Nitrogen In Proportion Research Articles

Nontarget effects of pre‐emergent herbicides and a bioherbicide on soil resources, processes, and communities

Community‐type conversions, such as replacement of perennials by exotic annual grasses in semiarid desert communities, are occurring due to plant invasions that often create positive plant–soil feedbacks, which favor invaders and make restoration of native perennials difficult. Exotic annual grass control measures, such as pre‐emergent herbicides, can also alter soil ecosystems directly or indirectly (i.e. via the plant community), yet there are few studies on the topic in natural, non‐cropped landscapes. We asked how spray treatments applied to soil post‐fire with the intention of inhibiting invasive annual grasses (such as Bromus tectorum L.) and releasing existing native perennial grasses affected soil resources, a microbial process, and invertebrates in three climatically varied sagebrush steppe sites. Spray treatments included chemical herbicides (imazapic and rimsulfuron) that strongly affected plant communities and a bioherbicide (Pseudomonas fluorescens strain D7) that did not. Chemical herbicides increased soil mineral nitrogen in proportion to their negative effects on plant cover for 2 years after treatments in all sites and increased soil water and net N mineralization (measured at one site) but did not affect total carbon, nitrogen, or organic matter. Invertebrate responses to herbicides varied by site, and invertebrates increased with chemical herbicides at the highest, wettest site. We show that herbicide treatments can exacerbate pulses of mineral nutrients, which previous studies have shown can weaken ecosystem resistance to invasion. Thus, restoration strategies that increase the likelihood that desired plants can capture mineralized nutrients after herbicide application will likely be more successful.

Effect of fertilizers enriched with bio-based carriers on selected growth parameters, grain yield and grain quality of maize (Zea mays L.)

Low efficiency of nutrient use, especially nitrogen, from mineral fertilizers under the drought conditions is a worldwide problem in agriculture. Therefore, low-cost, and environmentally friendly technologies that improve the utilization of nutrients from applied fertilizers while increasing water availability to plants are urgently needed. The aim of our research was to prepare bio-based carriers composed from different ratios of natural hydroabsorbent (NHA), synthetic superabsorbent polymer (SAP), and zeolite. The commercial fertilizers (NP and NPK) were enriched with these carriers with subsequent determination of their ability to release nutrients and affect the growth of maize plants grown under drought conditions. The first (i) part of our experiment focused on the lab preparation of bio-based carriers followed by a testing of their abilities to release nitrogen into water in the lab conditions. The effect of selected carriers in the mixture with commercial fertilizers to the growth of maize were subsequently tested under the optimal and limited watering regime in the greenhouse pot experiment (ii). The control treatment (no fertilizer) and fertilization treatments were established, namely, single bio-based carrier (C2) and compound fertilizers (NP, NPK) and their mixture (C2-NP, C2-NPK). The effect of these fertilizers applied in two doses (at the level of 30 and 60 kg/ha N) on the yield and grain quality of maize (iii) was finally evaluated in a two-year field experiment (2020 – 2021). Based on the existing kinetic models, it was possible to the link nitrogen release to the structural variables of the composite carriers. A small volume of zeolite microparticles incorporated into the biopolymer network of the NHA and SAP carrier accelerated the nitrogen release in the lab experiment (i) and increased the maximum amount of released nitrogen in proportion to the zeolite content without significantly affecting the water-holding capacity. The results of the greenhouse pot experiment (ii) demonstrated that application of a bio-based carrier composed of 7 wt% SAP, 7 wt% zeolite and 86 wt% NHA in combination with NP and NPK fertilizers significantly increased chlorophyll content, the ability of maize plants to absorb radiation in photosystem II, and the weight of above-ground maize biomass under limited and optimal irrigation conditions. The C2-NPK increased grain weight, grain yield and protein content in the grain of maize under the field conditions (iii). Fertilizers enriched with bio-based carrier are a promising alternative to improve soil moisture and increase nutrient availability to plants grown not only in drought conditions.

Numerical simulation of air ionization processes in plasma-actuator electric field

Mathematical model based on drift-diffusion approximation of hydrodynamic method of plasma description with two-temperature approximation was carried out for air ionization case in order to model process of interaction between dielectric barrier discharge plasma actuator and gas flow. Electron-induced ionization-recombination mechanism was used. Air was considered as mixture of molecular oxygen and nitrogen in proportion at normal conditions. Process kinetics was described by electron-induced reactions with molecular nitrogen and oxygen, ions and electron components. Equations system consisted of transport equations for concentrations of all mixture components, electron temperature and equation for electric potential was solved. Extended Scharfetter-Gummel scheme for large quantity of transport equations was developed. It was shown, that main influence on charge distribution has electron temperature. This model could be used for volume and surface charge density estimations necessary for volume force calculation in the vicinity of electrodes.

Impact of deforestation on soil fertility, soil carbon and nitrogen stocks: the case of the Gacheb catchment in the White Nile Basin, Ethiopia.

Abstract The evergreen forests of southwest Ethiopia are important for soil fertility sustenance and climate change mitigation. However, the increasing human population and expansion of agricultural land have led to deforestation. We determine the effect of deforestation on soil fertility, soil carbon and nitrogen stocks and hypothesize that tropical forests and agroforestry have similar characteristics, in contrast to the deforested areas used as cropland. Hence, soil samples (n = 360) have been taken from the natural forest, agroforestry and croplands at four depths (0–20 cm, 20–40 cm, 40–60 cm and 60–80 cm) in three altitudinal belts. The topsoil and subsoil physico-chemical characteristics, pH, organic carbon, total nitrogen, available phosphorus, exchangeable calcium, magnesium, cation exchange capacity and exchangeable base cations were significantly higher in both the forest and agroforestry than in croplands, at all elevation zones. Soil organic carbon and nitrogen stocks in soil under forest are similar to those under agroforestry at all elevation zones (0–20 cm, 20–40 cm, 40–60 cm and 60–80 cm soil depths). However, soil organic carbon and nitrogen stocks in soil under both forest and agroforestry were significantly different from cropland in all elevation zones at all depths except 60–80 cm. The highest total soil organic carbon stocks were recorded in the forest (412 Mg ha−1 at the FH site and 320 Mg ha−1 at the FL site) and agroforestry (357 Mg ha−1 at the DM site, 397 Mg ha−1 at the ZH site and 363 Mg ha−1 at the ZM site). The total organic carbon loss due to the conversion of forest to cropland ranges from 3.3 Mg ha−1 y−1 at the FL site to 8.0 Mg ha−1 y−1 at the FH site. The soil organic carbon and nitrogen losses due to the conversion of forest to cropland are similar to the losses when converting agroforestry to cropland. The total carbon dioxide emission due to the conversion of forest to cropland ranges from 12 Mg ha−1 y−1 at the FL site to 28 Mg ha−1 y−1 at the FH site. Agroforestry has the potential to maintain soil fertility, and stores higher soil organic carbon and nitrogen in proportion to the natural forest. Therefore, it can be suggested that agroforestry has a similar capacity as Afromontane forests to sustain soil fertility as well as to regulate greenhouse gas emissions.

Effects of mountain tea plantations on nutrient cycling at upstream watersheds

Abstract. The expansion of agriculture to rugged mountains can exacerbate negative impacts of agricultural activities on ecosystem function. In this study, we monitored streamwater and rainfall chemistry of mountain watersheds at the Feitsui Reservoir Watershed in northern Taiwan to examine the effects of agriculture on watershed nutrient cycling. We found that the greater the proportion of tea plantation cover, the higher the concentrations of fertilizer-associated ions (NO3−, K+) in streamwater of the four mountain watersheds examined; on the other hand, the concentrations of the ions that are rich in soils (SO42−, Ca2+, Mg2+) did not increase with the proportion of tea plantation cover, suggesting that agriculture enriched fertilizer-associated nutrients in streamwater. Of the two watersheds for which rainfall chemistry was available, the one with higher proportion of tea plantation cover had higher concentrations of ions in rainfall and retained less nitrogen in proportion to input compared to the more pristine watershed, suggesting that agriculture can influence atmospheric deposition of nutrients and a system's ability to retain nutrients. As expected, we found that a forested watershed downstream of agricultural activities can dilute the concentrations of NO3− in streamwater by more than 70 %, indicating that such a landscape configuration helps mitigate nutrient enrichment in aquatic systems even for watersheds with steep topography. We estimated that tea plantation at our study site contributed approximately 450 kg ha−1 yr−1 of NO3-N via streamwater, an order of magnitude greater than previously reported for agricultural lands around the globe, which can only be matched by areas under intense fertilizer use. Furthermore, we constructed watershed N fluxes to show that excessive leaching of N, and additional loss to the atmosphere via volatilization and denitrification can occur under intense fertilizer use. In summary, this study demonstrated the pervasive impacts of agricultural activities, especially excessive fertilization, on ecosystem nutrient cycling at mountain watersheds.

Biochar helps enhance maize productivity and reduce greenhouse gas emissions under balanced fertilization in a rainfed low fertility inceptisol

Maize production plays an important role in global food security, especially in arid and poor-soil regions. Its production is also increasing in China in terms of both planting area and yield. However, maize productivity in rainfed croplands is constrained by low soil fertility and moisture insufficiency. To increase the maize yield, local farmers use NPK fertilizer. However, the fertilization regime (CF) they practice is unbalanced with too much nitrogen in proportion to both phosphorus and potassium, which has led to low fertilizer use efficiency and excessive greenhouse gases emissions. A two-year field experiment was conducted to assess whether a high yielding but low greenhouse gases emission system could be developed by the combination of balanced fertilization (BF) and biochar amendment in a rainfed farmland located in the Northern region of China. Biochar was applied at rates of 0, 20, and 40t/ha. Results show that BF and biochar increased maize yield and partial nutrient productivity and decreased nitrous oxide (N2O) emission. Under BF the maize yield was 23.7% greater than under CF. N2O emissions under BF were less than half that under CF due to a reduced N fertilizer application rate. Biochar amendment decreased N2O by more than 31% under CF, while it had no effect on N2O emissions under BF. Thus BF was effective at maintaining a high maize yield and reducing greenhouse gases emissions. If combined with biochar amendment, BF would be a good way of sustaining low carbon agriculture in rainfed areas.

A 1 MV triggered gas-filled gap

A gas trigatron type gap for a 36-channel ring switch of a five-cascade water-insulated double step forming line with output impedance of 2.9 Ohm “Gamma-1” high-current electron accelerator is described in this paper. At discharge operating voltage of 1 MV its overall dimensions are: height ~ 160 mm, diameter ~ 240 mm. When operated with a mixture of insulating gas and nitrogen in proportion 40%SF6+60%N2 at 17 MPa pressure, the trigger delay is (16 ± 2) ns, with a self-break safety margin of not less than 1.5. The gap electrode surfaces are made of tungsten alloy. When operating as a part of the double step forming line switch, the average energy, switched through a single gap, is 3.3 kJ, and the current is 95 kA.

Influence of different fibre sources on digestibility and nitrogen and energy balances in growing pigs

The present study was undertaken to investigate how three different fibre sources, sugar beet pulp, soya bean hulls and pectin residue, constituting 15% of diets for growing pigs, influenced daily body gain, feed conversion, apparent faecal digestibility and nitrogen and energy balances. Eight castrated crossbreed pigs (30 – 80 kg live weight) were used in a replicated 4 × 4 Latin-square design with one control diet and three fibre containing diets. Daily body weight gain and feed conversion were not affected by the dietary treatments. The apparent faecal digestibility of organic matter (OM) and energy were significantly lower for the fibre diets (OM: 0.81 – 0.85; energy: 0.78 – 0.83) compared to the control diet (OM: 0.88; energy: 0.86). The apparent faecal digestibility of crude protein (CP) was lower for the fibre diets (0.71 – 0.78) compared to the control diet (0.83), although it was only significantly lower for the sugar beet pulp and pectin residue diets. The pectin residue diet, which contained the highest amount of dietary fibre, lignin and insoluble non-starch polysaccharides, had the lowest digestibility of OM, CP and energy. There was a tendency (p = 0.07) for a diet effect on retained nitrogen in proportion to digested nitrogen, where the sugar beet pulp and pectin residue diets had numerically the highest values. Heat production and retained energy in proportion to metabolizable energy intake were not affected by fibre inclusion. It was concluded that the inclusion of sugar beet pulp, soya bean hulls and pectin residue in diets for growing pigs decreased the apparent faecal digestibility and in the diets with sugar beet pulp and pectin residue higher utilization of digested nitrogen for retention compensated for the lower amount of digested nitrogen.

Increased protein degradation and decreased protein synthesis in skeletal muscle during cancer cachexia.

The effects of progressive cachexia on protein metabolism in skeletal muscle has been investigated in mice bearing the MAC16 adenocarcinoma which produces cachexia with tumour burdens of < 1% of the host weight. Weight loss was accompanied by loss of whole body nitrogen in proportion to the overall loss of body mass. Using L-[4-3H]phenylalanine to label proteins in gastrocnemius muscle, a significant depression (60%) in protein synthesis occurred in animals with a weight loss between 15 and 30% accompanied by an increase in protein degradation, which increased with increasing weight loss between 15 and 30%. Muscle degradation in vitro could be achieved by serum from cachectic animals, which appeared to contain a proteolysis-inducing factor. These results suggest that the increased degradation of skeletal muscle seen in this model of cachexia may be due to a circulating proteolysis-inducing factor.

Response of adult rats to deficiencies of different essential amino acids

1. Adult rats were fed on diets free of either lysine, methionine, threonine or protein. The threonine- and protein-deficient animals lost weight at approximately the same rate, about 100 g in 14 weeks, at which time several were moribund. In contrast, lysine-deficient animals lost only about 30 g in 14 weeks and had lost only 46 g after 22 weeks, when they were killed. Methionine-deficient animals showed an intermediate response. Losses in weight of several tissues – kidney, heart and two muscles – were related to, but not necessarily proportional to, the loss of body-weight. Liver weights relative to body-weights were large in lysine- and threonine-deficient animals and smallest in methionine-deficient animals.2. Adult rats were fed on diets containing zero, a moderate amount (about twice the estimated minimal requirement) or an excess (about four times the estimated requirement) of lysine or threonine in all combinations (3 × 3 design). Analysis of variance of the body-weights, tissue weights and tissue nitrogen contents indicated, in general, a significant effect of each amino acid, as expected, but also, in most instances, a significant interaction. Plasma concentrations of lysine and threonine were affected by the intakes of the respective amino acids, but plasma lysine concentrations were also affected by the threonine intake.3. Liver histology also suggested significant interactions between the two amino acids. Animals given no lysine but moderate amounts of threonine developed severely fatty livers; next most severely affected were animals receiving excess of both amino acids. Threonine deficiency, in the presence or absence of lysine, produced moderately fatty livers similar to those seen in protein-deficient animals.4. Since animals have varying ability to conserve body nitrogen when they are fed on diets limiting in different essential amino acids, measurements of biological value (BV) and net protein utilization by conventional methods, over a short period of time, over-estimate nutritive value relative to amino acid score and probably over-estimate the true nutritive value of poor-quality proteins, particularly those limiting in lysine. If so, this is a serious error, since it leads to underestimates of the protein requirements if BV is used. The fact that certain tissues, particularly the liver, do not necessarily lose nitrogen in proportion to total body nitrogen and may show specific pathological effects depending on the limiting amino acid or the proportions of amino acids in the diet also indicates that general measures of nitrogen economy may not be sufficiently discriminating tests of the nutritive value of proteins.

The Nitrogen Nutrition of the Peach Tree II. Storage And Mobilization of Nitrogen in Young Trees

The chemical composition and distribution of storage nitrogen in young peach trees and the importance of this stored nitrogen for new growth were investigated. Young peach trees, which were grown in sand culture for two growing seasons, accumulated nitrogen in proportion to supply during the first year, and the results suggested that this stored nitrogen was utilized for new growth during the second growing season irrespective of the external nitrogen supply. Tree growth in early spring was significantly correlated with the level of storage nitrogen in tree tissues, but after November tree growth was markedly dependent upon the external nitrogen supply. If fertilizer nitrogen was not applied, the supply of storage nitrogen in tree tissues was exhausted by the end of November. Reaccumulation of storage nitrogen began in tree tissues in December and was rapid if the external nitrogen supply was high.

GROWTH AND NITROGEN METABOLISM OF SQUASH SEEDLINGS III. WITH RESPECT TO HIGH AND LOW CARBOHYDRATE SYNTHESIS

Fischer (6), Bornemann (3), Reinau (I5), Lundegardh (8), Arthur (i), and others have studied the effects of added carbon dioxid upon vegetative growth and sexual reproduction. These investigators report increased size and dry weights of many types of plants as a result of enrichment of the atmosphere with carbon dioxid. More recently, Bolas and Henderson (2) have found that addition of carbon dioxid to the air results in a large increase in the dry weight of cucumber plants as compared to results obtained with plants grown in normal air. The increase is evident within two to three days after adding the carbon dioxid. Reese (io) obtained beneficial effects by increasing the carbon dioxid content of the atmosphere in which seedlings and cuttings were growing. Leaves of Aconitum Wilsoni seedlings were three times larger than those of untreated plants. Chrysanthemum and dahlia cuttings rooted more quickly when grown in a carbon dioxid-enriched atmosphere. In previous papers (ii, 12) it has been shown that the ability of seedlings to utilize carbon dioxid depends on the amount of available nitrogen in relation to that of carbohydrates. Seedlings grown from seeds having large reserves of nitrogen in proportion to the non-nitrogenous materials benefited greatly from the utilization of carbon dioxid both when extra nitrogen was supplied and when it was not. The green weights (dry weights not determined) and sizes of all organs increased and that of the roots especially. Seedlings grown from seeds having small reserves of nitrogen in proportion to the carbohydrates (wheat and low-protein corn) were not benefited by supplying carbon dioxid unless extra nitrogen was also given. The dry weights of the organs increased slightly but the sizes did not. In fact the leaves were somewhat stunted. With an abundance of nitrogen available in the substrate, the supplying of carbon dioxid was beneficial, especially in the later stages of seedling growth when the reserves of the seed were becoming depleted. A healthy condition and relatively large size of leaves could be produced on the one hand when the nitrogen supply was limited

SIGNIFICANCE OF THE CHEMICAL COMPOSITION OF THE SECRETING AND DRY MAMMARY GLAND TO MILK SECRETION

The results herein presented furnish exact critical evidence for one more stage in milk secretion. Cows producing up to 30 pounds of milk at one milking are shown to have the lactose equivalent of all this milk in the udder when milking commences. The average excess of lactose found in the udder after subtracting the amount necessary for the contained milk is equal to 2.1 pounds. This represents the milk retained in the udder when the cow is believed to be dry. These conclusions are further supported by the fact that no sugar is found in the udder in the quiescent state. The study of the total composition of the udder as fat, ash, nitrogen, and lactose, and of the contained milk shows that there is a large excess of fat, ash, and nitrogen in proportion to that necessary for milk formation. The excess of udder lactose over the milk lactose is much less. The lactose would therefore appear to be formed from some element in the blood, probably dextrose, only as needed for the formation of milk. The composition of the dry udder is quite different in certain respects from that of the actively secreting gland. It builds up a fat reserve of a quite different Reichert-Meissl number from that of butter-fat. It has no sugar, its ash content is reduced, and the nitrogen content is like that of the secreting gland.

Growth of Seedling in Relation to Composition of Seed

1. Different kinds of seedlings produce very different growth responses when exposed to the same external influences. The responses are often related to the chemical composition of the seed. 2. If the nitrogen content of the seed is low in proportion to the carbohydrates, the response as measured by an increase in total growth in terms of green weight is greater when nitrates but no CO2 (except traces given off in respiration) are utilized than when CO2 but no nitrates are utilized. 3. If the nitrogen content of the seed is high in proportion to the carbohydrates, the response as measured by an increase in total growth is greater when CO2 but no nitrates are utilized than when nitrates but no CO2 (except for traces given off in respiration) are utilized. 4. The greatest total amount of growth, however, is produced by seedlings from both high and low-nitrogen seeds by allowing the seedlings to utilize both nitrates and CO2. 5. The utilization of both nitrates and CO2 tends to result in a shifting of the relative amounts of shoots and roots, that is, there are qualitative as well as quantitative responses to these external influences. The proportion of shoots to roots of low-protein seeds tends to be increased because of the relatively larger increase in the amount of shoots, if nitrates but no CO2 is utilized; whereas the proportions of shoots to roots of seedlings of high-protein seeds are not increased and in some cases are even decreased by this treatment. 6. The shoot to root ratios of seedlings of low-protein seeds are not noticeably affected if CO2 but no nitrates are utilized, but the shoot to root ratios of high-protein seeds tend to be greatly reduced if CO2 but no nitrates are utilized. This shifting of ratios is a result of a greater increase in the amount of roots than of shoots. 7. The proportions of shoots to roots of seedlings of low-protein seeds tend to be slightly increased if both CO2 and NO3 are utilized, but the proportions of shoots to roots of seedlings of high-protein seeds are very greatly decreased by such treatment, because the weight and number of roots increase much more than the shoots. 8. The modification of type of growth is correlated with extent of modification in quantity of growth. Those treatments which result in the greatest increase in quantity of growth are the ones which produce the greatest change in type of growth. (The foregoing statements apply to growth of seedlings in the light.) 9. A high-protein, high-oil food supply appears to be the most efficient in producing growth both in darkness and in light. This is not surprising, since both types of foods are constituted of a relatively large proportion of the condensed compounds of their respective types. For example, high-protein seeds contain relatively much more of basic nitrogen and consequently have a great amount of nitrogen in proportion to their weight; oils contain a great amount of carbon in proportion to their weight. 10. The shoot to root ratios of seedlings grown in darkness appear to vary with the proportion of nitrogen to carbohydrates in the food reserves of the seed, the higher the nitrogen in proportion to carbohydrate content the higher the shoot to root ratios of the seedlings. There is some evidence that addition of nitrates to the culture medium of the seedlings grown in darkness can modify the type of growth (increase shoot to root ratios), but in only a few cases do nitrates increase the amount of growth. 11. Since wide variations in growth responses are associated with variations in the types and quantities of storage materials in the seed, it seems inadvisable to draw conclusions as to the effect of mineral nutrients or carbon dioxide treatment upon the subsequent growth of the plants when the observations are based on growth responses during the first three weeks of growth only. Before studying the effect of an element or compound on growth (in general), it would seem desirable to conduct experiments in which the storage supply of the element or compound in question has been at least partially exhausted, by allowing the seedlings to grow to maximum size without that substance. This method has been employed by animal workers for some time. 12. Although contradictory results have not been found in the different series of experiments, the results are not considered conclusive but will be repeated and elaborated.