14%, respectively. The indirect effect of nitrogen fertilizer application channeled through the pruning frequency contributed 18.19% higher than the direct effect of the pruning frequency alone. The indirect effect of potassium fertilizer application through the pruning frequency contributed 16.33% to the jasmine productivity. The application of N fertilizer and the pruning frequency showed a very significant and positive linear relationship to productivity with regression equations of 5.173+0.01526 N and –0.194+3.587 Fpks, respectively.

A REVIEW: EFFECTS OF NITROGENOUS FERTILIZERS ON SOIL (PH, MICROBIAL COMMUNITY, GREENHOUSE GASES EMISSION AND CARBON POOL)

With world population increasing at such fast rate and land available to cultivate decreasing substantially, it is of prime need to increase the productivity. This is the reason of increasing use of fertilizer in the world especially N fertilizer because of its direct influence on growth attributes. The main objective of this article is to review the existing literature regarding the effect of nitrogen fertilizer application in soil pH, microbial community, soil carbon pool and emission of Green House Gases. Most researches have shown urea to be the major source of anthropogenic N addition to soil. Studies have concluded that the unmanaged application of N fertilizers in excess amount than what crops utilize is the nerve center favoring pH change. In regards to their impact in microbial community, previous land management practice seemed pivotal. Also, abundance and diversity of greater fraction of microbes (fungi and bacteria) narrowed down with intensified application in cultivated soils in majority of trails studied. Increased efflux of CO2 and N2O was observed in soil fertilized with N however, CH4 emission was limited as methanotrophs were replaced with nitrifiers. Acid rain was highly favored with such emissions. No changes in soil organic carbon pool were seen in short period but in due course of time, decomposition or turnover rate decreased increasing the stability of carbon under lignin rich root residues. Therefore, alterations varying with depth have been noticed in soils treated with N due to mineral association.

Effect of Nitrogen Fertilizer Applications on Nitrogen Remobilization and Grain Yield in Soybean (Glycine max [L] Merril) in the Savelugu-Nanton Municipality in Northern Region of Ghana

Two experiments were conducted in the Savelugu-Nanton Municipality of the Northern Region of Ghana in 2012 and 2013 to assess the effect of N fertilizer on growth, N remobilization and grain yield of three local varieties of soybean (Glycine max [L] Merill). The experiments were a 3 x 4 factorial laid in Randomized Complete Block Design (RCBD) with four replications. Factor A was soybean varieties (Jenguma, Quarshie, Ahotor); Factor B was 0, 15, 30 and 45 kg N ha-1. The experimental fields were planted manually on the flat by drilling and later thinned to 2 plants hill-1 at 0.50 m × 0.10 m with a population of about 400 000 plants ha-1. Growth and yield parameters measured were plant height, nodule number plant-1, nodule dry weight plant-1, percent nodule effectiveness, number of pods plant-1, number of seeds pod-1, 100 seed weight, harvest index and grain yield. The results showed that the control recorded lower figures in all growth parameters. Nitrogen remobilization was also observed in all plots, which indicate that soybean needs greater levels of N during grain filling. Again, N remobilization and soybean yield were highest in the 45 kg N ha-1 treatment compared to the other treatments. However, considering the overall yields, farmers in the study area should be advised to adopt starter N fertilization of soybean for higher yields as the soils are highly degraded in soil fertility.

Nitrogen fertilizer application rate impacts eating and cooking quality of rice after storage.

The effect of nitrogen fertilizer application on the quality of rice post-storage is not well understood. The eating and cooking quality (ECQ) of rice treated with 0 (CK, control), 160 (IN, insufficient nitrogen), 260 (AN, adequate nitrogen), and 420 (EN, excessive nitrogen) kg N/ha was analyzed over 12 months of storage. Results showed that the rate of nitrogen fertilizer application had no significant impact on the changes in taste value during storage. However, EN application significantly increased the hardness (p < 0.05), reduced the gumminess (p < 0.05), and delayed the decline in the viscosity of rice paste by two months after one-year storage, compared with other treatments. In conclusion, although EN application resulted in an inferior texture of rice, it delayed the quality change by two months during storage. It was demonstrated that a rational nitrogen application rate (0-260 kg N/ha) for rice cultivation is particularly important to obtain high ECQ; however, EN may be beneficial for the stability of the ECQ during storage.

Components of the Production and Chemical Composition of Safflower Seeds as a Function of Nitrogen Fertilization

Aims: The objective of this study was to evaluate the effects of nitrogen fertilizer application on the direct and indirect productive components of safflower.&#x0D; Study Design: The treatments were arranged in randomized blocks, with four replicates, and consisted of five doses of nitrogen (N): 0, 50, 100, 150 and 200 kg.ha-1, in the form of urea (45% N), which was manually incorporated into the soil 30 days after plant emergence.&#x0D; Place and Duration of Study: Sowing was carried out under field conditions on a small rural property in the municipality of Toledo-PR, Brazil. The experiment was conducted in between May and October 2018, totaling 158 days.&#x0D; Methodology: Morphometric parameters were evaluated at the full flowering stage, and the yield and chemical composition of the achenes were assessed during physiological maturation of the plants. Data were analyzed using analysis of variance (ANOVA) at the 5% significance level. Regression equations were fitted to the means of the quantitative variables.&#x0D; Results: The results showed that safflower grain yield was strongly influenced by the application of N-urea, with the maximum yield at a dose of 120 kg.ha-1 N. A joint analysis of the regression equation for N-urea application and grain yield, and the prices of N and safflower grains used, revealed that the most economical dose was 70 kg.ha-1 N, which provided the maximum profit per unit area. There was a positive linear correlation between grain yield and protein content (r = 0.51). Stem diameter, aerial dry biomass, grain yield, number of branches, and floral chapters per plant increased with N application, indicating that safflower culture responds positively to nitrogen fertilization.&#x0D; Conclusion: We conclude that sustainable use of nitrogen fertilizer using the maximum economic efficiency dose, can contribute to better plant health and, at the same time, reduce production costs.

Evaluating the potential health and economic effects of nitrogen fertilizer application in grain production systems of China

In past decades, large amounts of N fertilizers have been applied in agricultural production of China. N fertilizer has not only underpinned food production but also led to great concerns about negative environmental impacts. We used a life cycle assessment (LCA) approach to assess nitrogen fertilizer induced potential human health risk (HHR) and human capital loss (HCL) of rice, wheat and maize production systems. We found that the HHR of rice, wheat and maize was 633004, 264105 and 418644 DALY/yr, respectively. The rice production system caused the highest potential risk while the wheat production system the lowest. Fine particulate matter formation (FPMF) was the most serious health risk index, and accounted for nearly 87% of HHR. Sown area and crop type both play an important role in HHR. The potential loss of human capital caused by rice, wheat and maize production are 37.5, 15.6 and 24.8 billion RMB/yr, respectively. The total HCL accounted for about 5.9% of the Chinese grain yield value in 2017. We constructed 3 scenarios to evaluate the potential for reduction of human health risk. In scenario A, reducing N fertilizer rates to an appropriate level, the HHR decreased by about 23%, while in scenario B, enhancing nitrogen use efficiency and production technology, decreased HHR by about 22%. Furthermore, when we combined both scenario A and B, the HHR was reduced by as much as 37%. Improving fertilizer management practices in grain production in China has a great potential to reduce adverse impacts on human health, and more attention should also be paid to the impacts of air pollutant emissions from agricultural production on human health.

The Influence of Nitrogen Fertilizer Application on Yields and Nitrogen Use Efficiencies of &amp;lt;i&amp;gt;Solanum macrocarpon&amp;lt;/i&amp;gt; and &amp;lt;i&amp;gt;Solanum scabrum&amp;lt;/i&amp;gt; in Southwest Nigeria

Solanum macrocarpon and Solanum scabrum are good sources of vitamin, minerals, protein, anti-oxidants and fiber in southwest Nigeria. The study examined the effects of nitrogen fertilizer application on yields and nitrogen use efficiencies of Solanum macrocarpon and Solanum scabrum in Iwaro-Oka, Ondo State in southwest Nigeria in 2014 and 2015. The experiment was a 4 × 4 factorial arranged into a randomized complete block design with four rates of urea-N drilled at 0, 40, 80 and 160 kg/ha and replicated four times. Each plot was 3 m × 2 m with space of 1 m between plots. Vegetable seeds were planted by drilling. Fresh shoot and dry matter yields were determined. Nitrogen content and uptake were determined, and nitrogen use efficiency estimated. The result showed that average dry matter weight for S. macrocarpon was 228 kg/ha and S. scabrum was 6116 kg/ha. Average nitrogen uptake was 5.90 kg/h and 158.60 kg/ha for S. macrocarpon and S. scabrum, respectively. Nitrogen use efficiencies were 6.48 kg/ha, 0.15 kg/ha and 0.1 kg/ha for S. macrocarpon and 87.33 kg/ha, 26.14 kg/ha and 24.35 kg/ha for S. scabrum at 40, 80 and 160 kg N/ha, respectively. Negative values were obtained for N-recovery for S. macrocarpon while S. scabrum gave 5.85%, 2.10% and 1.44% at 40, 80 and 160 kg N/ha, respectively. The study concluded that S. scabrum had higher nitrogen use efficiency in the soil than S. macrocarpon and that highest NUE and N recovery were obtained at 40 kg N/ha.

Effects of Different Level of Nitrogen Fertilizer Application on Growth, Yield, Quality and Storage Life of Onion (Allium cepa L.) at Jimma, South Western Ethiopia

Onion (Allium cepa L.) is one of the most important vegetable crops produced in Ethiopia. Yield and productivity of the crop has been far below the regional and national standards owing to several factors; absence of location specific fertilizer recommendation being the major among others. In Ethiopia, post harvest loss of vegetables contributed up to 30% yield reduction. Thus, a field experiment was conducted at Jimma University College of Agriculture and Veterinary Medicine Research field during dry season to study the effects of Nitrogen fertilizer application on growth, yield, quality and storage life of irrigated onion under Jimma condition, South Western Ethiopia. The treatments consisted of four levels of Nitrogen (0, 50, 100 and 150 kg N ha -1 ) that laid out in Randomized Complete Block Design with three replications. Data on growth, yield, bulb quality and storage life parameters were recorded and analyzed using GenStat 12.1 version computer soft ware packages. Results of the study revealed that; Nitrogen fertilizer applications had shown a highly significant effect on growth, yield and quality of onion. Similarly, the keeping qualities of the Onion bulbs are highly influenced by application of N at different levels. Excessive application of Nitrogen fertilizer caused higher bulb rots (%); bulb sprouts (%) and weight loss (%) during the three month storage time at ambient temperature. This can be recommended for use by potential onion investors or farmers in the study area. Keywords : Growth, Nitrogen, Onion, Quality, Storage life, Yield. DOI : 10.7176/JNSR/9-10-05 Publication date :May 31 st 2019

Effect of Nitrogen Fertiliser Application on Maize Yield Across Agro-Ecological Regions and Soil Types in Zimbabwe: A Meta-analysis Approach

Accurate nitrogen (N) fertilisation increases crop yields and minimises environmental pollution in maize based production systems. In this study we report on a meta-analysis of the effects of N fertilisation on maize yield using observations from 53 studies conducted in Zimbabwe since the 1950s for possible refinement of fertiliser recommendations. We assessed the response of maize to: 100 kgN ha−1 compared to the control using the weighted mean yield difference approach. Application of N fertiliser significantly (p 100 kgN ha−1 (> 1.5 fold of recommended blanket rate) in mineral form in loam soils under good management in areas that receive 600–1000 mm year−1 rainfall whilst rates of < 30 kgN ha−1 (< 50% of recommended rate) can be relied upon for positive yield response in small holder areas that receive < 600 mm rainfall year−1.

Response of Nitrogen Losses to Excessive Nitrogen Fertilizer Application in Intensive Greenhouse Vegetable Production

Excessive nitrogen fertilizer application in greenhouse vegetable production (GVP) is of scientific and public concern because of its significance to international environmental sustainability. We conducted a meta-analysis using 1174 paired observations from 69 publications on the effects of nitrogen fertilizer application and reducing nitrogen fertilizer application on the nitrogen losses on a broad scale. We found that the increase in nitrogen loss is much higher than that in production gain caused by excessive application of nitrogen fertilizer: nitrate leaching (+187.5%), ammonium leaching (+28.1%), total nitrogen leaching (+217.0%), nitrous oxide emission (+202.0%), ammonia emission (+176.4%), nitric oxide emission (+543.3%), yield (+35.7%) and nitrogen uptake (+24.5%). Environmental variables respond nonlinearly to nitrogen fertilizer application, with severe nitrate leaching and nitrous oxide emission when the application rate exceeds 570 kg N/ha and 733 kg/N, respectively. The effect of nitrogen fertilizer on yield growth decreases when the application rate exceeds 302 kg N/ha. Appropriate reduction in nitrogen fertilizer application rate substantially mitigates the environmental cost, for example, decreasing nitrate leaching (−32.4%), ammonium leaching (−6.5%), total nitrogen leaching (−37.3%), ammonia emission (−28.4%), nitrous oxide emission (−38.6%) and nitric oxide emission (−8.0%), while it has no significant effect on the nitrogen uptake and yield.

Effects of Nitrogen and Plant Density on Maize (Zea mays L.) Phenology and Grain Yield

Nitrogen fertilizer and plant density are considered some of the most important factors affecting phenology and grain yield of maize. Therefore, current study was conducted to assess the effects of nitrogen fertilizer application and plant density on phenology (days to tasseling, silking and maturity) and grain yield of maize (Variety: Rampur Composite) at Mangalpur VDC-3, Anandapur, Chitwan, Nepal during 2006-07 winter season. The five levels of nitrogen as 0, 50, 100, 150 and 200 kg N/ha and three levels of the plant population as 55555, 66666 and 83333 plants/ha were evaluated using two factorial randomized complete block design with three replications. The days of flowering (tasseling and silking) decreased with increasing nitrogen level up to 200 kg N/ha and increased with increasing level of plant population up to 83333 plants/ha). Physiological maturity and grain yield increased with increasing level of nitrogen up to 200 kg N/ha and plant population up to 83333 plants/ha. The highest grain yield (6925.79 kg/ha) was obtained with 200 kg N/ha + 66666 plants/ha. This study suggested that maize production can be maximized by cultivating maize with the use of 200 kg N/ha and maintaining the plant density of 66666 plants/ha.

Effects of nitrogen fertilizer application on carbon dioxide emissions from soils with different inorganic carbon contents.

The application of nitrogen (N) fertilizer results in decreases of soil pH, but its effects on CO2 emission from soils with different inorganic carbon contents remain unclear. An closed-jar incubation experiment was conducted to examine the effects of N fertilizer and nitrification inhibitor (DCD) on soil pH and CO2 emissions from three soil types with different contents of soil inorganic carbon (SIC), including paddy soil (PS), lime concretion black soil (CS), and eum-orthic anthrosols (AS). There were three treatments for each soil type, including control (N0), 0.2 g·kg-1 N fertilizer (N0.2), and its combination with DCD (N0.2+DCD). Soil pH, contents of mineral N (NH4+, NO3-), and CO2 emissions were measured. The results showed that N fertilizer addition significantly reduced soil pH and increased soil CO2 cumulative emissions in each type of soil. Compared to control, the CO2 cumulative emissions after 49 days incubation from the three soil types were enhanced by 39.4%, 23.4%, and 71.8% for PS, CS, AS soils, respectively. The soil pH of N0.2+DCD for three soil types were significantly higher than N0.2 after 49 days incubation, indicating that DCD application inhibited soil nitrification process. There were no significant differences in the mean CO2 cumulative emissions of PS and CS soils between N0.2 and N0.2+DCD treatments; however, N0.2+DCD treatment significantly reduced cumulative CO2 emissions from AS soil by 12.5%. Soil inorganic carbon can effectively buffer soil acidification caused by N fertilizer addition. The CO2 emission in calcareous soil following N addition is not only derived from the mineralization of soil organic carbon, but also from the dissolution of inorganic carbon. Given the large differences in soil inorganic carbon content in different regions of China, the problem of soil acidification and soil inorganic carbon pool consumption caused by long-term large amount of N fertilizer inputs deserve more attention.

窒素施肥と収穫時期が稲発酵粗飼料用品種「たちすずか」の材料草およびサイレージの化学成分と発酵品質に及ぼす影響

窒素施肥と収穫時期が稲発酵粗飼料用品種「たちすずか」の材料草およびサイレージの化学成分と発酵品質に及ぼす影響

Effect of Nitrogen Fertilizer Application on Corn Residue Decomposition in Iowa

Core Ideas Application of 32% urea ammonium nitrate after harvest has no effect on residue decomposition. Three months after N addition, 54 to 69% of residue remained with no N rate differences. The remaining amount of residue after 12 mo was 35 to 49% across all N treatments. Incubation study shows soil temperature as a major factor in residue decomposition. Nitrogen addition suppressed CO2–C evolution during residue incubation. Corn (Zea mays L.) residue is one of the sources of soil organic carbon (SOC) in row cropping systems in the Midwest. Farmers in Iowa apply liquid N to corn residue after harvest, assuming it will increase corn residue decomposition. The objective of this study was to investigate the effectiveness of N application for increasing corn residue decomposition. The study included two fields with three N rates (0, 34, or 67 kg N ha−1) of liquid 32% urea ammonium nitrate (UAN) applied after harvest, and two laboratory incubation experiments with three temperatures (0, 25, and 35°C) in 2012 and 2013. The experiment design was a randomized complete block in four replications in a no‐tillage system (NT). The average mass of residue organic carbon (OC) after harvest was in the range of 1.6 to 1.7 Mg ha−1. Residue OC in the field declined sharply in both years, particularly during the first 3 mo, with no significant difference between N treatments. The only difference in field residue decomposition occurred after 6 mo (P = 0.0241) at the Olson location in 2012, where a greater (&gt;21%) amount of remaining OC was associated with 0 kg N ha−1 than with other N treatments. The incubation study showed an increasing rate of residue decomposition with increasing soil temperature with no N application effects on residue decomposition. These findings show that air and soil temperatures are the driving force for residue decomposition, especially at 25°C, rather than with N addition.

Econometric Analysis of Effects of Nitrogenous Fertilizer Usage on Tomato Yield in Tokat, Turkey

This study aims to investigate the effects of nitrogen fertilizer application on tomato yield by using econometric models. The data obtained by questionnaire from 53 farmers who produce tomatoes in Tokat province constitute the main material of the study. The Simple Random Sampling Method was used to determine the sample size with a 90% confidence interval and 10% margin of error. Nine models were tried to determine the best model to explain the effect of nitrogenous fertilizer usage in tomato cultivation. The data in the models were used to calculate the growers’ optimal fertilizer amount of use (physical optimum and economical optimum values were calculated) and the results were compared to the ones suggested by the experts. As a result, through the statistical studies, quadratic model was found to be the most suitable one. It has been determined that tomato farmers use less (10.54 kg da-1) or excess (23.48 kg da-1) N fertilizer than the level at which economic optimum is achieved.