Evaluation and control of the nutritional status of cereals

Summary The concept of varying pure-effects of nutrients on final yield, implying that all other growth factors are optimal relative to the concentration of the relevant nutrient, led to determination of reliable absolute and relative reference values for evaluating the nutritional status of young plants based on their chemical composition.The reference values were established from selected experimental data belonging to upper borderlines in the relationships between grain yield and concentrations of various nutrients in aerial parts of oats and spring wheat at fixed dry matter weight levels (DMw-levels).The selected data suggested definite absolutely optimal concentrations and varying relatively optimal concentrations of various nutrients, the latter dependent on the concentration of the pure-effect nutrient.Absolutely and relatively optimal concentrations of various nutrients in young plants at fixed DMw-levels constitute the foundation for developing methods of diagnosis and prognosis.Department of Soil Fertility and Plant Nutrition. Present addressHydrotechnical Laboratory.Hydrotechnical Laboratory.     

Evaluation and control of the nutritional status of cereals

Summary A quantitative therapy method was developed for predicting and controlling grain yields of oats and spring wheat based on methods of diagnosis and yield pronosis and on effects of supplementary applications of nutrients on the chemical composition of the young plant at a fixed Dry Matter weight-level.The characteristic interactions integrated in the models of therapy and depending on kind, source, amount and combination of the nutrient applications on the chemical composition of the young plant allow selection of the best possible nutrient therapy under the given circumstances.The therapy method, tested by comparing predicted with experimentally obtained nutrient concentrations in the young plant, was proved reliable by the high and highly significant correlation coefficients (r>0.9;p<0.001). The correctness of the basic concepts underlying the therapy method, was thus indirectly confirmed and the possibility to use the method in agricultural practice would appear promising.     

Identification of operative dose of NPK on yield enhancement of desi and kabuli chickpea (Cicer arietinum L.) in diverse milieu

The effect of fertilizer on yield and yield related traits studied in two consecutive years at two different locations. Three different doses of fertilizer (NPK) applied at the rate of 9:23:0, 18:46:12 and 27:69:25 respectively on sixteen chickpea, genotypes (Desi and Kabuli advance lines and commercial varieties). Data recorded for days to 50% flowering, plant height, primary and secondary branches, pods per plant, 100-grain weight and grain yield (kg/ha). In Desi chickpea highest grain yield (kg/ha) in both years was produced by advance line D-12026 and in Kabuli advance line K-70005 at Faisalabad location. Grain yield kg/ha had significant positive correlation with all the considered parameters except days to 50% flowering and days to 50% maturity. The treatment comparison manifested that fertilizer doses 9:23:0 enhanced grain yield. The high dose of fertilizer is not recommendable. The grain yield of Desi and Kabuli chickpea at two locations Pulses Research Institute (PRI) Faisalabad and GBRSS (Gram Breeding Research Sub Station) Kallurkot had significant variation. The grain yield (kg ha⁻¹) was significant high in research area of PRI, Faisalabad in both years. The NPK 9:23:0 found operative dose of fertilizer for chickpea.     

Evaluation and control of the nutritional status of cereals

Summary Methods of diagnosis, yield prognosis and therapy, main part of a fertilization system for spring sown cereals, based on results from pot experiments were successfully transferred to results from field experiments in Scandinavia under widely varying conditions. At the selected DMw-level of 0.2 g per plant the optimal chemical composition of the young plant associated with highest obtained yields was: 5.0% N, 0.55% P, 5.2% K, 0.10% Na, 5.3% (K+? Na), 0.15% Mg, 1.0% Ca, 60 ppm Mn and 8 ppm Cu. The optimal chemical composition was independent of species and variety, soil type and region, allowing the methods to be based on solely one set of models. The selected DMw-level-model niveau or standard dry weight-was low compared with that for pot cultures making early diagnosis and therapy possible under field conditions. A correction model was developed in order to estimate the chemical composition of the plant at model niveau from the chemical composition of the plant sampled at any time during early growth and with the view to apply the fertilization system to agricultural practice. Note: As the present paper solely deals with the transfer of a particular fertilization system from pot to field conditions, the references are restricted to the previous papers in this series.     

Rice grain zinc concentrations as affected by genotype, native soil-zinc availability, and zinc fertilization

The development of rice (Oryza sativa L.) cultivars with a higher Zn content in their grains has been suggested as a way to alleviate Zn malnutrition in human populations subsisting on rice in their daily diets. This study was conducted to evaluate the effects of native soil Zn status and fertilizer application on Zn concentrations in grains of five rice genotypes that had previously been identified as either high or low in grain Zn. Genotypes were grown in field trials at four sites ranging in native soil-Zn status from severely deficient to high in plant available Zn. At each site a −Zn plot was compared to a +Zn plot fertilized with 15 kg Zn ha⁻¹. Results showed that native soil Zn status was the dominant factor to determine grain Zn concentrations followed by genotype and fertilizer. Depending on soil-Zn status, grain Zn concentrations could range from 8 mg kg⁻¹ to 47 mg kg⁻¹ in a single genotype. This strong location effect will need to be considered in estimating potential benefits of Zn biofortification. Our data furthermore showed that it was not possible to simply compensate for low soil Zn availability by fertilizer applications. In all soils fertilizer Zn was taken up as seen by a 50–200% increase in total plant Zn content. However, in more Zn deficient soils this additional Zn supply improved straw and grain yield and increased straw Zn concentrations by 43–95% but grain Zn concentrations remained largely unchanged with a maximum increase of 6%. Even in soils with high Zn status fertilizer Zn was predominantly stored in vegetative tissue. Genotypic differences in grain Zn concentrations were significant in all but the severely Zn deficient soil, with genotypic means ranging from 11 to 24 mg kg⁻¹ in a Zn deficient soil and from 34 to 46 mg kg⁻¹ in a high Zn upland soil. Rankings of genotypes remained largely unchanged from Zn deficient to high Zn soils, which suggests that developing high Zn cultivars through conventional breeding is feasible for a range of environments. However, it may be a challenge to develop cultivars that respond to Zn fertilizer with higher grain yield and higher grain Zn concentrations when grown in soils with low native Zn status.     

The effect of deep placement and surface application of nitrogen fertilizers at different light intensities on growth and yield of wetland rice

Summary Lowland rice (RD 3) was cultivated in containers of clay soil submerged with 5 cm water under controlled conditions in the phytotron. Deep placement of urea supergranules 5 cm in the soil significantly enhanced both plant growth and fertilizer efficiency when the plants were cultivated under high light intensity (70 Wm^–2). At the highest urea level grain yield increased 119% above the control level, while growth and fertilizer efficiency was not as high when deep placement of calcium nitrate was used.The application of urea prills and calcium nitrate (18.4g Nm^–2) in two split doses on the soil surface increased grain yield as much as 91% above the control level. At the lower nitrogen concentration (9.2 g N m^–2), the urea prills were more efficient than calcium nitrate as indicated by the grain yield. The height of those plants fertilized by surface application was affected by the concentration and not the type of fertilizer. The number of tillers, however, was significantly higher on urea fertilized plants.When the rice plants were cultivated under low light intensity 930 Wm^–2), neither the nitrogen fertilizers nor the method of application had a significant effect on growth and yield.     

Effects of hybrid and maturity on performance and nutritive characteristics of forage maize at high latitudes, estimated using the gas production technique

We evaluated effects of hybrid and advancing plant maturity on performance, chemical composition, and nutritional characteristics of whole plant forage maize as well as the relative contributions of its plant fractions at high latitudes. Three maize hybrids, Avenir (FAO 180), Isberi (FAO 190) and Burli (FAO 210), were grown in southern Sweden in a field experiment with a replicated complete randomized block design. Plants were harvested four times during maturation, and dry matter (DM) yield and DM as a proportion of fresh weight were recorded. Whole plants were separated into four morphological fractions representing stems, leaves, kernels and cobs and the contribution of each fraction to the DM of the whole plant was estimated. Plant material was subjected to chemical analysis followed by measurement of in vitro gas production (GP) in buffered rumen fluid and finally, by calculation of in vitro true digestibility of organic matter (OM) and neutral detergent fibre (aNDFom). The GP profiles were fitted to a first order kinetic model with a discrete lag. Parameters describing the GP profiles were used in a recently developed mechanistic two compartment rumen degradation model to estimate in vivo OM digestibility (OMD) and first order rate of degradation in the rumen. Hybrids were compared and effects of maturity were assessed by analysis of variance using DM concentration as covariate. There were differences (P<0.05) among the hybrids in DM yield and relative contributions of the plant fractions. Differences (P<0.05) in modelled in vivo digestibility of OM and rates of degradation also occurred among hybrids. Increased maturity caused a reduction in in vitro digestibility of aNDFom in all plant fractions (P<0.05), but increased the rate of rumen degradation of OM in the whole plant as evaluated from GP results. The DM yield had a quadratic relationship with increasing maturity, with maximum yield at a DM concentration of about 370 g/kg. In vitro GP can describe the nutritive characteristics of forage maize in relation to advancing maturity and increased maturity affected agronomic performance and plant composition as well as the nutritive characteristics of hybrids.     

EFFECTS OF COPPER-ENRICHED COMPOSTS APPLIED TO COPPER-DEFICIENT SOIL ON THE YIELD AND COPPER AND ZINC UPTAKE OF WHEAT

A pot experiment and a field experiment were conducted to investigate Cu-enriched composts made from Elsholtzia splendens plants as basal fertilizers to correct Cu deficiency in winter wheat (Triticum aestivum L.) grown in Cu-deficient soils. An application of the compost significantly increased plant height, biomass, grain yield, and 1000-grain weight. In the pot experiment, plant height and shoot biomass in the 2% Cu-rich compost treatment increased 0.8- and 5.2-fold compared with the chemical fertilizer treatment at the mature stage. Compared to chemical fertilizer control, the 2% Cu-enriched compost addition increased grain yield per pot by about 9.5-fold and 1000-grain weight by about 50%. In the field study, the compost also showed stimulatory effects on plant growth and grain yield. The results indicate that composting E. splendens plants grown in a Cu-contaminated soil and then applying the compost to a Cu-deficient soil may be an effective technique for the remediation of contaminated soils and redistribution of the copper as a plant nutrient for copper-deficient soils.     

Use of plant residues for improving soil fertility, pod nutrients, root growth and pod weight of okra (Abelmoschus esculentum L)

The effect of wood ash, sawdust, ground cocoa husk, spent grain and rice bran upon root development, ash content, pod yield and nutrient status and soil fertility for okra (Abelmoschus esculentum L NHAe 47 variety) was studied. The five organic fertilizer treatments were compared to chemical fertilizer (400kg/ha/crop NPK 15-15-15) and unfertilized controls in four field experiments replicated four times in a randomized complete block design. The results showed that the application of 6tha(-1) of plant residues increased (P<0.05) the soil N, P, K, Ca, Mg, pH, and SOM; pod N, P, K, Ca, Mg and ash; root length; and pod yield of okra in all four experiments relative to the control treatment. For instance, spent grain treatment increased the okra pod yield by 99%, 33%, 50%, 49%, 65% and 67% compared to control, NPK, wood ash, cocoa husk, rice bran and sawdust treatments respectively. In the stepwise regression, out of the total R(2) value of 0.83 for the soil nutrients to the pod yield of okra; soil N accounted for 50% of the soil fertility improvement and yield of okra. Spent grain, wood ash and cocoa husk were the most effective in improving okra pod weight, pod nutrients, ash content, root length and soil fertility whereas the rice bran and sawdust were the least effective. This was because the spent grain, wood ash and cocoa husk had lower C/N ratio and higher nutrient composition than rice bran and sawdust, thus, the former enhanced an increase in pod nutrients, composition for better human dietary intake, increased the root length, pod weight of okra and improved soil fertility and plant nutrition crop. The significance of the increases in okra mineral nutrition concentration by plant residues is that consumers will consume more of these minerals in their meals and monetarily spend less for purchasing vitamins and mineral supplement drugs to meet health requirements. In addition, the increase in plant nutrition and soil fertility would help to reduce the high cost of buying synthetic inorganic fertilizers and maintain the long term productivity of soils for sustainable cultivation of okra.     

猪场废水施用对直播稻磷素吸收利用与氮磷生态化学计量的影响

以直播稻为对象,在上海农场进行了猪场处理废水基肥和穗肥不同用量组合的田间试验,研究猪场废水对水稻磷养分吸收利用与氮磷生态化学计量的影响。结果表明:施用猪场处理废水对直播水稻干物质积累、植株磷含量有显著影响。水稻拔节期、齐穗期和成熟期干物质积累量以及产量随废水施用量增加而增加;拔节期、齐穗期和成熟期植株、秸秆及籽粒含磷量与废水用量皆呈显著正相关;不同施肥处理在整个生育期水稻植株N∶P为3.13~5.10,在拔节期、齐穗期、成熟期分别为3.13~4.83、3.42~4.35、3.98~5.10,总体上以齐穗期N∶P值较低;成熟期秸秆N∶P值变动较大(4.30~6.57),而籽粒变化较小(3.85~4.37);齐穗期植株、成熟期秸秆、籽粒和植株的N∶P值与废水施用总量皆呈显著正相关,表明废水施用对直播稻氮素吸收的促进作用大于磷素。     

Sulfur and nitrogen nutrition status in flag leaf and shoot samples collected from wheat growing areas in Çukurova,Central Anatolia and GAP regions of Turkey

Sulfur (S) deficiency in soils and plants has been increased in the recent decade which is reducing crop yield and quality. Unfortunately, no extensive study has been conducted on S nutritional status of plants in Turkey. In this study, soil and plant samples were collected from Çukurova, Central Anatolia and GAP regions where wheat is extensively cultivated. Plant samples either as flag leaf or the whole shoot were collected depending on growth stage of wheat crop at sample collection. Similarly, surface (0–20 cm) and sub-surface (20–40 cm) soil samples were collected from plant sampling sites and a total 963 plant and 1947 soil samples were collected during the study. The S concentration in flag leaf samples varied between 0.18 and 0.67%, 0.11–0.59% and 0.17–0.82% for central Anatolia, Çukurova and GAP regions, respectively. According to S concentration in flag leaf samples, 99% of the plants in Çukurova region were found sufficient in S nutrition. However, 49% of the samples collected from central Anatolia and GAP regions were deficient in S. Critical N:S ratio indicating S nutrition status of plants was lower than the widely accepted critical value of 17. This low N:S ratio was a consequence of deficient N nutrition rather than S nutrition. Moreover, it was observed that plant available SO₄-S concentration of soils varied within and among sampled provinces with an average value of 20.6 and 31.6 mg kg⁻¹ for surface and sub-surface samples, respectively. The SO₄-S concentration increased with increasing soil depth. The results indicate a significantly positive correlation between S concentration in plant shoot and plant available SO₄-S concentration in soils. In conclusion, S-containing fertilizer use in central Anatolia and GAP regions must be considered as an important approach for the prevention of yield and quality losses. Furthermore, rapid and sensitive plant and soil analysis methods are needed, which must also consider the local and site-specific conditions.     

Soil and plant tests for available sulfur in wetland rice soils

Summary Soil tests, plant performance, and plant tissue analyses were used to study the availability of sulfur to wetland rice in 30 Philippine soils. The critical concentrations of available sulfur by the calcium phosphate, lithium chloride, ammonium acetate, and hydrochloric acid extractions were 9, 25, 30, and 5 mg/kg, respectively. The critical total sulfur limits were 0.11% in the shoot at maximum tillering 0.055% in the straw at maturity, and 0.065% in the grain. The critical N:S ratio was 15 in the shoot at maximum tillering, 14 in the straw at maturity, and 26 in the grain. The critical sulfate-sulfur limit was 150 mg/kg in the shoot at maximum tillering and 100 mg/kg in the straw at maturity. The critical sulfate-sulfur/total sulfur percentage ratio was 15% in the shoot at maximum tillering and the straw at maturity. Plant performance, judged by appearance and yield of dry matter, straw, and grain, was generally poorer in the sulfur deficient soils than in the other soils. Although the calcium phosphate and ammonium acetate methods gave a better correlation between plant performance and available sulfur than the others, all four methods separated sulfur-deficient soils from non-deficient ones. The hydrochloric acid method merits further study because it is simple and versatile.     

Nitrogen, phosphorus and potassium nutritional status of semiarid steppe grassland in Inner Mongolia

In grazed semiarid steppe ecosystems, much attention has been paid to aspects of growth limitation by water. So far, potential limitation of primary production by plant nutrients was rarely considered. This knowledge is essential for identification of sustainable land-use practices in these large and important ecosystems on the background of over-exploitation and climate change. In the present study plant nutrient concentrations and ratios were investigated with factorial additions of water and N fertilizer at two sites with contrasting soil nutrient availability. Combined analysis of nutrient concentrations, contents, biomass production, and plant N:P ratios consistently confirmed primary growth limitation by water and a strong N limitation when sufficient amounts of water were supplied. P limitation only occurred at the site with low P availability when in addition to the natural supply, water and N fertilizer were given. According to reported thresholds of N:K and K:P ratios, K was not limiting in any plot. The observed nutritional patterns in the plant community were related to the dynamics of species composition and their specific nutrient status. Stipa grandis had the highest N:P ratio whereas Artemisia frigida showed lowest N:P. These nutrient characteristics were related to growth strategies of dominant species. Accordingly, the relative biomass contribution of S. grandis and A. frigida strongly affected the nutrient status of the plant community. Plant N:P ratios indicate the relative limitation by N or P in the semiarid grasslands under sufficient water supply, but other methods of nutritional diagnosis should be used when plant N:P ratios remain below critical values.     

氮肥运筹对晚播冬小麦氮素和干物质积累与转运的影响

氮素平衡对干物质积累与分配的影响是农业生态系统研究的重要内容,在保障产量前提下减少氮肥施用量可减少环境污染与温室气体排放。以晚播冬小麦为研究对象,设置4个施氮量水平:0 kg/hm2(N0)、168.75 kg/hm2(N1)、225 kg/hm2(N2)、281.25 kg/hm2(N3),每个施氮量水平下设置2个追氮时期处理:拔节期(S1)、拔节期+开花期(S2),研究了氮肥运筹对晚播冬小麦氮素和干物质积累与转运及氮肥利用率的影响。结果表明:拔节期追施氮肥(S1)条件下,在225 kg/hm2(N2)基础上增施25%氮肥(N3)对开花期氮素积累总量和营养器官氮素转运量无显著影响;拔节期+开花期追施氮肥(S2)条件下,随施氮量增加,开花期氮素积累总量和花后营养器官氮素转运量升高;S2较S1显著提高成熟期籽粒及营养器官氮素积累量、花后籽粒氮素积累量及其对籽粒氮素积累的贡献率。同一施氮量条件下,S2较S1提高了成熟期的干物质积累量、开花至成熟阶段干物质积累强度和花后籽粒干物质积累量。同一追氮时期条件下,籽粒产量N2与N3无显著差异,氮肥偏生产力随施氮量增加而降低;同一施氮量条件下,S2较S1提高了晚播冬小麦的籽粒产量和氮肥吸收利用率。拔节期+开花期追施氮肥,总施氮量225kg/hm2为有利于实现晚播冬小麦高产和高效的最优氮肥运筹模式。     

Initial Effects of Differently Treated Biogas Residues from Municipal and Industrial Wastes on Spring Barley Yield Formation

Soil application of biogas residues (BGRs) is important for closing nutrient cycles. This study examined the efficiency and impact on yields and yield formation of solid-liquid separated residues from biodegradable municipal and industrial wastes (bio-waste) in comparison to complete BGRs, nitrification inhibitor, agricultural BGRs, mineral fertilizer and unfertilized plots as control. The experiment was set up as a randomized block design on silt loam Cambisol. Biogas residues from four biogas plants were evaluated. Plants per m², ears per plant, grains per ear and thousand grain weight (TGW) were measured at harvest. Fertilization with BGRs resulted in similar biomass yields compared with mineral fertilizer. Mineral fertilizer (71 dt/ha) and plots fertilized with liquid fraction (59–62 dt/ha) indicated a trend to higher yields than solid fraction or complete BGR due to its high ammonia content. Liquid fractions and fraction with nitrification inhibitor induced fewer plants per m² than corresponding solid and complete variants due to a potential phytotoxicity of high NH₄-N concentration during germination. However, barley on plots fertilized with liquid fraction compensated the disadvantages at the beginning during the vegetation period and induced higher grain yields than solid fraction. This was attributable to a higher number of ears per plant and grains per ear. In conclusion, BGRs from biodegradable municipal and industrial wastes can be used for soil fertilization and replace considerable amounts of mineral fertilizer. Our study showed that direct application of the liquid fraction of BGR is the most suitable strategy to achieve highest grain yields. Nevertheless potential phytotoxicity of the high NH₄-N concentration in the liquid fraction should be considered.     

微生物菌肥对寒地大豆根围土壤细菌群落和产量的影响

通过施用微生物菌肥研究寒地大豆根围土壤细菌多样性和群落组成,缓解因长期施用化肥和农药带来的土壤问题。以大豆合农69为研究对象,设置6个处理：施用大豆专用肥、颗粒肥、复合菌肥、减施15%化肥配施颗粒肥、减施15%化肥配施微生物复合颗粒肥和空白对照,采用高通量测序技术分析大豆荚期根围土壤细菌多样性和群落组成;采用传统统计学方法对株高、荚数、粒数和产量进行统计。门水平放线菌门(Actinobacteria)、变形菌门(Proteobacteria)、酸杆菌门(Acidobacteria)、绿弯菌门(Chloroflexi)、芽单胞菌门(Gemmatimonadetes)、拟杆菌门(Bacteroidetes)、Patescibacteria和WPS-2为优势菌门。其中减施15%化肥配施颗粒肥处理的优势菌门为变形菌门,其他几个处理的优势菌门为放线菌门;目、科和属水平Gaiellales/Other、酸杆菌目(Acidobacteriales/Other)、Frankiales/Other、鞘脂单胞菌属(Sphingomonas)、嗜酸栖热菌属(Acidothermus)、芽单胞菌属(Gemma...     

Barley response to nitrogen and non-nutritional benefits of legume green manure

Green manure application may benefit subsequent crops not only by improving nitrogen (N) fertility but also via non-nutritional mechanisms. The quantification of the latter effect, however, is complicated by the confounding effect of N fertility. Two experiments were conducted in controlled environments to partition the yield response of barley to green manure between N and non-nutritional effects. Each experiment included a factorial of fertilizer N application rates and green manure application rates. The fertilizer was labelled with ¹⁵N to facilitate discrimination between N sources. Approximately 24% of the N applied in green manure was assimilated by barley after 45 days (Experiment 1) and 32% was recovered by barley grown to maturity (Experiment 2). Apparent recovery of green manure-N by barley was not appreciably affected by fertilizer application. Regression analysis of the relationship between dry matter yield and plant N uptake demonstrated that yield responses to green manure application were not entirely attributable to improved N fertility. For a given amount of N assimilated by the crop, yields were higher in green manure-amended treatments than in those receiving no green manure. In barley grown to maturity, barley response to N and non-nutritional effects were estimated to be 5.3 and 2.2g pot⁻¹, respectively. The relationship between dry matter yield and N uptake is suggested as a method for distinguishing nutritional and non-nutritional yield responses. This approach assumes that no other nutrient is limiting growth. The presence of non-nutritional benefits observed in this study demonstrates that the agronomic value of green manure is not limited to N release and casts doubt on the assumptions inherent to calculation of fertilizer equivalents. Contribution 3879132 Contribution 3879132     

Effects of Rhodobacter capsulatus inoculation in combination with graded levels of nitrogen fertilizer on growth and yield of rice in pots and lysimeter experiments

A pot and a lysimeter experiment were carried out to study the effects of inoculation of the roots of rice seedlings with R. capsulatus in combination with graded levels of nitrogen (N) fertilizer on growth and yield of the rice variety Giza 176. Inoculation increased all the measured growth parameters and yield attributes, but the statistically significant differences at all N levels tested were only those for plant dry weight, number of productive tillers, grain and straw yields. The absolute increases in grain yield of the pot experiment due to inoculation were 0.63, 0.93 and 1.22 ton ha^–1 at 0, 47.6 and 95.2 kg N ha^–1, respectively. The results suggest that inoculation along with 47.6 kg N ha^–1 can save 50% of the nitrogen fertilizer needed for optimum G176 rice crop. However, inoculation along with 95.2 kg N ha^–1 can increase grain yield by about 1.2 ton ha^–1. This is probably the first reported evidence of a beneficial effect of phototrophic purple nonsulphur bacteria on rice growth and yield under flooded soil conditions.     

Soil water content and photosynthetic capacity of spring wheat as affected by soil application of nitrogen-enriched biochar in a semiarid environment

A field trial was conducted to determine the effect of nitrogen-enriched biochar on soil water content, plant’s photosynthetic parameters, and grain yield of spring wheat at the Dingxi Experimental Station during the 2014 and 2015 cropping seasons. Results showed that biochar applied with nitrogen fertilizer at a rate of 50 kg ha^–1 of N (BN₅₀) increased soil water content in the 0–30 cm depth range by approximately 40, 32, and 53% on average at anthesis, milking, and maturity, respectively, compared with zero-amendment (CN₀). Stomatal conductance and net photosynthetic rate after the BN₅₀ treatment increased by approximately 40 to 50% compared to CN₀. Soil water content and photosynthetic traits also increased in other treatments using straw plus nitrogen fertilizer, but to lesser extent than that of BN₅₀. Grain yields were highest (1905 and 2133 kg ha^–1 in 2014 and 2015, respectively) under BN₅₀. From this, biochar appears to have a potential for its use with N-fertilizer as a cost-effective amendment for crop production in semiarid environments.     

Zinc,Iron, Manganese and Copper Uptake Requirement in Response to Nitrogen Supply and the Increased Grain Yield of Summer Maize

The relationships between grain yields and whole-plant accumulation of micronutrients such as zinc (Zn), iron (Fe), manganese (Mn) and copper (Cu) in maize (Zea mays L.) were investigated by studying their reciprocal internal efficiencies (RIEs, g of micronutrient requirement in plant dry matter per Mg of grain). Field experiments were conducted from 2008 to 2011 in North China to evaluate RIEs and shoot micronutrient accumulation dynamics during different growth stages under different yield and nitrogen (N) levels. Fe, Mn and Cu RIEs (average 64.4, 18.1and 5.3 g, respectively) were less affected by the yield and N levels. ZnRIE increased by 15% with an increased N supply but decreased from 36.3 to 18.0 g with increasing yield. The effect of cultivars on ZnRIE was similar to that of yield ranges. The substantial decrease in ZnRIE may be attributed to an increased Zn harvest index (from 41% to 60%) and decreased Zn concentrations in straw (a 56% decrease) and grain (decreased from 16.9 to 12.2 mg kg⁻¹) rather than greater shoot Zn accumulation. Shoot Fe, Mn and Cu accumulation at maturity tended to increase but the proportions of pre-silking shoot Fe, Cu and Zn accumulation consistently decreased (from 95% to 59%, 90% to 71% and 91% to 66%, respectively). The decrease indicated the high reproductive-stage demands for Fe, Zn and Cu with the increasing yields. Optimized N supply achieved the highest yield and tended to increase grain concentrations of micronutrients compared to no or lower N supply. Excessive N supply did not result in any increases in yield or micronutrient nutrition for shoot or grain. These results indicate that optimized N management may be an economical method of improving micronutrient concentrations in maize grain with higher grain yield.