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1.
《Communications in Soil Science and Plant Analysis》2012,43(3-4):171-181
Abstract Although it has been shown that the nitrogen (N) concentration of winter wheat (Triticum aestivum L. em Thell) at Feeke's growth stage 5 (GS 5) can be used to assist in making more accurate spring N fertilizer recommendations, the need remains to find a more convenient and accurate means for predicting N fertilizer needs of wheat. We conducted seven N fertilizer response experiments over two years in central and southeastern Pennsylvania to determine if chlorophyll meter readings of wheat leaves at GS 5 could predict whether a significant, positive grain yield response to N fertilizer would be obtained. The chlorophyll meter readings at GS 5 were more accurate (correctly predicting response to N fertilizer in 24 of 25 treatments for a 4% error rate) than GS 5 plant N concentration (20% error rate). There were too few treatments with a positive response to N fertilizer to be able to determine if chlorophyll meter readings could be used to accurately predict N fertilizer rates needed for economic optimum yield. 相似文献
2.
The ability of a hand‐held chlorophyll meter (SPAD‐502 Chlorophyll Meter3, Minolta Camera Co., Ltd., Japan) to determine the N status of cotton (Gossypium hirsutum L.) was studied at field sites in Alabama and Missouri. Meter readings on the uppermost fully‐expanded leaf were compared to leaf‐blade N and petiole NO3‐N at first square, first bloom and midbloom as to their seed cotton yield predictive capability. Nitrogen was applied at rates of 0, 45, 90, 135, 180 and 225 kg ha‐1 to establish a range of cotton chlorophyll levels, tissue N concentrations, and seed cotton yields. A typical curvilinear cotton yield response to N fertilizer was observed in Alabama experiments. Because of adverse weather conditions, cotton yield in Missouri experiments did not respond to N. Chlorophyll meter readings were significantly correlated to leaf‐blade N concentration at all three stages of growth for all experiments. In Alabama, chlorophyll meter readings compared favorably to leaf‐blade N and petiole NO3‐N with respect to their seed cotton yield predictive capability at all three stages of growth. It appears that hand‐held chlorophyll meters would be as reliable as leaf‐blade N and petiole NO3‐N for predicting supplemental N fertilization requirements of cotton. However, more research will be required prior to use of chlorophyll meter readings for routine cotton‐N recommendation purposes. 相似文献
3.
《Communications in Soil Science and Plant Analysis》2012,43(3-4):353-363
Abstract Irrigation of untilled orchard floors can lead to substantial leaching losses of nitrate‐nitrogen (NO3‐N). Soil NO3 that remains after cool weather in the fall is subject to leaching in the spring. Nitrate losses can be controlled through growing ground cover vegetation to cycle residual nitrogen (N) and/or limiting the amount of water applied. A study was initiated in lysimeters to compare sodded soil surfaces versus bare soil for controlling NO3 leaching losses. Cool season vegetation (orchardgrass, western wheatgrass, white clover) and warm season grasses (bahiagrass and buffalograss) were compared for then‐effect on grapefruit seedling growth. A field verification in pecan orchards was conducted where clean‐till versus a grass soil cover was used to compare the relative movement of NO3 through the profile. The presence of vigorously growing sods greatly reduced NO3 losses the first year in the lysimeter study. The second year a shade screen was placed over the lysimeters, resulting in greatly reduced cool season sod growth and substantially reduced warm season sod growth. The best grapefruit growth occurred on bare soil; vigorous sod growth greatly reduced grapefruit tree growth. In the second year of the experiment, tree growth on bare soil began to absorb substantial amounts of N. The presence of even reduced receding sod growth still adversely affected grapefruit tree growth. In commercial pecan orchards, NO3 distributions in a clean‐tilled orchard soil showed large quantities of NO3 entering the water table (the highest quantity at the lowest depth of the soil profile) while in the presence of a sod much less NO3 (highest profile NO3 near the soil surface) was being lost to the water table. However, the NO3 leaching patterns were of large leaching losses in clean tilled surfaces and small controlled leaching losses with sod surfaces. 相似文献
4.
《Communications in Soil Science and Plant Analysis》2012,43(7-8):687-697
Abstract Chlorophyll meter leaf readings were compared to grain yield, leaf N concentration and soil NH4‐N plus NO3‐N levels from N rate studies for dryland winter wheat Soil N tests and wheat leaf N concentrations have been taken in the spring at the late tillering stage (Feekes 5) to document a crop N deficiency and to make fertilizer N recommendations. The chlorophyll meter offers another possible technique to estimate crop N status and determine the need for additional N fertilizer. Results with the chlorophyll meter indicate a positive association between chlorophyll meter readings and grain yield, leaf N concentration and soil NH4‐N plus NO3‐N. Additional tests are needed to evaluate other factors such as differences among locations, cultivars, soil moisture and profile N status. 相似文献
5.
Leaf SPAD values are thought to be an indicator of potato nitrogen (N) status; however, when making plant N diagnosis, no single threshold leaf SPAD value can be used for all potato cultivars because of cultivar variation. We conducted field experiments over 3?years to test whether the difference in SPAD values between the upper and lower leaves was consistent among potato cultivars, and whether this value responded to N application levels. The results showed cultivar affects the SPAD values of the fourth and eighth leaves (SPADL4 and SPADL8), but not SPADL4-8, the difference between SPADL4 and SPADL8. Moreover, the SPADL4-8 values responded well to N application levels. Therefore the SPADL4-8 could be applied as a general index of N status across different potato cultivars, and establishing a threshold SPADL4-8 value might be more useful in guiding N fertilization recommendations for different potato cultivars. 相似文献
6.
Chengli Zhu Yaming Zhai Zhanyu Zhang Junyu Zheng Zongxiao Liu 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2017,67(5):474-484
The scarcity of good-quality water is forcing the use of brackish water for irrigation in many areas around the world. Alternate fresh- and brackish water irrigation is a feasible irrigation method (IM). A pot experiment was carried out with three brackish water IMs and at three levels (1, 3 and 5?g NaCl L?1). The various levels of brackish waters were irrigated at the seedling stage, the jointing and tasseling stage and the after tasseling stage, respectively. The responses of maize (Zea mays L.) to alternate irrigation were investigated through gas exchange and chlorophyll fluorescence. The results showed that the alternate use of fresh- and brackish water reduced the increasing soil salinity caused by brackish water irrigation. The changes in net photosynthesis rate (Pn), stomatal conduction (gs), intercellular CO2 concentration (Ci) and chlorophyll content (SPAD) values revealed that maize was more resistant to brackish water at the after tasseling stage. Moreover, significant reductions in maximum quantum yield (Φpo), effective quantum yield of photochemical energy conversion (Φ2), photochemical quenching (qp), non-photochemical quenching of variable chlorophyll fluorescence (qN) and non-photochemical chlorophyll fluorescence quenching (NPQ) of photosystem II, grain yield and biomass weight of maize subjected to high NaCl level brackish water at the jointing and tasseling stage were observed. This implied that maize plants were extremely sensitive to brackish water irrigation during the jointing and tasseling stage, and freshwater should be applied at this growth period. Our results would be helpful for sustainable maize production using alternate irrigation with fresh- and brackish water in arid and semi-arid areas. 相似文献
7.
《Soil Science and Plant Nutrition》2013,59(2):186-194
Abstract To determine the relationships between microbial biomass nitrogen (N), nitrate–nitrogen leaching (NO3-N leaching) and N uptake by plants, a field experiment and a soil column experiment were conducted. In the field experiment, microbial biomass N, 0.5 mol L?1 K2SO4 extractable N (extractable N), NO3-N leaching and N uptake by corn were monitored in sawdust compost (SDC: 20 Mg ha?1 containing 158 kg N ha?1 of total N [approximately 50% is easily decomposable organic N]), chemical fertilizer (CF) and no fertilizer (NF) treatments from May 2000 to September 2002. In the soil column experiment, microbial biomass N, extractable N and NO3-N leaching were monitored in soil treated with SDC (20 Mg ha?1) + rice straw (RS) at five different application rates (0, 2.5, 5, 7.5 and 10 Mg ha?1 containing 0, 15, 29, 44 and 59 kg N ha?1) and in soil treated with CF in 2001. Nitrogen was applied as (NH4)2SO4 at rates of 220 kg N ha?1 for SDC and SDC + RS treatments and at a rate of 300 kg N ha?1 for the CF treatment in both experiments. In the field experiment, microbial biomass N in the SDC treatment increased to 147 kg N ha?1 at 7 days after treatment (DAT) and was maintained at 60–70 kg N ha?1 after 30 days. Conversely, microbial biomass N in the CF treatment did not increase significantly. Extractable N in the surface soil increased immediately after treatment, but was found at lower levels in the SDC treatment compared to the CF treatment until 7 DAT. A small amount of NO3-N leaching was observed until 21 DAT and increased markedly from 27 to 42 DAT in the SDC and CF treatments. Cumulative NO3-N leaching in the CF treatment was 146 kg N ha?1, which was equal to half of the applied N, but only 53 kg N ha?1 in the SDC treatment. In contrast, there was no significant difference between N uptake by corn in the SDC and CF treatments. In the soil column experiment, microbial biomass N in the SDC + RS treatment at 7 DAT increased with increased RS application. Conversely, extractable N at 7 DAT and cumulative NO3-N leaching until 42 DAT decreased with increased RS application. In both experiments, microbial biomass N was negatively correlated with extractable N at 7 DAT and cumulative NO3-N leaching until 42 DAT, and extractable N was positively correlated with cumulative NO3-N leaching. We concluded that microbial biomass N formation in the surface soil decreased extractable N and, consequently, contributed to decreasing NO3-N leaching without impacting negatively on N uptake by plants. 相似文献
8.
9.
Bruna Pereira de Souza Felipe Paolinelli de Carvalho Marcelo Ehlers Loureiro Walas Permanhane Sturião 《Journal of plant nutrition》2020,43(16):2455-2465
AbstractThis research aims to evaluate the impact of nitrogen deprivation and water stress on gas exchange and chlorophyll fluorescence in young plants of five cultivars of Arabic coffee. A factorial experiment 5 (cultivars) × 3 (treatments: control without stress, water stress of ?1.5?MPa and stress of N – 0.0?mmol L?1 N) was carried out in a complete randomized block design with three replicates. Before being submitted to the treatments, the plants were grown in a greenhouse for 240?days, and then transferred to a growth chamber under controlled conditions. Subsequently, after the experimental period of 96?h we measured photosynthetic rate (A), stomatal conductance to water vapor (gs), transpiratory rate (E), internal and external carbon ratio (Ci/Ca), water use efficiency (A/E), electron transport rate (ETR), actual quantum yield of PS II electron transport (φFSII), and maximum photochemical efficiency of PS II (Fv/Fm). Water stress reduced A, gs, E, A/E, ETR, φFSII, and Fv/Fm. The nitrogen deficiency reduced ETR, φFSII, and Fv/Fm. Under short-term water stress Catuaí Vermelho maintain the A values due to better stomatal control, reduced water lost by transpiration (E) and better water use efficiency A/E, while Mundo Novo and Acauã show lower damage to Fv/Fm. Short-term nitrogen stress has low impact on A of young plants of Coffea arabica cultivars with adequate N-nutrition. 相似文献
10.
Abstract. The applicability of the 'threshold concentration' concept in formulating guidelines for irrigating with saline water was tested under field conditions on red-brown earths from different field experiments in south eastern Australia. Infiltration of water in the field and the effect of rainfall impact were studied using ring infiltrometers and a rotating-disc rainfall simulator.
Three threshold concentration lines relating sodium adsorption ratio (SAR) and total cation concentration (TCC) in soil extracts were tested. These lines were based on laboratory tests of soil permeability, spontaneous dispersion and mechanical dispersion. They were found to predict the infiltration problems due to rainfall impact under three different surface soil conditions - bare soil without cultivation, soil with no tillage and complete crop cover, and cultivated soils without any crop cover.
Infiltration rates in continuous pasture plots were predicted by the threshold concentration line of spontaneous dispersion except in a high salt treated soil where reduced plant growth affected evapotranspiration and water intake during infiltration. 相似文献
Three threshold concentration lines relating sodium adsorption ratio (SAR) and total cation concentration (TCC) in soil extracts were tested. These lines were based on laboratory tests of soil permeability, spontaneous dispersion and mechanical dispersion. They were found to predict the infiltration problems due to rainfall impact under three different surface soil conditions - bare soil without cultivation, soil with no tillage and complete crop cover, and cultivated soils without any crop cover.
Infiltration rates in continuous pasture plots were predicted by the threshold concentration line of spontaneous dispersion except in a high salt treated soil where reduced plant growth affected evapotranspiration and water intake during infiltration. 相似文献
11.
Fang Wang Ray R. Weil Lei Han Mingxin Zhang Zhaojun Sun 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2019,69(1):52-61
Forage radish is a unique winter cover crop that is relatively new but becoming rapidly adopted in temperate, humid North America. Little is known about how the use of this cover crop may influence subsequent nitrogen availability, soil water accumulation in the soil profile in corn silage production system. In this present work, the average nitrogen uptake by silage corn increased significantly by 11.6% in cover plots compared with the no-cover control plots. The recovery efficiency and agronomic efficiency of applied nitrogen in silage corn declined in cover plots compared to no-cover plots. The average soil water storage in cover plots was significantly higher than in the control after corn sowing and at the harvest stage. With increasing nitrogen application level, the average corn grain yield increased significantly at 56 and 112 kg N ha?1 by 13.1% and 39.8%, respectively. Planting a forage radish cover crop can facilitate growth of silage corn and markedly improve total nitrogen uptake of corn. Consideration should be given to nitrogen application rate and also to avoiding excessive nitrogen input in the subsequent crop following a cover crop, thereby truly improving subsequent fertiliser use efficiency. 相似文献
12.
13.
《Communications in Soil Science and Plant Analysis》2012,43(11-12):1183-1195
Abstract In our experiments, carbonated water (CW) modified the equilibria in soil. Application of CW decreased the soil pH about 1.5 units one hour after irrigation ended. Minimal, though well defined, differences in soil pH were observed between the two carbonated treatments. The same relationship between the treatments was not found in pH levels of the leachate. This seems strictly related to the temporal and spatial changes in the carbon dioxide (CO2) acidifying effect caused by chemical and biological factors as water descended the soil column. The temporary reduction in soil pH in the CW treatment induced the highest nutrient mobility for most of the elements. 相似文献
14.
M. Khoshravesh B. Mostafazadeh‐Fard S. F. Mousavi A. R. Kiani 《Soil Use and Management》2011,27(4):515-522
In arid and semi‐arid regions, farmers use low quality groundwater because of limited availability of high quality irrigation water; instead, magnetized water can be used for irrigation given its better quality. Magnetized water is obtained by passing water through permanent magnets or through electro‐magnets installed in or on a feeding pipeline. This study at the Gorgan Agricultural and Natural Resources Research Center, Gorgan province, Iran, investigated soil moisture distribution from trickle irrigation. Treatments were magnetic and non‐magnetic water and sub‐treatments involved the addition of 200 mg/L calcium carbonate and 400 mg/L calcium carbonate with well water providing the control. The experiment was laid out with a complete randomized block design with three replications. Soil moisture around the drippers was measured for 1, 2 and 3 days after irrigation during the 3‐month irrigation period. The results show that the differences in soil moisture for days 1, 2 and 3 after irrigation with magnetized irrigation water were lesser than those for the non‐magnetized irrigation water treatments. Irrigation with magnetized irrigation water caused higher soil moisture compared with the non‐magnetized irrigation water for different irrigation water salinities. The use of magnetized water for irrigation is recommended to improve irrigation efficiency. 相似文献
15.
Losses of nitrogen by denitrification from a grassland soil fertilized with cattle slurry and calcium nitrate 总被引:5,自引:0,他引:5
Losses of N by denitrification from an imperfectly drained grassland soil were measured by the acetylene-inhibition technique over a 1-yr period, during which applications of up to 200 kg ha ?1 of N as cattle slurry or calcium nitrate were made. The quantities of N lost from nitrate-treated soil were much greater than from slurry-treated areas, and ranged up to 21% of the N applied. The losses occurred predominantly over brief periods following fertilizer application in the spring. Ratios of N released as N2 to that released as N2O increased as denitrification rates increased. The highest ratio recorded, 24, may have been a conservative estimate because inhibition of N2O reduction may not have been complete on all occasions. Increased respiration was observed in the soil profile as a result of adding C2H2. This effect should be taken into account in interpreting experiments using the C2H2-inhibition technique. 相似文献
16.
Vertical water fluxes at the water table and in the subsoil need to be quantified because of their significance for the supply of water to crops and the control of soil salinization in areas with shallow groundwater. A soil–water–atmosphere–plant (SWAP) model was calibrated using measured values of soil water content and the water fluxes at the water table. The measurements were taken in a field experiment where the depth to groundwater and the volume of irrigation water applied were controlled. The calibrated SWAP model was then used to simulate the soil water content and fluxes at the water table and in the subsoil under different irrigation and groundwater conditions. The predicted values provided a quantitative insight into specific terms in the water balance equation together with soil water fluxes in the subsoil that cannot be measured directly by field instruments. Crops utilized significant amounts of water from deeper soil layers and directly from groundwater, when the volume of irrigation decreased and the depth to the water table was <3.0 m. Depth to the water table significantly influenced water fluxes occurring in the soil profile over the period when evaporation dominated the hydrological cycle. Shallow groundwater is a very significant water resource for meeting the water requirement of crops. In practice, the frequency and quantity of irrigation need to be varied according to groundwater conditions. 相似文献
17.
We investigated whether enhanced nitrogen (N) and water inputs would redistribute the microbial community within different soil aggregate size classes in a field manipulation experiment initiated in 2005. Distribution of microbial groups was monitored in large macroaggregates (>2000 μm), small macroaggregates (250–2000 μm), and microaggregates (<250 μm) in a semiarid grassland. Both arbuscular mycorrhizal (AM) fungi and saprophytic fungi were the most abundant in soil macroaggregates. The gram-negative bacteria were more abundant in soil microaggregates. Total phospholipid fatty acid (PLFA) concentration in general and actinomycetes in particular decreased with N addition under ambient precipitation but was unaffected by combined additions of N and water within the three soil aggregate fractions as compared to control plots. In contrast, the abundance of saprophytic fungi decreased with combined N and water addition, but it was not affected by N addition under ambient precipitation. The abundance of gram-positive bacteria increased with N addition under both ambient and elevated water conditions for all soil aggregate fractions. In summary, the higher short-term nutrient and water availabilities provoked a shift in soil microbial community composition and increased total PLFA abundance irrespectively of the level of soil aggregation. In the long term, this could destabilize soil carbon pools and influence the nutrient limitation of soil biota within different soil aggregate size classes under future global change scenarios. 相似文献
18.
Significant areas of temperate forests in Central Europe, NE America and E Asia receive high amounts of N deposition. According to the few studies available, suspension of the N load leads to reductions in both inorganic soil N and leaching of N within a few years. We report that, surprisingly, N is still mineralized at high rates 14 yr after suspension of a previous N-load of >100 kg N/ha yr for 20 yr. In this treatment, gross N mineralization rates exceeded those in control plots by a factor 3, but equaled those in still on-going (34 yr of) treatments with 30 and 60 kg N/ha yr, in which levels of extractable NH4+ were up to 10 times higher. 相似文献
19.
《Communications in Soil Science and Plant Analysis》2012,43(9-10):923-933
Abstract Microbial biomass is determined from the excess of extractable organic N released from fumigated soil samples. In the presence of relatively high contents of labeled mineral N, small differences in organic N and N may not be detectable. Two approaches were tested to determine organic N content and its N enrichment in the presence of considerably greater concentrations of labeled mineral N: (i) Removal of mineral N from mixed solutions of alanine and NH4 or NO3 by reduction and boiling under alkaline conditions, prior to Kjeldahl digestion. (ii) Including mineral N in Kjeldahl N analysis, by reduction under acidic conditions prior to digestion and calculating organic N and N content by subtracting mineral N and N. The removal of mineral N was either incomplete‐ particularly regarding labeled mineral N, or partly destroyed organic N as well. When mineral N was included in the digest, the recovery of N and 15N was sufficiently accurate to obtain good results of organic N and 15N by subtracting the known quantities of mineral N, even when organic N was only 20% of the total Kjeldahl N. This procedure was used to determine the flush of Kjeldahl N in fumigated soils that were incubated with labeled mineral N and cellulose. 相似文献
20.
Abstract. Monoculture winter barley was grown for 5 years with 80 or 160 kg/ha of fertilizer nitrogen (N) and established by either shallow cultivation (straw removed) or ploughing (straw incorporated) in a replicated 2 ± 2 split plot experiment. The lower N rate reduced average grain yield from 6.85 t/ha to 5.61 t/ha. The cultivation/straw disposal system had no effect on yield. Halving the N rate reduced the amount of N removed in the crop by an average of 40 kg/ha and reduced the amount of nitrogen leached by 11 kg/ha per year. Using a shallow cultivation system for crop establishment, following the removal of straw, initially reduced N leaching compared to ploughing in the straw, but in the later years of the experiment losses were similar. Over the five years the full N rate with ploughing system resulted in a small positive nitrogen balance of 66 kg/ha, but all other treatment combinations resulted in a negative balance. 相似文献