Differences In Nitrogen Levels Research Articles

Nitrogen retention capacity of paddy soil improved under long-term garlic-rice rotation

ABSTRACT Although significant differences in soil nitrogen levels exist under different paddy-upland rotations, the main reason for this is unclear. The nitrogen retention capacity and loss of ammonia volatilisation, leaching, etc. of paddy soil with large differences in nitrogen levels from two long-term rotations, garlic-rice and wheat-rice, were measured using the soil column simulation method. The results showed that the loss rate of leaching was only 5.4%, whereas that of ammonia volatilisation was up to 22.8%, which was the main nitrogen loss way of paddy soil under the two rotations. The average ammonia volatilisation rates under wheat-rice rotation with high and low nitrogen application rates were 12.1% and 40.2% higher than that under garlic-rice rotation, leading to a decrease in the total nitrogen loss amount and rate through ammonia volatilisation by 29.8% and 8.8%, respectively. As a result, nitrogen retention in the soil under garlic-rice rotation increased by 12.7%. In conclusion, the long-term garlic-rice rotation could significantly inhibit ammonia volatilisation, thus improving the soil nitrogen retention capacity. The straw return may increase soil organic matter content, reduce ammonia volatilisation loss, and enhance soil nitrogen retention capacity and productivity.

Growth, photosynthesis, and nutrient uptake in wheat are affected by differences in nitrogen levels and forms and potassium supply

Nitrogen (N) and potassium (K) are essential macronutrients for plants growth; however, the mechanism by which K mediates negative effects on ammonium-sensitive plants is still poorly understood. We hypothesized that K supplies may enhance antagonistic ammonium stress while improving nitrate nutrition function, which wheat seedlings were grown in sand culture in the presence of two N forms (ammonium; nitrate) supplied at two rates (2, 10 mmol L−1) and three K levels (0.5, 5, 15 mmol L−1). We found that a high N rate increased plant biomass under nitrate nutrition, while it had a negative effect under ammonium nutrition. Compared with nitrate, biomass was depressed by 54% or 85% for low or high N rate under ammonium. This resulted in a reduction in gas exchange parameters and a subsequent decrease in growth variables and nutrient uptake, whereas these parameters increased significantly with increasing K levels. Moreover, in principal components analysis, these variations were highly clustered under nitrate nutrition and highly separated under ammonium nutrition. Our study shows a clear positive interaction between K and N, suggesting that high K supply relieves ammonium stress while improving growth vigor under nitrate nutrition by enhancing nutrient uptake and assimilate production in wheat plants.

Response of the copro-necrophagous beetle (Coleoptera: Scarabaeinae) assemblage to a range of soil characteristics and livestock management in a tropical landscape

Understanding changes in copro-necrophagous beetle diversity related to characteristics of habitat and soil associated with livestock management systems can provide a tool for the conservation of edaphic fauna and improved use of natural resources. We evaluated changes in species diversity and assemblage structure in copro-necrophagous beetles under different livestock management systems in an anthropized tropical dry forest landscape in Mexico. We used a standard sampling protocol to capture copro-necrophagous beetles in three livestock management systems: silvopastoral systems with Guazuma ulmifolia Lam. (SPS) associated with grasses, treeless pastures (monocultures) and managed tree fallows of tropical dry forest with livestock. We characterized the habitat structure, management practices and physico-chemical parameters of the soil in each system. We recorded a total of 1423 specimens belonging to 15 species. The results show a greater beetle species richness in the SPS with G. ulmifolia, which declines with reduced site complexity and soil quality and increased management practice intensity. There was a positive relationship between beetle species abundance and the soil physico-chemical characteristics such as moisture and nutrient content, as well as with the density of plants. A negative effect of management practices (use of insecticides, anti-parasite treatments and burning) was observed on beetle abundance; when the analyzed variables were related to each individual species, only four species responded to differences in levels of nitrogen and magnesium, as well as to the management practice and density of plants. Systems where perennial woody plants (trees and/or shrubs) interact with traditional components (animals and herbaceous forage plants) under integrated management can provide favorable conditions for the maintenance of a relatively high diversity of beetle species as well as a refuge for species with different habitat requirements.

Effect of Pseudomonas aureofaiciens & Pseudomonas putida on growth of sorghum biocolor and protect them from infection of Rhizoctonia solani fungi

The activity of two bacteria isolates Pseudomonas aureofaiciens & Pseudomonas putida in improving some specific and quantitative characters of Sorghum biocolor and protecting the plant from infection with the fungus Rhizoctonia solani was studied. Complete Randomized Design with three replicates was used in this experiment. The results showed significant higher values of treatments with bacterial isolates in growth percentage, leaf area, height of plant, chlorophyll content and dry weight of shoots. The results also showed significant differences in levels of nitrogen and phosphorus in shoot weight of plant for all treatments which treated with bacterial vaccines. The isolates also improved the studied characters of plants cultured in soil contaminated with Rhizoctonia solani and significantly inhibited the effect of plant pathogen. We concluded from this research it can use bacterial vaccines as new biological technique in improving Agricultural production as Biofertilizers and Biocontrol to inhibit fungi growth on crops.

Element content of propolis from different regions of Turkey

Levels of Na, K, Ca, Mg, N, Cu and Zn of propolis samples originating from different geographic locations of Turkey were investigated. Sodium was the most abundant element in the samples. The calcium content was found between 0.118-0.0793 mg g-1. The highest magnesium content was found in samples from Yozgat region, whereas the lowest was in those of Adana region. Potassium content changed between 0.121-0.364 mg g-1. There were no statistical differences in nitrogen levels. Interestingly, no sulphur (S) was detected in propolis samples. The copper and zinc content changed between 0.045-0.096 mg g-1, 0.176-0.676 mg g-1, respectively. Finally, mineral content of Turkish propolis was about the same as the commercial propolises from other countries. The content of Cu in propolises was generally within safe limits, and compared well with levels in foods from Turkish Food Codex, though Zn contents were high.

Greywater treatment with the submergent Triglochin huegelii—a comparison between surface and subsurface systems

Initial studies using Triglochin huegelii, a Western Australian species, in wastewater treatment experiments have shown that Triglochin has consistently removed more nitrogen and phosphorus, in all parts of the plant leaves, tubers and roots, than most other indigenous emergent macrophyte species. Our recent results have again shown that these types of plants do effectively assimilate nutrients from greywater. There was an increase in total N and total P in biomass measurements of T. huegelii leaves, roots and tubers during the course of the investigation. Sixteen percent of the greywater input N and 3% of input phosphorus was incorporated in plant tissue. Two further experiments were conducted using different environmental conditions for the plants. A comparison was made between root zone and complete pond conditions, with loading rate and retention times both doubled in some tanks. We found that more nutrients were absorbed by the plants in the pond system, with greater differences in nitrogen levels in the leaves (×2) than in under-ground roots and tubers (×1.6). Plants in ponds with the highest nutrient loading (10 l tanks) demonstrated the greatest growth and nitrogen gain, while tanks having the longest retention time (5 l tanks) had proportionally more N and P retention.

Spatial variability of nitrate nitrogen in soil during the growing season of maize, cowpea and soybean

The nitrogen advantage of legumes in crop rotation systems is well known, but the nitrogen advantage from legumes to associated crops in an intercropping system is unclear. The objective of this study was to determine whether plant-available nitrogen is released by cowpea and soybean during the growing season, since this could mean a saving in nitrogen fertilizer for an associated crop in an intercropping system. Nitrate nitrogen levels were monitored monthly throughout two growing seasons on cowpea, soybean and maize plots at two localities. There was no evidence of nitrogen enrichment of soil by the legumes in the early growing stages, but nitrogen was released into the soil when the legumes reached maturity, about four months after planting. The nitrogen enrichment of the soil occurred only within the legume rows, since no differences in nitrogen levels were found between the rows. This suggests that the mechanism of nitrogen enrichment of soil from these legumes is the rapid mineralization of nitrogen from roots and/or nodules when they reach maturity. It is, therefore, unlikely that legumes can provide a nitrogen advantage to associated crops within an intercropping system in the same season.

「加賀太」キュウリ（Ｃｕｃｕｍｉｓ ｓａｔｉｖｕｓ Ｌ．ｃｖ．Ｋａｇａｆｕｔｏｋｙｕｒｉ）の葉および果実における苦味発現と窒素代謝との関連

苦味のない高品質の'加賀太'キュウリの栽培体系を確立するために, 苦味の発現と窒素代謝との関係について検討した.1. 自根苗の無苦味系統株と苦味系統株の葉における全窒素含有率, 硝酸イオンとアミノ酸態窒素含有率の比較を行った.その結果, 苦味系統株の方が無苦味系統株より, 苦味果の発生率は高く, 茎長, 葉重, 根重は大きかったが, 葉色には差がなかった.葉中の全窒素含有率, アミノ酸態窒素含有率は, 苦味系統株の方が無苦味系統株より高かったが, 硝酸イオン含有率は低かった.2. 接ぎ木苗の苦味を有する上位葉あるいは果実と苦味を有しない下位葉あるいは果実とにおける全窒素含有率, 硝酸イオンとアミノ酸態窒素含有率の比較を行った.その結果, 葉の苦味は上位葉が下位葉より強く, 全窒素含有率, アミノ酸態窒素含有率は高く, 硝酸イオン含有率は低かった.また, 苦味果では無苦味果よりも, 全窒素含有率, 硝酸イオンとアミノ酸態窒素含有率のいずれも高かった.以上の結果, 苦味果の発生する株の葉, 苦味を有する葉および苦味果では, 苦味のないものに比べて, 窒素代謝が活発であり, それに伴ってククルビタシンCの生合成も促進されるために, 苦味が強く発現するものと考えられる.

Mistletoe host‐resemblance: A study of herbivory, nitrogen and moisture in two Australian mistletoes and their host trees

Abstract For 150 years mistletoe host‐resemblance has been an unsolved puzzle. Mimicry, camouflage, host protection and shape modification by the host tree have all been advanced as possible solutions. No extended examination of herbivory of host‐parasite pairs has ever been done, however, to put these explanations to the test. The study was carried out in northeastern Australia from March to July 1994. Rates of leaf herbivory were estimated for seven individuals of Amyema biniflora Barlow (a cryptic mistletoe species), Dendrophthoe glabrescens (Blakely) Barlow (a non‐cryptic mistletoe species) and their host trees (Eucalyptus tessellaris F. Muell. and Eucalyptus platyphylla F. Muell., respectively). In addition three measures of leaf palatability–nitrogen content, moisture content and toughness–were also assessed. Variability in mistletoe leaf shape was quantified by measuring the leaf widths of mistletoes on a variety of host tree species. Mistletoes sustained greater levels of herbivory compared to their host trees, but herbivory did not differ between mistletoe species. The non‐cryptic mistletoe had lower levels of nitrogen compared to its host tree, but there was no difference in nitrogen levels between the cryptic mistletoe and its host. The moisture content of mistletoe leaves was greater than that of their hosts but not between mistletoe or host species. The mistletoe species had tougher leaves than their host trees. Leaf shape was different for one species of mistletoe growing on different host trees, but constant for another species of mistletoe. The results contradict, in some crucial aspect, all of the mimicry hypotheses currently on offer.

Patchiness in semi‐arid dwarf shrublands: Evidence from satellite‐derived indices for elevated CO2 assimilation rates on a geochemical mound in the Karoo National Park, South Africa

Satellite‐derived vegetation indices were used to identify a geochemical mound of higher active greenness in the Karoo National Park, Beaufort West, South Africa. We determined whether this mound was occupied by plants with higher CO2 assimilation rate. Plant cover on and off the mound was determined. Three woody species with high cover were selected for further investigation. Two deep‐rooted species, Rhigozum obovatum Burch. and Eriocephalus ericoides (L.f.) Druce, showed greater net CO2 assimilation rates on the mound. Net CO2 assimilation rates for the third species, Pentzia incana (Thunb.) Kuntze were similar both on and off the mound. In an attempt to find a mechanistic basis for the elevated CO2 assimilation rates, the relationships between soil factors, foliar nutrients and CO2 assimilation capacity were also examined. Our results suggest that the elevated net CO2 assimilation was not mediated via improved soil or plant water relations on the actively greening mound, nor through a difference in nitrogen levels in the soil or plant material, but possibly by way of the higher sub‐soil phosphorus levels measured from the geochemical mound. Genotype and cover cannot alone be used for rangeland condition assessment since localized elevated soil nutrient status (patchiness) contributes to greater photosynthetic carbon gain which may confer superior browsing responses to plants occurring on these mounds.

Nitrogen Lost during MSW Composting at Two Facilities in Spain

▪ The objective of this study was to evaluate and compare nitrogen losses during the composting process developed at two facilities. Both are in Catalonia, which is located in northeast Spain. The research evaluated the effects of process, feedstock content, differences in compost maturity and other factors to explain differences in nitrogen levels. Separation methods and leachate problems were also compared.

Effects of the mineral composition and water content of intact plants on the fitness of the African armyworm

The effects of organic nitrogen, nitrate, phosphorus, potassium and water content of leaves of intact maize plants, grown in a gravel culture system, on the fitness of the African armyworm, Spodoptera exempta (Walker)(Lepidoptera: Noctuidae) were studied. Organic nitrogen concentrations ranged from 1.3% to 3.7% over four treatments differing only in nitrate supply to the plants. Water content and other mineral levels were all positively correlated with the organic nitrogen level. Feeding damage by the caterpillars was most severe on the lowest nitrate treatments, where it could be least well compensated for by new leaf growth. Larval and pupal fitness variables were not affected by treatment, except for larval development on the lowest nitrate treatment which was delayed by just 1 day. The large compensatory capacity of the larvae was underlined by a similar mineral composition of the pupae in all treatments. Adult fitness variables hardly differed between the upper three nitrate treatments, but revealed a trend over all treatments: the higher the organic nitrogen content of the leaves, the shorter the pre-oviposition period and the higher the fecundity. This trend, however, might have been due to differences in available food quantity rather than in food quality. It is concluded that fitness of the African armyworm is only slightly affected over a wide range of nitrogen concentrations in its food. Though effects might be larger under field conditions, the large differences in outbreak development between years seem not to be attributable to observed differences in nitrogen levels in host plants between years in primary outbreak areas. Other environmental factors appear to be of greater importance.

A Simple and Rapid Test, Using the Ninhydrin Method, For the Determination of The Nitrogen Status of Fruit Trees

Shoots, stem bark and roots from 13 fertilizer trials on apple, peach and orange trees growing in commercial orchards in Victoria (Australia) were sampled during winter and their content of free amino-nitrogen determined by a simple colorimetric ninhydrin method.The values thus obtained from trees growing under different levels of nitrogen showed wider differences than those obtained by conventional leaf analysis for total N. The largest differences in nitrogen levels were present in the roots rather than in the above-ground parts of the trees sampled.The ninhydrin method is simple and rapid and can be carried out during winter on root or bark pieces in advance of the normal time of applying fertilizers.

THE EFFECT OF VARIOUS ORGANIC AMENDMENTS ON CERTAIN CHEMICAL PROPERTIES OF SOIL, ON PLANT NUTRIENT LEVELS IN STRAWBERRY FOLIAGE AND ON FRUIT YIELDS

In a field experiment applications of manure decreased soil acidity but increased total nitrogen, organic matter and adsorbed plus easily acid–soluble phosphorus. Where either peat moss or sawdust was applied there was an increase in soil acidity, total nitrogen and organic matter. The effects of other treatments, e.g., hay and hay compost, were less marked.The phosphorus level in strawberry leaf samples from manured plots reflected the improved phosphorus status of the soil but none of the treatments resulted in significant differences in levels of nitrogen, potassium or calcium in the leaves.All treatments gave highly significant increases in yield. However, the yield with either hay compost or hay was significantly higher than with manure.