Effects of N application strategies on N leaching loss in paddy soil and N use characteristics in different super hybrid rice cultivars

Paddy and Water Environment - A rational nitrogen (N) application strategy effectively improves grain yield and N use efficiency (NUE) in the production of super rice (Oryza sativa L.). This study...     

Effect of root depth penetration on soil nitrogen competitive interactions and dry matter production in pea–barley intercrops given different soil nitrogen supplies

Competition for soil resources plays a key role in the outcome of intercropping systems. In cereal–legume intercrops, competition for soil nitrogen during the vegetative phase greatly influences the final performance of the intercropped species. However, there is a lack of knowledge on the main factors involved in interspecific soil N competitive interactions between species. The dominance of cereals over legumes is often attributed to their faster growing rooting system. Nevertheless, using only field experimental approaches makes it difficult to isolate the effect of one factor because of the strong interactions between processes and the environment. Given the complexity of intercropping systems, dynamic simulation models can be especially helpful for testing hypotheses about the key factors driving competition between species. The present work was designed to investigate, under non-limiting water conditions, through an experimental and modelling approach, whether differences in root depth penetration among pea and barley grown together determined competition for soil N and dry matter accumulation (DM) by each species during the vegetative phase. This hypothesis was tested through several simulated scenarios generated using the STICS crop model. The model was first used to compare competition for soil N according to differences in root depth penetration rates between species. This rooting depth penetration effect was then studied at three levels of soil N supply leading to different degrees of N demand and N stress. A field experiment carried out in 2003 including pea–barley intercrops grown either with 130 kg N ha⁻¹ or without any fertilizer was used to test the model. Experimental results of aboveground biomass, nitrogen accumulation, N₂ fixation and rooting depth monitored regularly during the crop cycle were compared to simulated results. The simulated responses of the intercrops were in agreement with the observations from the experimental dataset. Using the model, it is clear that faster root growth in barley gives it access to more soil nitrogen than pea during the vegetative phase. However, this advantage, which is limited to the vegetative phase, only affects the outcome of the intercrop when soil N supply is low. With higher soil N supplies, soil N sharing is not affected by the differences in rooting depth penetration between species. It appears that with higher N supplies, the differences in N demand between species have more influence on species dominance than differences in rooting depth.     

甘蔗间作花生对不同耕层土壤微生态的影响

甘蔗间作花生是我国华南地区特有的高效种植模式。本文研究了甘蔗/花生间作不同耕层土壤养分、酶、微生物的变化特征及其相关性。结果表明,相比单作而言,0～20 cm间作花生土壤有效氮、有机质、微生物量氮含量、真菌、放线菌数量、蛋白酶活性及间作甘蔗土壤细菌、放线菌、总微生物数量、微生物量氮含量及蛋白酶活性均显著增加;20～40 cm间作甘蔗土壤全磷、全钾、蛋白酶活性及间作花生土壤放线菌、蛋白酶活性显著增加;40~ 60 cm间作花生土壤真菌、蔗糖酶、微生物量碳含量显著增加;相反,间作甘蔗土壤蔗糖酶活性均显著低于单作甘蔗处理;间作土壤有效氮磷钾、有机质含量、脲酶、酸性磷酸酶活性、微生物数量均随着土壤深度的增加而表现出降低的趋势;间作土壤有效养分与脲酶、酸性磷酸酶、微生物量氮及微生物数量呈显著或极显著正相关。表明甘蔗花生间作条件下土壤养分、酶、微生物相互作用,共同维持良好的土壤微生态环境。     

Effects of cutting or grazing grass swards on herbage yield, nitrogen uptake and residual soil nitrate at different levels of N fertilization

On a Flemish sandy loam soil, cut and grazed swards were compared at different levels of mineral nitrogen (N) fertilization. Economically optimal N fertilization rates were 400 (or more) and 200 kg N ha^?1 yr^?1 on cut and grazed swards respectively. Considering the amounts of residual soil nitrate‐N in autumn, these N rates also met the current Flemish legal provisions, i.e. no more than 90 kg ha^?1 nitrate‐N present in the 0–90 cm soil layer, measured between 1 October and 15 November. The N use efficiency was considerably higher in cut grassland systems than in grazed systems, even when the animal component of a cut and conservation system was included. The results indicate that, for cut grasslands, two N application rates should be considered: intensively managed grasslands with high amounts of N (400 kg ha^?1 yr^?1 or more) or extensively managed grasslands with white clover and no more than 100 kg N ha^?1 yr^?1.     

Wide variation in nitrification activity in soil associated with different forage plant cultivars and genotypes

There is a growing interest in using plants to manipulate the nitrification rate in soils with the object of reducing losses of nitrogen from the soil–plant system – lower rates of nitrification being associated with reduced leaching of nitrate and reduced emissions of nitrous oxide. Here we screened the potential nitrification rate in soil associated with 126 cultivars from 26 species representing three functional groups used in temperate managed grassland. Plants were grown in pots, and the nitrification was measured using two approaches: (i) a measure of potential nitrification carried out in the laboratory on soil samples and (ii) a measure of nitrification in the presence of the growing plants using the ratio of nitrate to ammonium () measured on in situ ion exchange membranes after the application of urine. There was about a twofold difference among cultivars in nitrification measured using the potential assay and a 10‐fold difference using the ratio approach. The ranking of nitrification was different using the two approaches perhaps suggesting that the presence of plants in the ratio approach had an effect on the outcome although further work will be necessary to confirm this. Irrespective of the method used, the results demonstrate substantial differences between cultivars but also within cultivars offering the possibility of selection to enhance plant effects on nitrification.     

不同施氮条件下麦田杂草氮素吸收的研究

为了解麦田杂草氮素吸收对施氮量的反应,在半湿润地区,以土垫旱耕人为土为供试土壤,通过田间小区试验,研究了不同施氮水平下冬小麦田间杂草含氮量及吸氮量的变化以及杂草与小麦氮素的竞争关系.结果表明,小麦不同生育时期麦田杂草含氮量存在差异,表现为越冬期＞返青期＞拔节期＞成熟期;杂草含氮量随施氮量的增加而增加,尤其是在小麦生育前期施氮处理间差异达到显著水平.小麦不同生育期的杂草吸氮量呈现先上升后下降的趋势,在拔节期达到最大,各生育期间差异极显著;在小麦不同生育期,杂草吸氮量对施氮水平的反应不同,与不施肥的对照相比,施肥有利于前期杂草对氮素的吸收,中后期表现为降低的趋势.从相对吸氮量看,增加施氮提高了前期杂草对氮素的竞争能力,而后期杂草的竞争力下降.     

Modelling dry matter production and resource use in intercrops of pea and barley

The FASSET whole farm model was extended with a sub-model for competition between several plant species for light, water and nitrogen. The new model was tested on intercrops of pea (Pisum sativum L.) and spring barley (Hordeum vulgare L.). A 3-year dataset on pea and barley sole crop growth was used for calibration. Two datasets that included detailed measurements of crop production, nitrogen uptake and leaf area indices from two sites were used for testing. An arable organic experiment from three sites including several treatments over 4 years was also used for testing.The model predicted the increase in resource utilisation of pea and barley and effects on pea symbiotic nitrogen fixation satisfactorily. The effects of pea interspecific competition on barley production agreed with observations, but the simulated effect of barley interspecific competition on pea was underestimated. Sensitivity analyses showed that the vertical distribution of barley leaf area had a great influence on the outcome of the interspecific competition between the barley and pea crops.     

Effect of applications of organic solid cattle manure on Hungarian vetch and barley intercropping mixtures grown on soils of different depths

Sloping fields on soils of shallow depth to tillage are commonly left uncultivated in many parts of the world. This study was conducted to compare the effects on morphological traits, dry‐matter (DM) yield, legume ratio (LR), crude protein content (CP), crude protein yield (CP yield) and mineral concentrations (N, P, K, S, Ca, Cu, Fe, Mg, Mn, Na, B and Zn) of Hungarian vetch (Vicia pannonica Crantz.) and barley (Hordeum vulgare L.) grown in intercropping mixtures in response to three rates of organic solid cattle manure application (M₀: 0, M₁: 10, M₂: 20 t ha^?1). Experimentation was conducted on soils of two different soil depths [shallow (8–12 cm; low‐medium erosion risk) and normal soil depth (18–22 cm; no erosion risk)] on a sloping field in the 2006–2007 and 2007–2008 growing seasons at Gumushane, Turkey. Herbage harvested on the shallow depth area had 22–73% less DM yield, 14–72% less CP yield, 6–9% greater CP content and generally higher minerals contents than herbage from the normal soil depth area. Cattle manure applications increased DM yield by about 23%, increased CP content and CP yield, and also increased the contents of most minerals in herbage of the intercropping mixtures, relative to the control, averaged over the two soil depths. It is suggested that, for areas with shallow soil depths that are prone to erosion, plant cover should be used for forage production, and that fertilization with solid cattle manure at 20 t ha^?1 can support production of quality forage of acceptable DM yield.     

Evaluation of protein nutritive value in barley and wheat cultivars usingAspergillus flavus

The fungusAspergillus flavus was used to evaluate the protein nutritive value of barley and wheat cultivars with a wide range in protein and amino acid concentrations. The biomass yield, after 72h incubation on isonitrogenous diets, also varied widely among barley or wheat cultivars. However, biomass was more closely associated with sample weight or glucose supplementation of the medium than with amino acid concentrations. Only threonine, serine and histidine in barley proteins gave low positive correlations with biomass yield at all energy levels in the diets, and no consistent correlations were found in the wheat experiment. Also biomass mycelium varied in nitrogen concentration, depending on diet, and biomass weight was not a consistent measure of nitrogen retention by the mycelum. It was concluded thatA. flavus was not a satisfactory organism for rapid screening of barley or wheat cultivars for concentration of available amino acids, essential for human nutrition.     

Morphology and nutritive value of perennial ryegrass cultivars at different phenological stages

Eight perennial ryegrass cultivars (representing the variations in ploidy, heading date and water‐soluble carbohydrates concentration) were investigated for morphology and nutritive value at three phenological stages: pre‐heading vegetative, reproductive and post‐flowering vegetative stages. Chemical compositions and digestibility of morphological components (lamina, pseudostem and reproductive stem) from each perennial ryegrass cultivar were analysed in a split‐plot design. At the vegetative stages, perennial ryegrass cultivars differed significantly in the proportions of lamina and pseudostem. Tetraploid cultivars, Base and Bealey, always had the greatest lamina proportion (51.8% and 53.2% at the pre‐heading and post‐flowering vegetative stages respectively). At the reproductive stage, the emergence of seed heads diminished the differences in morphology among cultivars. Perennial ryegrass cultivars also had distinct nutritive value throughout three phenological stages. The high‐sugar cultivar, AberMagic, had high WSC concentrations (276, 227 and 90 g/kg DM at the pre‐heading vegetative, reproductive and post‐flowering vegetative stages respectively); the intermediate‐heading cultivars, Kamo and Commando, generally had a lower organic matter digestibility in dry matter than the late‐heading cultivars at the pre‐heading vegetative (70.7% vs. 74.4%) and reproductive stage (63.9% vs. 68.2%). However, although the morphological components were different in nutritive value consistently, the differences in morphology did not account for the variation in nutritive value among perennial ryegrass cultivars.     

Xylan-degrading enzymes and arabinoxylan solubilisation in barley cultivars of differing malting quality

The levels of xylanolytic activities ((1→4)-β-endoxylanases, β-d-xylosidases and α-l-arabinofuranosidases) and the levels of water extractable arabinoxylans (WEAX) in hot water extracts of malts were compared during malting of four barley cultivars of differing quality. Endoxylanase activity increased from day 1 after steeping showing a slight lag compared with the development of (1→3,1→4)-β-glucanase activity. The levels of endoxylanase activity were different between the cultivars. For example, at day 4, which would be a suitable endpoint for malting of good quality cultivars, total endoxylanase activities of Static and Chariot malts were twice that of Hart and Optic. This variation in level of endoxylanase between cultivars did not correlate with the content of water extractable arabinoxylans in hot water extracts of the malts. However, those cultivars that accumulated most water extractable arabinoxylan had a different set of endoxylanase isoforms. This suggests that expression of specific endoxylanase isoforms may influence the extent of arabinoxylan solubilisation and/or degradation.The β-xylosidases and α-arabinosidases increased from low levels after steep to a plateau of activity at day 6 or 7 of germination. Total xylosidase was always higher than the arabinosidase activity. There were differences between cultivars but these were small compared with the variation in endoxylanase activity. (1→4)-β-d-Endomannanase activity was detected in all four cultivars at 2 days germination then rose to a maximum around 5 days.     

Dephytinization of wheat bran by fermentation with bakers' yeast,incubation with barley malt flour and autoclaving at different pH levels

Wheat bran is an important source of dietary fiber but also contains considerable amounts of phytic acid, which is known to impair mineral absorption. The present study was conducted to investigate the phytic acid reduction in coarse and fine wheat bran by fermentation with the different levels of bakers' yeast (3, 6 and 9%) for 8 h at 30 °C, incubation with the different levels of barley malt flour (2.5, 5.0, 7.5 and 10.0%) for 8 h at pH 5.2 and 55 °C, and autoclaving at the different pH levels (pH 5.0, 4.5, 4.0 and 3.5) adjusted with acetic acid for 2 h. The phytic acid content of the wheat bran was effectively reduced by all treatments, and the phytic acid lost was in the range of 88.4–96.9%. Without addition of yeast or malt flour, or autoclaving without pH adjustment, the phytic acid content of the bran samples was reduced at most to 44.9% of the initial amounts under the investigated conditions. Increasing the concentration of yeast or malt flour or decreasing the pH towards 3.5 did not enhance the phytic acid reduction. The most reduction occurred after 2 h of yeast fermentation and malt flour incubation, and after 30 min of autoclaving, which made up 92–98% of the total phytic acid loss. Extending the treatment periods contributed nominally to further increase in the phytic acid reduction, and the rate of the phytic acid loss decreased progressively.     

Rice varietal difference in sheath blight development and its association with yield loss at different levels of N fertilization

Variety and nitrogen (N) fertilizer input are the two main factors that influence the development of sheath blight (ShB) caused by Rhizoctonia solani in intensive and high-input rice (Oryza sativa L.) production systems. This study was conducted to determine the varietal difference in ShB development and its association with yield loss across N rates. Two indica inbred and two indica/indica F₁ hybrid varieties were grown under 0 and 90 kg N ha⁻¹ in 2003 wet season (WS) and under 0, 75, 145, and 215 kg N ha⁻¹ in 2004 dry season (DS). Inoculation was done in 3.2 m² in each experiment unit to achieve uniform disease development. Disease intensity was quantified by measuring relative lesion height (RLH) and ShB index (ShBI) of inoculated 10 hills at flowering and 14 days after flowering. Plant traits, grain yield, temperature, and relative humidity inside the canopy were also measured. Consistent and significant varietal differences in ShB intensity were observed across N rates in both WS and DS. Among the four varieties, IR72 and IR75217H had higher RLH and ShBI than PSBRc52 and IR68284H at all N rates. Sheath blight index at 14 days after flowering had the closest correlation with yield loss from ShB. Varieties with taller stature, fewer tillers, and lower leaf N concentration such as IR68284H generally had lower RLH and ShBI, and consequently lower yield loss from the disease. Disease intensity and yield loss from ShB increased with increasing N rates, but the magnitude of yield loss varied among varieties. This suggests that fertilizer N should be managed more precisely and differently for varieties with different plant type in order to reduce the disease development and maximize grain yield in the irrigated rice systems.     

Variation in the levels of the different xylanase inhibitors in grain and flour of 20 French wheat cultivars

A xylanase from Aspergillus aculeatus (glycoside hydrolase family 10), uninhibited by TAXI, and a xylanase from Bacillus subtilis (family 11), uninhibited by XIP-I, were selected to quantify the respective apparent levels of XIP-I and TAXI inhibitors, in flours and grains of 20 wheat varieties. The apparent TAXI amount ranged from 0.05 to 0.19 mg/g in flour (mean: 0.11 mg/g) and from 0.07 to 0.2 mg/g in grain (mean: 0.14 mg/g). The range observed for XIP-I was 0.12–0.6 mg/g in flour (mean 0.32 mg/g), and 0.21–0.56 mg/g in grain (mean: 0.41 mg/g). The inhibition profile of the xylanase from A. aculeatus by a crude inhibitor preparation suggested the presence of an additional component in wheat flour, responsible for an increase in inhibition.     

Yield and land-use efficiency of a cassava/cowpea intercropping system grown at different phosphorus rates

Cassava (Manihot esculenta Crantz) is frequently intercropped with cowpea [Vigna unguiculata (L.) Walp subsp. unguiculata] in the tropics. Little is known about the influence of P fertilization practices on the efficiency of land use and yields in cassava/cowpea intercropping systems. Two experiments were conducted on a Typic Dystropept soil with the objective of determining the influence of P application rate on yield and P status of cassava and cowpea grown in sole and intercropping systems, and the influence on land use efficiency. Cassava yields averaged across P rates were reduced 29% from the 28 Mg ha⁻¹ sole crop yield when intercropped with cowpea in 1979–1980. Cowpea yields were reduced by 19–38% from a sole crop yield of 1522 kg ha⁻¹ when intercropped in 1979, and 29–38% from a sole crop yield of 1277 kg ha⁻¹ in 1980. The rate of P application had little influence on cassava yield, except in 1981 when intercropped cassava yields were greater than 40 Mg ha⁻¹. In 1981, increasing the rate of P application from 0 to 44 kg ha⁻¹ resulted in a cassava yield increase from 41 to 47 Mg ha⁻¹. In 1979 and 1980, increasing the rate of P application from 0 to 22 kg ha⁻¹ increased cowpea yield 44 and 92%, respectively, while increasing P rate from 66 to 132 kg ha⁻¹ increased cowpea yield 28 and 18%, respectively. In 1981 and 1982, increasing the rate of P application from 0 to 44 kg ha⁻¹ increased cowpea yield by 1052 kg ha⁻¹. Phosphorus concentration of cassava and cowpea leaf blades increased with increases in rate of P application from 66 to 132 kg ha⁻¹ in 1979 and 1980, and from 0 to 44 kg ha⁻¹ in 1981 and 1982. Intercropping cassava with cowpea resulted in a 30% increase in land-use efficiency when no P was applied, while land-use efficiencies resulting from intercropping were increased by 41–50% with P application rates of 22–132 kg ha⁻¹. Cassava proved to be well-adapted to low-P soils and very competitive even without P application, whereas cowpea required the addition of P for adequate growth and yield. High productivity and a good competitive balance between the two crops were reached with only 22 kg ha⁻¹ of P, showing the great potential of cassava/cowpea intercropping on acid, infertile soils in the tropics.     

不同生态条件下大麦品种的适应性研究

通过对引自黑龙江、四川和河南等地的13份大麦品种材料进行试种,观察这些大麦在黔中地区自然生态条件下和盆栽条件下的生长发育特性和农艺性状表现。结果显示,所有参试品种材料都能完成生长发育的各个阶段,在大麦物候期和主要农艺性状上,不同品种材料间存在着明显的差异,方差分析均达极显著水平(p<0.000 1)。在供试大麦的产量构成上,13份材料中其千粒重超过50 g的有一半以上,仅3份材料的千粒重不足45 g。同时,播期、栽培方式和环境条件等对引种大麦生长的影响极显著,物候期与农艺性状以及农艺性状间存在显著斯皮尔曼秩相关性。综合分析表明,在黔中生态气候条件下,13份省外大麦品种材料均能正常生长,且具有良好的生态适应性,从而为进一步筛选出综合性状优良的大麦品种,培育能适应在贵州种植的大麦新品种提供依据。     

The competitive ability of pea-barley intercrops against weeds and the interactions with crop productivity and soil N availability

Grain legumes, such as peas (Pisum sativum L.), are known to be weak competitors against weeds when grown as the sole crop. In this study, the weed-suppression effect of pea-barley (Hordeum vulgare L.) intercropping compared to the respective sole crops was examined in organic field experiments across Western Europe (i.e., Denmark, the United Kingdom, France, Germany and Italy). Spring pea (P) and barley (B) were sown either as the sole crop, at the recommended plant density (P100 and B100, respectively), or in replacement (P50B50) or additive (P100B50) intercropping designs for three seasons (2003-2005). The weed biomass was three times higher under the pea sole crops than under both the intercrops and barley sole crops at maturity. The inclusion of joint experiments in several countries and various growing conditions showed that intercrops maintain a highly asymmetric competition over weeds, regardless of the particular weed infestation (species and productivity), the crop biomass or the soil nitrogen availability. The intercropping weed suppression was highly resilient, whereas the weed suppression in pea sole crops was lower and more variable. The pea-barley intercrops exhibited high levels of weed suppression, even with a low percentage of barley in the total biomass. Despite a reduced leaf area in the case of a low soil N availability, the barley sole crops and intercrops displayed high weed suppression, probably because of their strong competitive capability to absorb soil N. Higher soil N availabilities entailed increased leaf areas and competitive ability for light, which contributed to the overall competitive ability against weeds for all of the treatments. The contribution of the weeds in the total dry matter and soil N acquisition was higher in the pea sole crop than in the other treatments, in spite of the higher leaf areas in the pea crops.     

不同大豆品种在酸性红壤和石灰性土壤上耐低磷能力的差异

研究不同耐低磷大豆品种在酸性红壤和石灰性土壤上的耐性变化。结果表明,大豆品种的耐低磷能力与土壤类型有一定关系,干物质积累量和磷积累量的大豆品种×土壤类型间交互作用极显著。在酸性低磷红壤上,大豆品种湘春９１—１００、涟源泥冬黄豆和浙春２ 号的干物质量和磷积累量都显著高于桂阳傲泉黄豆和湘豆３ 号。在石灰性土壤上,干物质表现为湘春９１—１００、涟源泥冬黄豆＞ 桂阳傲泉黄豆、浙春２ 号＞ 湘豆３ 号,而磷积累量除湘春９１—１００ 显著较高外,其它４ 个品种间无显著差异。土壤类型对大豆品种的根系生长有较大影响     

Effect of different soil tillage and organic fertilizers on winter triticale and spring barley stem base diseases

Multi-factor crop management field experiments were conducted in Vezaiciai, in southwestern Lithuania, from 2004 to 2006 to assess the influence of tillage and organic fertilizer management on stem base disease development. The treatments included 4-year crop rotations of continuous grass, winter triticale, winter oilseed rape and spring barley in combination with three tillage systems (shallow (8–10 cm) non-ploughing tillage, shallow (10–12 cm) tillage and deep (20–25 cm) ploughing). Eyespot prevailed both in winter triticale and spring barley crops. Winter triticale was more susceptible than spring barley. Shallow tillage decreased eyespot incidence and severity relative to deep tillage. Crop residue management exerted a weak but statistically significant effect on the disease development on triticale; in general, slightly higher numbers of affected stems were recorded in triticale plots where the straw from the previous crop had been removed prior to planting. However, complete straw removal from plots significantly decreased eyespot severity in comparison with crop residue or manure management treatments in spring barley. The highest number of affected triticale and barley plants was found in shallow (10–12 cm) tillage plots. The effects of residue management on minimising eyespot severity can be expected only after a delay of a few years.     

施肥方式对玉米－大豆套作体系氮素吸收利用效率的影响

通过田间试验探讨了A1（N,210kg•hm-2）、A2（N,270kg•hm-2）、A3（N,330kg•hm-2）3种施氮水平和距窄行玉米0cm(B1)、15cm(B2)、30cm(B3)、45cm(B4) 4种施肥距离对玉米——大豆套作体系氮素吸收利用效率的影响。结果表明,与习惯施氮（A3）相比,减量施氮（A1、A2）提高了大豆R2、R5期单株根瘤数、根瘤干重和根瘤固氮潜力,以距玉米15cm处施肥的根瘤固氮能力较强;玉米、大豆的籽粒产量、地上部植株氮素吸收量和氮肥利用率随施氮量的增加呈先增加再降低的趋势,以A2处理的最高;施肥距离过大和过小均不利玉米、大豆产量的提高和氮素的吸收利用,以距玉米15~30cm处施肥效果最佳;减量施氮18%（A2）时,B2、B3处理相对常规穴施（B1）处理,玉米、大豆及玉米－大豆系统的籽粒产量、植株氮素吸收量、氮肥利用率和土壤总氮含量均显著提高,土壤氮素贡献率显著降低。