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1.
Abstract

Leaf N and soil nitrate and ammonium levels were monitored in 1986 and 1987 following N fertilization of 8–9 year old highbush blueberries. Urea was applied at 76 kg N/ha in a single application at bud break or in two applications (split) at bud break and petal fall. Controlled release fertilizers (CRF), of two different residual effects (Osmocote 3 mo., Osmocote 8 mo.) were applied at 38 kg N/ha or 76 kg N/ha at bud break. Compared to controls, N applications increased soil ammonium and nitrate levels early in the season and leaf N levels throughout the season. Urea provided a greater increase in leaf N and soil ammonium levels than CRF. Split urea applications increase leaf levels slightly over single urea treatments. Fertilizers increased soil ammonium and nitrate levels below the root zone, indicating that some leaching losses occurred.  相似文献   

2.
The amounts of P applied cumulatively to a neutral arable soil (pH 7.1–7. in 0.01M CaCl2) at Rothamsted, as farmyard manure, alone or with superphosphate, which were converted to organic P in 100 years ranged from 18 to 44 μg P/g of soil (0–23 cm). Superphosphate alone (3300 kg P/ha) slightly lessened the total organic P in the soil. Neither farmyard manure nor super-phosphate significantly changed the amounts (38 to 42 μg P/g) of inositol penta- and hexaphosphate in these soils. In the surface layers (0–7.5 cm) of soils from permanent grassland at Rothamsted, superphosphate (3370kg P/ha) increased organic P by 134 μg P/g at pH 4.5 and 19 μg P/g at pH 6.5, about 6 and 1 per cent respectively of the P remaining from superphosphate applied cumulatively since 1858. In the sub-surface layers (7.5–23 cm) superphosphate increased organic P by 93 μg P/g at pH 4.5 and 62 μg P/g at pH 6.2, about 18 and 10 per cent respectively of the P remaining from superphosphate. The sum of inositol penta- and hexaphosphates accounted for 32 per cent at pH 4.5 and 21 per cent at pH 6.5 of the increases in organic P in the surface layers and 45 per cent and 26 per cent in the sub-surface layers at pH 4.5 and 6.5 respectively. Superphosphate (1260–2100 kg P/ha) applied intermittently or cumulatively increased total organic P by 19 to 52 μg P/g and inositol penta- and hexaphosphates by 13 to 17 μg P/g in acid tea soils (pH 3.2–3.4) from Georgia, U.S.S.R. Rock phosphate (510–1020kg P/ha) applied cumulatively had no effect on either the total organic P or the inositol P in acid tea soils (PH 3.6–3.7) from Ceylon.  相似文献   

3.
《Journal of plant nutrition》2013,36(9):1445-1455
The larval stage of the spotted cucumber beetle (Diabrotica vigifera zeae), the Mexican corn rootworm, is a highly devastating pest of cornfields in Texas and the Southwest. A systemic organophosphate insecticide, standard release terbufos (ST), applied in row with the corn seed at planting, has been termed effective in reducing crop damage from the Mexican corn rootworm. However, recent field observations have indicated possible association of micronutrient deficiency symptoms with use of terbufos and over-the-top sulfonyl urea herbicides (nicosulfuron, primisulfuron) on crops such as corn. This experiment was conducted to determine if this systemic soil insecticide would affect plant metabolic activities as measured by nutrient deficiency chlorosis and plant growth. The study also involved testing a controlled release terbufos (CR) version of the same insecticide. Each soil insecticide was compared with and without foliar treatments with one of the sulfonyl urea herbicides (nicosulfuron) used in controlling grass-type weeds in corn. The greenhouse study was conducted on a Monteola sandy clay loam (Typic Pellusterts), which is a typical soil used in corn production in southern Texas. Standard release (ST) and CR forms of terbufos were compared at the label recommended rate (1.1 kg a.i./ha) and also at 2 kg a.i./ha. All materials were banded in the seed row at planting. Treatments were arranged in a randomized block design with three replications. Early visual chlorosis ratings (7 days) and chlorophyll readings at 28 days indicated increased interveinal chlorosis with soil insecticide applications. Plants overcame these early effects with time and showed higher chlorophyll than untreated plants at 42 days. Depressed early plant growth and reduced tissue levels of certain micronutrients indicated these systemic insecticides both with and without over-the-top herbicide could be injurious during early stages of plant growth. However, the affected plants were able to overcome most of the effects later in the growing season. Tissue iron (Fe) concentrations were slightly reduced by terbufos alone and reduced further when nicosulfuron was applied. Zinc was reduced substantially by terbufos but appeared to not change when the over-the-top herbicide was included.  相似文献   

4.
Urea, labelled with15N, was applied, at rates equivalent to 0–400 kg N ha?1, to mixed L + F horizon soil materials from a jack pine (Pinus banksiana Lamb.) forest. The L + F materials were held at 13°C and 33 kPa moisture in three experiments lasting from 6 to 128 days. In the first experiment the immobilization of fertilizer N was determined, in the second the stimulation of microbial activity was measured, and in the third urea reactions in a forest floor without microorganisms were examined. Urea stimulated microbial activity and microbial mineralization of soil N. Total amounts of N immobilized and recovered as organic N, after 128 days, increased with rate of application from 50 to 400 kg urea-N ha?1. The pH and C contents of water extracts of soil increased with increasing rates of urea application. Organic matter in a forest floor treated with urea was shown to solubilize after microbial activity was inhibited by gamma radiation, and this suggests that chemical C release was brought on by the urea. Results from this study were consistent with the hypothesis that microbial activity in urea-treated soil is stimulated by increased availability of C in soil.  相似文献   

5.
In temperate grassland, urea has been shown to have lower nitrous oxide emissions compared to ammonium nitrate‐based fertilizer and is less expensive. However, nitrogen (N) loss via ammonia volatilization from urea raises questions regarding yield performance and efficiency. This study compares the yield and N offtake of grass fertilized with urea, calcium ammonium nitrate (CAN) and urea treated with the urease inhibitor N‐(n ‐ butyl) thiophosphoric triamide (NBPT) at six site‐years. Five annual fertilizer N rates (100–500 kg N/ha) were applied in five equal splits of 20–100 kg N/ha during the growing season. On average, urea produced slightly better yields than CAN in spring (103.5% of CAN yield) and slightly poorer yields in summer (98.4% of CAN yield). There was no significant difference in annual grass yield between urea, CAN and urea + NBPT. Urea had the lowest cost per tonne of DM grass yield produced. However, the urea treatment had lower N offtake than CAN and this difference was more pronounced as the N rate increased. There was no difference in N offtake between urea + NBPT and CAN. While this study shows that urea produced yields comparable to CAN, urea apparent fertilizer N recovery (AFNR) tends to be lower. Urea selection in place of CAN will increase national ammonia emissions which is problematic for countries with targets to reduce ammonia emissions. Promisingly, NBPT allows the agronomic performance of urea to consistently equal CAN across N rates by addressing the ammonia loss limitations of urea.  相似文献   

6.
Abstract

The effectiveness of Dwell, a nitrification inhibitor, was tested in a greenhouse with two fertilizers and three Arizona soils. Tomato plants (Lycopersicum esculentum Mill., cv. Row Pak) were grown in ABS plastic columns 10 cm diameter and 50 cm long containing 4500 g soil. Urea and ammonium sulfate (AS) were applied at 112 and 224 kg N/ha and Dwell (5‐ethoxy‐3‐trichloromethyl‐l,2,4‐thiadiazole) was applied at rates of 0 and 1.27 kg/ha of active ingredient. Both fertilizers and Dwell were added by mixing uniformly or in a band. Dwell increased ? uptake by 41%. The highest ? uptake was with Dwell with the highest urea rate, but Dwell was effective with both fertilizers in all soils. The lowest response to Dwell was with AS‐Laveen loam treatment, whereas the highest response, but the lowest ? uptake, was with urea ‐ Vinton loamy sand treatment. Dwell did not affect the inorganic‐N contents of the soils.  相似文献   

7.
稻田控释氮肥的施用效果与合理施用技术   总被引：26，自引：7，他引：26  
选用新型控释氮肥(LP)5个类型,采用其不同用量和组合,在南方典型双季稻区第四纪红壤发育的水稻土上进行早稻和晚稻的一次性基肥试验。结果表明,施用不同控释氮肥,稻田表层土和表面水的NH4+-N含量极显著地低于常规氮肥(尿素);控释肥的氮素释放过程与水稻吸氮过程基本一致。控释氮肥用量以N75kg/hm2较适宜,其用量比尿素N150kg/hm2相比仍可维持高产;早稻施用控释氮肥,可成功地实现施肥、播种、抛秧的一次性技术配套与结合,减轻劳动强度,适当提高种植密度有利于高产;晚稻采用条施的方法可显著地提高产量。与尿素N150kg/hm2比较,早稻选用控释氮肥LPS40或LPS60较好;晚稻选用LP70和LPS80并按LP70(50%)+LPS80(50%)的比例搭配,有利于水稻生长发育和维持高产。控释氮肥具有缓释作用,其供应氮素持久;LPS40和LPS60用量N150kg/hm2且高密度栽培时有一定的后效,可分别提高再生稻产量10%和16%。  相似文献   

8.
Urea is a common fertilizer in delayed‐flood rice production in the United States, and its use worldwide has increased dramatically in recent decades. This study aimed to directly quantify urea‐N persistence in floodwater and soil used for rice production. We conducted a set of three laboratory experiments to investigate urea‐N presence in the floodwater and soil. Untreated urea was applied to dry or wet soil and flooded immediately or urea treated with the urease inhibitor N‐(n‐butyl)‐thiophosphoric triamide (NBPT), or untreated urea was applied to dry soil and flooded after a 5‐day delay. Urea‐N was analysed colorimetrically (using the microplate‐adapted, diacetyl monoxime method) in the floodwater, and at 2‐cm intervals in soil after 10‐cm long, silt‐loam soil columns were flooded for 12, 24, 48 and 96 h. The only management practice that led to insignificant urea‐N concentrations in floodwaters was the application of urea followed by a 5‐day delay before flooding. Urea‐N can persist in floodwaters for an estimated 98 and 120 h after immediately flooding dry‐soil‐applied or wet‐soil‐applied untreated urea, respectively. Urea‐N concentrations in floodwaters were up to 33 times less when dry‐soil‐applied than wet‐soil‐applied. Average NBPT‐treated urea‐N concentrations in soil ranged up to 63 mg/kg after 24 h of flooding and were <1 mg/kg after 96 h of flooding. The 5‐day delay resulted in ≤1 mg urea‐N/kg soil when untreated urea was applied. Generally, the threat of N entering adjacent waterways in the form of urea is likely to be limited because of its short‐term persistence (≤120 h) in rice floodwater.  相似文献   

9.
At Chainat, in the central plain of Thailand, where problems of double cropping are being investigated, a growth rate and nitrogen uptake rate for maize of 370 and 3.15 kg/ha/ day respectively were obtained. In one season there was a high positive correlation between maximum nitrogen yield and maize grain yield.When 15N-labelled (NH4)2SO4 nitrogen was applied to maize at 100 kg/ha of N, 49 per cent could be recovered in tops after 12 weeks. After 8 weeks, 23 per cent was in the soil organic N plus roots, and after 12 weeks had decreased to 10 per cent. In the same period, the unaccountedfor fertilizer N had increased from 27 per cent at 8 weeks to 41 per cent at 12 weeks.In a long term rotation experiment involving 18 dry and wet season cropping combinations, a provisional balance sheet after two years indicates (1) that the soil nitrogen status can be maintained with the introduction of high input, dry season upland crops into a cropping system where wet season rice is grown only, (2) that in the absence of nitrogen fertilizer about 40 kg/ha of N is added per season to the soil-plant system under rice, and (3) that mung bean (Phaseolus aureus) fixes between 58 and 107 kg/ha of N per season.  相似文献   

10.
Laboratory incubation experiments were conducted with uncoated urea or urea coated with dementholized oil (DMO), pitch (the mint oil discard), terpenes (the products of menthol mint oil), or dicyandiamide (DCD) to study the retardation of urea hydrolysis and nitrification in soil. Two levels (0.5 and 1 %) of coating were tested. Urea was applied at a rate of 200 mg kg−1 of dry weight of soil. The urea hydrolysis and nitrification processes were inhibited by all three natural products. All the three natural products viz., DMO, terpenes, and pitch significantly retarded urease activity of soil.  相似文献   

11.
Field experiments on cotton with different forms of urea applied at rates of 40 and 80 kg N/ha were carried out. The results indicated that application of nitrogen increased plant height, dry matter accumulation, number of bolls per plant, seed cotton yield and nitrogen uptake. The proportion of dry matter and nitrogen in the stem was increased and that in the leaves was reduced by N application. Sulphur coated urea (all applied at sowing) was about the same in effect as N-Serve treated urea and gave significantly more seed cotton yield than untreated urea, neem cake treated urea and sulphur coated urea (applied in two splits). Nitrogen efficiency as expressed by kg seed cotton production per kg N applied was greater with 40 kg N/ha rate than with 80 kg N/ha. Sulphur coated urea (all applied at sowing) gave the highest nitrogen efficiency followed by N-Serve treated urea.  相似文献   

12.
表施尿素的冬小麦土壤氨挥发损失   总被引：22，自引：0，他引：22  
Ammonia volatilization was measured with a continuous air flow enclosure method from a winter wheat field in the Experimental Farm of Jurong Agricultural School to investigate its main influencing factors. The experiment with five treatments in triplicate, no N (control), 100, 200 and 300 kg N ha-1 with rice straw cover at a rate of 1 500 kg ha-1 and 200 kg N ha-1 without rice straw, started when the winter wheat was sown in 1994. Sixty percent of the total amount of N applied was basal and 40% was top-dressed. The measurement of ammonia volatilization was immediately conducted after urea was top-dressed on soil surface at wheat elongation stage in spring of 1996 and 1997. The results showed that there was a diurnal variation of ammonia volatilization rate from the winter wheat field, which synchronized with air temperature. N losses through ammonia volatilization increased with increasing N application rate, but the ratio of N lost through ammonia volatilization to applied N was not significantly affected by N application rate. The coverage of rice straw had no significant effect on ammonia volatilization. Soil moisture and rain events after urea was top-dressed affected ammonia volatilization significantly.  相似文献   

13.
The influence of 5 and 50 mg active ingredient kg-1 soil of nine preemergence and nine postemergence herbicides on transformations of urea N in soil was studied in samples of two coarse-textured and two fine-textured soils incubated aerobically at 20°C. The effects of each herbicide on soil urea transformations was measured by determining the amounts of urea hydrolyzed and the amounts of NO inf3 sup- and NO inf2 sup- produced at various times after treatment with urea. Applied at the rate of 5 mg active ingredient kg-1 soil, none of the herbicides retarded urea hydrolysis in the four soils used, but four of the postemergence herbicides (acifluorfen, diclofop methyl, fenoxaprop ethyl) retarded urea hydrolysis in the two coarse-textured soils. All the herbicides tested except siduron retarded nitrification in the two coarse-textured soils when applied at 50 mg of urea N active ingredient kg-1 soil, and fenoxaprop ethyl and tridiphane markedly retarded nitrification of urea N in all four of the soils when applied at this rate. One-way analysis of variance and correlation analyses indicated that the inhibitory effects of the 18 herbicides tested on nitrification of urea N in soil increased with a decrease in the organic-matter content and an increase in the sand content of the soil. Present address: Department of Soil and Environmental Sciences, University of California, Riverside, CA 92521, USA  相似文献   

14.
Abstract

The effects of ammonium sulfate and urea nitrogen (150 kg N/ha) applied with three levels (5, 10 and 15% of N) of the nitrification inhibitors karanjin and nitrapyrin on grain protein of rice (Oryza sativa L. cv. Bala) were studied in pot experiment. Karanjin at the 10 and 15 per cent levels and nitrapyrin at the 10 per cent level significantly increased grain protein. Rice protein levels were highest at the 15 per cent karanjin level.  相似文献   

15.
Abstract

NPK was applied to a Haynie, very fine, sandy loam as 89.6 MT/ha (40 T/ac) of OF (organic fertilizer as feedlot manure at 45% water content) and as MF (mineral fertilizer) with nutrients equivalent to the manure during 18 months.

Organic fertilizer increased soil organic matter content 0.25% more than the MF and 0.2% more than the control. Organic fertilizer increased the CEC 0.3 m.e./100 g more than the MF and 0.4 m.e./100 g more than the control. Organic fertilizer increased exch. Mg by 32 kg/ha while MF decreased exch. Mg slightly.  相似文献   

16.
The nitrogen balance of native and applied nitrogen is discussed for three regions in northern Australia. The problems of estimating the nitrogen addition of legumes to the soil-plant system at Katherine (14°28'S) are discussed in terms of changes in nitrate concentration in the subsoil, and the contribution of nitrogen in rainwater to the system. Legumes like Townsville stylo and guar can contribute up to 90 kg/ha of nitrogen per season. Only under grazing conditions is the soil organic nitrogen increased with Townsville stylo.On the sub-coastal plains near Darwin (12°33'S) labelled fertilizer nitrogen losses under flooded rice conditions vary from 37 to 94 per cent depending on fertilizer type and mode of application. Considerable amounts of fertilizer nitrogen were found in the flood-water up to 2 weeks after application. Surface broadcasting increased immobilization of fertilizer as compared with deep placement.At the Ord River valley (15°39'S) with cotton crops, high apparent recoveries of urea and other nitrogen fertilizers are obtained (up to 64 per cent) with high nitrogen applications (225 kg/ha) by banding the fertilizer at sowing at 1 m spacing at 15 cm depth.  相似文献   

17.
柴达木农田土壤Cd的积累影响及风险预测   总被引：1，自引：0，他引：1  
【目的】土壤重金属空间结构特征是土壤环境质量评价及重金属污染评价的基础。本文用地质统计学方法研究了柴达木盆地原生地和耕种50年的农田土壤镉的空间分布特征,对土壤镉进行质量评价,同时分析了农业耕种对土壤镉积累的影响,调查统计了灌溉水、肥料、农药等农业源土壤镉的输入量,为农田镉积累的风险预测提供参考。【方法】以柴达木盆地诺木洪农场的一块原生地（从未耕种过的土地,可以认为无化肥污染）和一块耕种地（已种植了50年的农田）为研究对象,从原生地采集22个土壤样本,耕种地采集50个土壤样本进行镉含量的测定,同时检测灌溉水、农药、化肥中的镉含量,并进行每年农田输入量的统计。用Excel软件进行数据处理,反比权重法（IDW,Inverse Distance Weighting）插值,GIS9.3进行空间分析和图像处理;以单项污染指数法评价土壤镉质量,评价模式为Pi=Ci/Si（Pi为污染物镉的单项污染指数,Ci为污染物镉的实测数据,Si为污染物的评价标准）。评价标准分别以农业部公布的行业标准《无公害食品 枸杞生产技术规程》（NY/T 5249-2004）和《绿色食品 枸杞》（NY/T1051-2006）产地环境标准要求下的《绿色食品 产地环境技术条件》（NY/T 391-2000）为依据。依据农业源土壤镉输入量,以土壤现状值为起点,以绿色食品标准限量值为终点,测算输入量积累突破两端差值的年限。【结果】原生地22个土壤样品的镉平均含量为0.30 mg/kg,是土壤背景值的两倍（0.14 mg/kg）,达到无公害食品（0.60 mg/kg）和绿色食品（0.40 mg/kg）标准;种植50年农田的50个土壤样品的镉平均含量为0.43 mg/kg,是土壤背景值的3倍,达到无公害食品标准,但超过绿色食品标准。用于灌溉的河水的镉含量为0.0036 ng/kg。检测生产中使用的15种农药和7种肥料,其中的镉导致每年土壤镉增加3444 mg/hm2。最严重的污染源是鸡粪,施入土壤后每年导致土壤镉增加2025 mg/hm2,其次依次为复合肥（使土壤镉增加576 mg/hm2）,磷酸二铵（增加432 mg/hm2）,有机肥（增加360 mg/hm2）。【结论】以小尺度空间分布和全量统计研究的诺木洪农场土壤镉含量这一单一指标衡量,可以看出诺木洪原生地土壤是清洁的,能够满足无公害、绿色食品的生产;但是研究选择的多年耕种田已经遭到重金属镉的污染,只能达到无公害食品标准,而达不到绿色食品标准。现行生产中的施肥措施是导致诺木洪土壤重金属镉污染的一个重要因素,其中鸡粪对镉污染的贡献最大,其次是复合肥、磷酸二铵和有机肥。如果继续现在这种耕种方式,以现有的原生地镉含量均值为0.30 mg/kg进行计算,76.3年后该土地镉含量将超过0.40 mg/kg的绿色标准上限。  相似文献   

18.
A study of the leaching losses of P and S from a sandy loam and a fine sandy clay loam, using undisturbed cores of surface soil was undertaken. These cores were treated individually with Aerophos X, gypsum and granulated superphosphate at the rate of 20 kg P/ha, 20 kg S/ha and 200 kg/ha (approx. 18 kg P/ha and 22 kg S/ha), respectively.A total of 20–30% P was leached from the Aerophos-treated cores after 500 ml of leachate had been collected. The rate of P leached was high in the initial fractions, but decreased steadily in subsequent leachates. Losses of S from gypsum treated cores was 40–70% of the total amount applied, but the leaching pattern was similar to that found for P. For the superphosphate-treated cores, smaller nutrient losses per unit P and S applied were noted. The relative solubilities of the various fertilizers may account for these differences.Greater losses of P and S were recorded for the sandy loam because this soil is probably less able to fix these nutrients.  相似文献   

19.
延迟释放型包衣尿素对水稻生长和氮素吸收的影响   总被引：19，自引：0，他引：19  
通过田间试验比较研究了普通尿素和延迟释放型包衣尿素在不同施用量、不同施肥方式(普通尿素为基肥+两次追肥;延迟释放型包衣尿素为接触施肥方式)条件下对移栽稻生长过程和氮素吸收的影响。结果表明,延迟释放型包衣尿素在比普通尿素施氮量(N150kg/hm2)减少30%(N105kg/hm2)和50%(N75kg/hm2)时,对水稻生长不会产生任何不良影响;由于包衣尿素在田间的养分释放动态与水稻对氮素的吸收规律吻合,施用包衣尿素的水稻产量、吸氮量和氮肥利用率均显著高于普通尿素处理,其中水稻产量增加12.7%～14.4%,吸氮量增加27.5%～32.7%;普通尿素和氮肥用量减少30%和50%的包衣尿素3个处理的氮肥利用率分别为19.9%、58.8%和89.9%。此外,施用包衣尿素比普通尿素水稻的子粒粗蛋白质含量提高9.2%～12.2%。  相似文献   

20.
The effects of 20 herbicides on denitrification of nitrate in three soils were studied by determining the effects of 10 and 50μgg?1 soil of each herbicide on the amounts of nitrate lost and the amounts of nitrite, N2O and N2 produced when soil samples were incubated anaerobically after treatment with nitrate. The herbicides used were butylate, EPTC, chlorpropham, propham, diuron, linuron, monuron, siduron, alachlor, trifluralin, 2,4-D amine, 2,4-D ester, atrazine, cyanazine, metribuzin, simazine, dalapon, chloramben, dicamba and dinoseb.None of the herbicides studied significantly affected denitrification of nitrate when applied at the rate of 10 μg g?1 soil, but dinoseb increased the ratio of N2 to N2O in the gaseous products of denitrification when applied at this rate. Butylate, EPTC, diuron, simazine and dalapon had no significant effect on denitrification when applied at the rate of 50μgg?1 soil, whereas metribuzin and dinoseb enhanced denitrification when applied at this rate. The influence of the other herbicides on denitrification when applied at the rate of 50μgg?1soil depended on the soil, but all enhanced or inhibited denitrification in at least one soil.  相似文献   

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