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81.
An experiment was performed to examine the chemical and biological effects on high clay sodic subsoil following the incorporation and incubation with organic amendments. The main treatments consisted of amendments with wheat shoots, lucerne pellets and peat, and these were compared to gypsum addition. Additional treatments were residues of chickpea and canola, chicken manure and sawdust. All materials were finely ground and added to crushed and sieved soil at the rate of 1% by weight. Wheat, canola and chickpea residues and chicken manure resulted in modest reductions in soil sodicity. Carbon and N mineralization were related to the soluble C/total N ratio in the amendment. The initial mineralization of wheat amendment was rapid due to its soluble C content, but then slowed to have the lowest loss, of around one third of added C, of all the plant residues after 174 days. In comparison, lucerne-amended soil increased total N and lost almost half of its C after the 174-day incubation. The canola stubble amendment showed the highest carbon loss, losing 64% of its added C. The addition of gypsum resulted in high soil electrical conductivity which suppressed respiration, compared to the control soil, indicating a detrimental effect on microbial activity due to the high electrolyte concentration in the soil. The peat amendment, with a low-soluble C content, showed a similar respiration rate to the control soil, confirming that a source of soluble C is important for the initiation of rapid biological activity. Soil pH was significantly increased (by 0.6 of a pH unit) with addition of chicken manure, and still remained higher than control soil after 174 days of incubation. Lucerne was the only plant residue to increase soil pH, with the effect being sustained for 56 days. The study demonstrated how some organic amendments can improve chemical fertility and biological activity in high clay sodic subsoil, and at the same time contribute, after 25 weeks incubation, to an increase in carbon content. 相似文献
82.
Shinsuke Yamanaka Ikuo Nakamura Hirokazu Nakai Yo-Ichiro Sato 《Genetic Resources and Crop Evolution》2003,50(5):529-538
The direct ancestor of rice (Oryza sativa L.) is believed to be AA genome wild relatives of rice in Asia. However, the AA genome wild relatives involve both annual and perennial forms. The distribution of the retrotransposon p-SINE1-r2, a short interspersed nuclear element (SINE) at the waxy locus was analyzed in diverse accessions of the AA genome wild relatives of rice (O. rufipogon sensu lato). Most annual wild rice accessions had this retrotransposon, while most perennial types lacked this element, contradicting results to the previous studies. Results presented here suggest that O. sativa has dual origin that lead to indica-japonica differentiation. Results suggest the indica line of rice varieties evolved from the annual genepool of AA genome and the japonica varieties from the perennial genepool of AA genome wild rice. 相似文献
83.
A greenhouse experiment was conducted with a specially designed apparatus consisting of an upper and lower chamber where the treatment with rice was carried out (treatment 1). The apparatus also had a single chamber where treatment 2, without rice plants, was carried out. The scope of this study was to elucidate the influence of rice plant growth on gaseous N losses as N2 and N2O produced by nitrification-denitrification in a flooded soil fertilized with (NH4)2SO4 (with 56.50 atom% 15N). Gas samples were withdrawn weekly and analyzed for (N2 + N2O)-15N losses by mass spectrometer and for N2O by gas chromatograph. The gaseous (N2 + N2O)-15N losses of the treatment with rice plants were significantly (P =0.01) higher than those of the treatment without rice plants, as were the amounts of N2O emitted. Rice plants facilitate the efflux of N2 and N2O from soil to atmosphere, as about half of the total gaseous 15N loss as N2 and N2O was found in the upper chamber. The proportion of N2O-15N to (N2 + N2O)-15N in the upper chamber was 10.56%, much higher than that of the lower chamber in treatment 1 and the headspace of treatment 2. 相似文献
84.
Within different land‐use systems such as agriculture, forestry, and fallow, the different morphology and physiology of the plants, together with their specific management, lead to a system‐typical set of ecological conditions in the soil. The response of total, mobile, and easily available C and N fractions, microbial biomass, and enzyme activities involved in C and N cycling to different soil management was investigated in a sandy soil at a field study at Riesa, Northeastern Germany. The management systems included agricultural management (AM), succession fallow (SF), and forest management (FM). Samples of the mineral soil (0—5, 5—10, and 10—30 cm) were taken in spring 1999 and analyzed for their contents on organic C, total N, NH4+‐N and NO3—‐N, KCl‐extractable organic C and N fractions (Corg(KCl) and Norg(KCl)), microbial biomass C and N, and activities of β‐glucosidase and L‐asparaginase. With the exception of Norg(KCl), all investigated C and N pools showed a clear relationship to the land‐use system that was most pronounced in the 0—5 cm profile increment. SF resulted in greater contents of readily available C (Corg(KCl)), NH4+‐N, microbial biomass C and N, and enzyme activities in the uppermost 5 cm of the soil compared to all other systems studied. These differences were significant at P ≤ 0.05 to P ≤ 0.001. Comparably high Cmic:Corg ratios of 2.4 to 3.9 % in the SF plot imply a faster C and N turnover than in AM and FM plots. Forest management led to 1.5‐ to 2‐fold larger organic C contents compared to SF and AM plots, respectively. High organic C contents were coupled with low microbial biomass C (78 μg g—1) and N contents (10.7 μg g—1), extremely low Cmic : Corg ratios (0.2—0.6 %) and low β‐glucosidase (81 μg PN g—1 h—1) and L‐asparaginase (7.3 μg NH4‐N g—1 2 h—1) activities. These results indicate a severe inhibition of mineralization processes in soils under locust stands. Under agricultural management, chemical and biological parameters expressed medium values with exception for NO3—‐N contents which were significantly higher than in SF and FM plots (P ≤ 0.005) and increased with increasing soil depth. Nevertheless, the depth gradient found for all studied parameters was most pronounced in soils under SF. Microbial biomass C and N were correlated to β‐glucosidase and L‐asparaginase activity (r ≥ 0.63; P ≤ 0.001). Furthermore, microbial biomass and enzyme activities were related to the amounts of readily mineralizable organic C (i.e. Corg(KCl)) with r ≥ 0.41 (P ≤ 0.01), suggesting that (1) KCl‐extractable organic C compounds from field‐fresh prepared soils represent an important C source for soil microbial populations, and (2) that microbial biomass is an important source for enzymes in soil. The Norg(KCl) pool is not necessarily related to the size of microbial biomass C and N and enzyme activities in soil.<?show $6#> 相似文献
85.
Benjamin Trost Annette Prochnow Michael Baumecker Andreas Meyer-Aurich Katrin Drastig Frank Ellmer 《Archives of Agronomy and Soil Science》2013,59(5):569-580
The aim of this study was to investigate the effect of supplemental irrigation on the amount of N2O emissions on a sandy soil in north-east Germany. N2O flux measurements were carried out over two vegetation periods from the emergence of plants to harvest. The level of N2O emissions was low, which is typical for sandy soils in north-east Germany. In both periods, irrigation had no increasing effect on N2O emissions. Relevant factors were the soil temperature and the soil water-filled pore space (WFPS), which were mainly influenced by weather conditions. This may indicate that nitrification was the main source of N2O emissions. In conclusion, this study has confirmed that sandy soils under weather conditions of north-east Germany generally have a very low potential for N2O emissions. 相似文献
86.
Dalila Souguir Howaida Ibrahim Abd-Alla Ezzedine El Ferjani Mohamed Larbi Khouja Mohamed Hachicha 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(8):688-696
Salt stress is more and more becoming a serious problem in the world especially if we consider its damaging effect on the plant growth and yield. The cultivation of medicinal plants, such as Aloe vera, might be an alternative for the saline water use and salt-affected soils occupation. Aloe vera, commonly known as aloe, is one of the primary medicinal plants with multipurpose applications going from pharmaceutical to cosmetic aspects with a promising economic return. Aloe plants were cultivated and irrigated, for 14 months, with drinking water (C0) and with two levels of salt (C1 and C2). Changes in growth, hydrogen peroxide (H2O2), lipid peroxidation and phenolic compounds were examined in leaves at harvest. Depressive effects of salt irrigation on the plant growth parameters and a perturbation in inorganic ion contents were found especially with a high level of salt in the irrigation water. The intracellular oxidative stress was evaluated with the H2O2 production. Our results showed that the H2O2 content increased with the accumulation of the toxic ion (Na) in the leaf tissues. In addition, lipid peroxidation, measured by the malondialdehyde (MDA) level, increased as well with salt augmentation in the irrigation water. In response to salt stress, Aloe leaves showed a significant increase in the levels of phenolic compounds too. These results suggest that Aloe can be planted in soils affected by salinity and irrigated with salt water at least at a moderate concentration used in the present study. 相似文献
87.
N2O是重要的温室气体,了解福建省农业生态系统N2O排放情况及其年代变化规律,对于寻找减排的技术路线与对策,进而实现全国的控制目标有重要意义。本研究基于福建省农业活动水平数据,采用区域氮素循环模型IAP-N方法,估算1991—2010年福建省农业生态系统氧化亚氮(N2O)的排放量(以纯氮量计)并分析其排放特征。结果表明:(1)1991—2010年福建省农业生态系统N2O排放总量(包括农田直接、间接排放,田间秸秆燃烧排放,粪便管理系统排放)呈先增加后降低趋势,从1991年的23 675.3 t·a–1增加到2006年的32 610.4t·a–1,之后降低至30 810.7 t·a–1(2010年)。1991—1995年、1996—2000年、2001—2005年、2006—2010年农业生态系统年平均N2O排放量分别为26 170.7 t·a–1、29 870.0 t·a–1、32 085.8 t·a–1、31 287.6 t·a–1。各类型排放量大小依次为:农田直接(66.2%)-粪便管理系统(20.7%)-农田间接(12.9%)-田间秸秆燃烧(0.2%)。(2)1991—2010年,农田N2O直接排放量呈先增加后降低趋势,从1991年的15 108 t·a–1增加到2006年的21 547 t·a–1,之后下降到2010年的20 594 t·a–1。4个时期年平均N2O直接排放量分别为17 073.0 t·a–1、19 976.8 t·a–1、21 183.4 t·a–1、20 778.6 t·a–1。农田旱作(包括蔬菜地、非蔬菜旱地、水旱轮作的旱季)N2O排放占农田N2O直接排放量的83.0%~90.7%,是农田直接排放的关键源。(3)1991—2010年间,福建省粪便管理系统N2O排放量保持在5 213.2~6 988.0 t·a–1,变化较稳定。粪便管理系统N2O排放的关键源为猪,占粪便管理系统N2O排放量的57.4%~67.9%。(4)2010年,农业生态系统N2O排放高值区主要分布在漳州市、南平市、泉州市和宁德市,其N2O排放量均在4 000 t·a–1以上,占全省总排放量的61.7%,应优先考虑削减这些地区的N2O排放。研究结果为决策者合理利用肥料,制定福建省农业生态系统温室气体减排措施提供科学依据。 相似文献
88.
89.
《中国兽医学报》2016,(3):490-495
旨在研究钼镉联合诱导对麻鸭肾功能及肾脏中Bcl-2基因mRNA表达量的影响。选用360羽健康的11日龄江南2号麻鸭并随机分成6组,每组60只(公母各30羽)。(NH_4)_6Mo_7O_(24)·4H_2O和3CdSO_4·8H_2O分别作为本试验的钼源和镉源,在每千克基础日粮中添加不同剂量的Mo、Cd,各组的处理情况分别为:对照组(Mo 0 mg,Cd 0mg)、低钼组(Mo 15 mg,Cd 0 mg)、高钼组(Mo 100 mg,Cd 0 mg)、镉组(Mo 0 mg,Cd 4 mg)、低钼镉组(Mo 15mg,Cd 4mg)、高钼镉组(Mo 100mg,Cd 4mg)。试验期120d。在试验期第30、60、90、120天时采集血样分离血清用于检测血清中Cr、UA、BUN、Na~+、K~+、Cl-、Mg~(2+)的含量;于60、120d采集鸭肾组织检测Bcl-2 mRNA的表达量。结果显示,120d高钼镉组Cr和BUN显著高于对照组(P0.05);120d试验组血清中UA低于对照组但差异不显著(P0.05);120d试验组血清Na~+、Cl-显著低于对照组(P0.05);试验组血清K~+低于对照组但差异不显著(P0.05);90、120d高钼组和高钼镉组的血清Mg~(2+)显著低于对照组(P0.05);在60、120d,除低钼组外,其余试验组鸭肾中Bcl-2mRNA表达量均极显著低于对照组(P0.01),高钼镉组极显著高于其他组(P0.01);钼镉联合组变化比单独组更显著。此结果表明钼、镉及其联合诱导可导致麻鸭肾功能损伤、肾脏中Bcl-2 mRNA表达量下调,且钼镉呈协同作用。 相似文献
90.