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1.
The effect of different fertilisation (i.e. broadcast application and fertigation) and irrigation practices (tank sprinkler and drip irrigation) on yield, yield quality (nitrate content), nitrogen uptake of white cabbage (Brassica oleracea var. capitata L.) and the potential for N losses was assessed on sandy-loam agricultural soil. 15N-labelled fertiliser was used as a tracer. It was found that different practices significantly affected yield, nitrate content in plants, N uptake, as well as fertiliser use efficiency. The highest yield (93 t ha−1), plant N uptake (246 kg ha−1), and fertiliser use efficiency (42%) were obtained under treatment with broadcast fertilisation with farmer's practice of irrigation (tank sprinkler). The N surplus after harvest was −41 kg N ha−1, indicating the lowest potential for N losses. Treatment by fertigation and drip irrigation covering 100% of the crop's water requirements did not result in the highest yield as expected (72 t ha−1), the N surplus after harvest was about +38 kg ha−1. The lowest yield (58 t ha−1), fertiliser use efficiency (30%) and hence the highest potential for N losses (N surplus after harvest +68 kg ha−1) were found in treatment with broadcast fertilisation and drip irrigation covering 50% of the crop's water requirements.  相似文献   

2.
Soils in central Florida citrus production region are very sandy, hence are vulnerable to leaching of soluble nutrients and chemicals. The objective of this study was to develop nitrogen (N) and irrigation best management practices for citrus in sandy soils to maintain optimal crop yield and quality, and to minimize N leaching below the rootzone. A replicated plot experiment was conducted in a highly productive 20+ year-old ‘Hamlin’ orange [Citrus sinensis (L.) Osbeck] trees on ‘Cleopatra mandarin’ [(Citrus reticulata Blanco)] rootstock grove located on a well drained Tavares fine sand (hyperthermic, uncoated, Typic Quartzipsamments) in Highland County, FL. Nitrogen rates (112–280 kg ha−1 year−1) were applied as fertigation (FRT), water soluble granular (WSG), a combination of 50% FRT and 50% WSG, and controlled release fertilizer (CRF). Tensiometers were used to monitor the soil moisture content at various depths in the soil profile as basis to optimize irrigation scheduling. Fruit yield and quality and nutritional status of the trees were reported in a companion paper. Soil solution was sampled at 60, 120, and 240 cm depths under the tree canopy using suction lysimeters. Concentrations of NO3-N in the soil solution at 240 cm deep, which is an indicator of NO3-N leaching below the tree rootzone, generally remained below the maximum contaminant limit (MCL) for drinking water quality (10 mg L−1) in most samples across all N sources and rates, but for few exceptions. Total N in the fruit was strongly correlated with fruit load, thus, at a given N rate N removal by the fruit was lower during years of low fruit yield as compared to that during the years of high fruit yield. Furthermore, there was a strong linear relation between N and K in the fruit. This supports the need to maintain 1:1 ratio between the rates of N and K applications. In a high fruit production condition, the N in the fruit accounted for about 45% of the total N input on an annual basis. Fifteen percent of the total N input at 280 kg N ha−1 year−1 was not accounted for in the citrus N budget, which could be due to leaching loss. This estimate of potential leaching was very close to that predicted by LEACHM simulation model. The improved N and irrigation management practices developed in this study contributed to an improved N uptake efficiency and a reduction in N losses.  相似文献   

3.
Elucidation of the effects of different quantities of nitrogen (N) and water applied through drip and furrow irrigation on fruit yield and water use efficiency (WUE) in eggplant is essential for formulating proper management practices for sustainable production. The present investigation was undertaken to evaluate the independent and interactive effects of four levels of N and different quantities of water applied through drip as well as furrow irrigation on eggplant fruit yield, agronomic efficiency of N and WUE. In the present field investigation, ridge planting with each furrow and alternate furrow irrigation were compared with drip irrigation at three levels of water: 100%, 75% and 50% of each furrow irrigation (designated as D1.0, D0.75 and D0.5). The four levels of N studied were 90, 120, 150 and 180 kg N ha−1 (designated as N90, N120, N150 and N180). The eggplant hybrid BH-1 was transplanted on August 5, 2004 at the spacing of 60 cm × 45 cm.  相似文献   

4.
Greenhouse field experiments on tomato were carried out at Shouguang, Shandong province, over four double cropping seasons between 2004 and 2008 in order to understand the effects of manipulating root zone N management (RN) on fruit yields, N savings and N losses under conventional furrow irrigation. About 72% of the chemical N fertilizer used in conventional treatment (CN) inputs could be saved using the RN treatment without loss of yield. The cumulative fruit yields were significantly higher in the RN treatment than in the CN treatment. Average seasonal N from irrigation water (118 kg N ha−1), about 59% of shoot N uptake, was the main nitrogen source in treatments with organic manure application (MN) and without organic manure or nitrogen fertilizer (NN). N losses in the RN treatment were lowered by 54% compared with the CN treatment. Lower N losses were found in the MN and NN treatments due to excessive inputs of organic manure and fruit yields were consequently substantially affected in the NN treatment. The critical threshold of Nmin supply level in the root zone (0–30 cm) should be around 150 kg N ha−1 for sustainable production. April to May in the winter–spring season and September to October in the autumn–winter season are the critical periods for root zone N manipulation during crop growth. However, control of organic manure inputs is another key factor to further reduce surplus N in the future.  相似文献   

5.
Elevated levels of nitrate-nitrogen (NO3-N) in the surficial aquifer above the drinking water quality standard, i.e. maximum contaminant limit (MCL; 10 mg L−1), have been reported in some part of central Florida citrus production regions. Soils in this region are very sandy (sand content >95%), hence are vulnerable to leaching of soluble nutrients and chemicals below the rooting depth of the trees. The objective of this research was to develop N and irrigation best management practices for citrus in sandy soils to maintain optimal crop yield and quality, and to minimize potential leaching of nitrate below the root zone. Six years of field experiment was conducted in a high productive (mean fruit yield > 80 Mg ha−1yr−1) >20-year-old ‘Hamlin’ orange trees [Citrus sinensis (L.) Osbeck] on ‘Cleopatra mandarin’ (Citrus reticulata Blanco) rootstock grown on a well drained Tavares fine sand (hyperthermic, uncoated, Typic Quartzipsamments) in Highland county, FL. Nitrogen rates ranged from 112 to 280 kg ha−1 yr−1 applied as fertigation (FRT), water soluble granular (WSG), 50:50 mix of FRT and WSG, and controlled-release fertilizer (CRF). Tensiometers were used to monitor the soil water content as a basis to schedule optimal irrigation. Fruit yield response over the entire range of N rates was greater for the FRT and WSG sources as compared to that for the WSG + FRT or CRF sources. Using the regression analysis of the fruit yield in relation to N rate, the optimum N rate appeared to be at 260 kg ha−1 yr−1. Based on fruit production response in this study, the N requirement for production of 1 Mg of fruit varied from 2.2 to 2.6 kg across four N sources. This study demonstrated an increased N uptake efficiency, as a result of best management of N and irrigation applications. The optimal N and K concentration in the 4–6-month-old spring flush leaves were 26–30, and 15–18 g kg−1, respectively. However, fruit yield response showed no significant relationship with concentrations of P in the 4–6-month-old spring flush leaves over a range of 0.8–2.4 g kg−1. The results of fate and transport of N in soil and in soil solution with application of different rates and sources of N, and components of citrus tree N budget, are reported in a companion paper.  相似文献   

6.
In order to establish a rational nitrogen (N) fertilisation and reduce groundwater contamination, a clearer understanding of the N distribution through the growing season and its dynamics inside the plant is crucial. In two successive years, a melon crop (Cucumis melo L. cv. Sancho) was grown under field conditions to determine the uptake of N fertiliser, applied by means of fertigation at different stages of plant growth, and to follow the translocation of N in the plant using 15N-labelled N. In 2006, two experiments were carried out. In the first experiment, labelled 15N fertiliser was supplied at the female-bloom stage and in the second, at the end of fruit ripening. Labelled 15N fertiliser was made from 15NH415NO3 (10 at.% 15N) and 9.6 kg N ha−1 were applied in each experiment over 6 days (1.6 kg N ha−1 d−1). In 2007, the 15N treatment consisted of applying 20.4 kg N ha−1 as 15NH415NO3 (10 at.% 15N) in the middle of fruit growth, over 6 days (3.4 kg N ha−1 d−1). In addition, 93 and 95 kg N ha−1 were supplied daily by fertigation as ammonium nitrate in 2006 and 2007, respectively. The results obtained in 2006 suggest that the uptake of N derived from labelled fertiliser by the above-ground parts of the plants was not affected by the time of fertiliser application. At the female-flowering and fruit-ripening stages, the N content derived from 15N-labelled fertiliser was close to 0.435 g m−2 (about 45% of the N applied), while in the middle of fruit growth it was 1.45 g m−2 (71% of the N applied). The N application time affected the amount of N derived from labelled fertiliser that was translocated to the fruits. When the N was supplied later, the N translocation was lower, ranging between 54% at female flowering and 32% at the end of fruit ripening. Approximately 85% of the N translocated came from the leaf when the N was applied at female flowering or in the middle of fruit growth. This value decreased to 72% when the 15N application was at the end of fruit ripening. The ammonium nitrate became available to the plant between 2 and 2.5 weeks after its application. Although the leaf N uptake varied during the crop cycle, the N absorption rate in the whole plant was linear, suggesting that the melon crop could be fertilised with constant daily N amounts until 2–3 weeks before the last harvest.  相似文献   

7.
Fertigation has the potential to reduce extra chemical load by improving nutrient and water use efficiency of coconut (Cocos nucifera L.), but studies demonstrating the fertilizer reduction through drip irrigation in comparison to conventional ring basin method are rare in the Eastern Indo-Gangetic Plains (IGP) of South Asia. A long-term field experiment was conducted during 2007–2013 in West Bengal, India, to study the effect of fertigation on coconut var. DXT. The experiment was laid out in a randomised complete block design (RCBD) with six treatments (control – no fertilizers and water applied with drip irrigation; 25%, 50%, 75% and 100% of the recommended dose of fertilizer (RDF), each applied with drip irrigation; and 100% of the RDF and water applied with ring basin method of irrigation (i.e., conventional method)). Nuts yield was significantly higher for 75% of RDF (24.44 t ha?1 year?1) followed by 100% of RDF, each drip irrigation (23.79 t ha?1 year?1) compared to control (21.89 t ha?1 year?1). Copra yield was significantly higher for 75% of RDF (3.19 t ha?1) compared to 100% of RDF (3.12 t ha?1) and no fertilizer (1.87 t ha?1). Nitrogen (N), phosphorus (P) and potassium (K) contents of soil increased by 4.9%, 10.4% and 9.4%, respectively, with 75% of RDF applied through drip irrigation. Microbial population showed inverse relationship with amount of fertilizer application. The most water-use efficient fertigation treatment was 75% RDF (13.48 kg copra m?3) followed by 100% RDF (13.18 kg copra m?3) with drip irrigation as compared to conventional way soil application of fertilizers through ring basin method of irrigation (4.23 kg copra m?3). Role of N on yield variability was most prominent by both available soil N status (R2 = 0.49**) and leaf N concentration (R2 = 0.51**). The study indicated that there is a great scope for reducing the N, P and K fertilizers by up to 25% of the present RDFs for coconut when applied through drip irrigation compared to ring basin method of irrigation for its higher productivity and profitability through efficient use of nutrients and water in the Eastern IGP of South Asia.  相似文献   

8.
The effects of different irrigation regimes on yield and quality of green beans (Phaselous vulgaris L.) irrigated with a drip irrigation system under field conditions in the Mediterranean region of Turkey were evaluated along two years. Irrigation regimes consisted of four irrigation intervals based on four levels of cumulative pan evaporation (Epan) values (I1: 15; I2: 30; I3: 45 and I4: 60 mm); irrigations occurred on the respective treatments when Epan reached target values, and three plant–pan coefficients as for irrigation levels (Kcp1 = 0.50, Kcp2 = 0.75 and Kcp3 = 1.00). Irrigation intervals varied from 2 to 4 days in I1, 5 to 7 days in I2, 8 to 10 days in I3 and 10 to 12 days in I4 treatments in 2004 and 2005 growing seasons Both irrigation levels and intervals significantly affected the green bean yields. Maximum and minimum yields were obtained from the I1Kcp3 and I4Kcp1 treatments as 24,320 and 14,200 kg ha−1 in the first, and 23,850 and 13,210 kg ha−1 in the second experimental year, respectively. As the Kcp value decreased the total yields in each irrigation interval also decreased. However, with the longer irrigation interval (I4), lower yields were obtained with all Kcp coefficients. Seasonal water use (ET) values in the treatments varied from 276 mm in I4Kcp1 to 400 mm in I1Kcp3 in the first experimental year, and from 365 mm in I4Kcp1 to 472 mm in I1Kcp3 in the second experimental year. Significant linear relations were found between green bean yield and seasonal ET for each experimental year. Irrigation intervals resulted in similar water use in the treatments with the same Kcp value. Water use efficiency (WUE) and irrigation water use efficiency (IWUE) values were significantly influenced by the irrigation intervals and plant–pan coefficients. WUE ranged from 4.33 kg m−3 in I4Kcp3 to 6.08 kg m−3 in I1Kcp3 in 2004, and varied from 3.62 kg m−3 in I4Kcp1 to 5.43 kg m−3 in I2Kcp2 in the 2005 growing season. Maximum IWUE was observed in I2Kcp1 (6.16 kg m−3), and minimum IWUE was in I4Kcp3 treatment (3.83 kg m−3) in the experimental years. Both irrigation levels and irrigation frequencies had significantly different effects on quality parameters such as fresh bean length, width, number of seed per pod and 100 fresh bean weights. In conclusion, I1Kcp3 irrigation regime is recommended for field grown green beans under the Mediterranean conditions in order to attain higher yields with improved quality.  相似文献   

9.
Onion yield and quality response to two irrigation scheduling strategies   总被引：1，自引：0，他引：1  
Irrigation technologies that conserve water are necessary to assure the economic and environmental sustainability of commercial agriculture. This study was conducted in the Rio Grande Valley in Texas to evaluate yield and quality of subsurface drip irrigated onions (Allium cepa L.) using different scheduling strategies and water stress levels. One strategy consisted of initiating irrigation when the reading of a granular matrix sensors (Watermark® 1 soil moisture sensor, Irrometer, Co., Riverside, CA) installed at 0.2 m depth reached −20 kPa (optimum), −30 kPa and −50 kPa. The second strategy was to replace 100%, 75%, and 50% of crop evapotranspiration (ETc) weekly. Higher total yields, and jumbo onion size yields were obtained when the soil moisture was kept above −30 kPa. Yields were not affected when water applications were reduced from 100% to 75% ETc and from −20 to −30 kPa. The ETc strategies of 100%, and 75% ETc resulted in similar water usage to the soil moisture monitoring strategies of initiating irrigation at −20 and −30 kPa. Total yields dropped significantly when soil water stress increased below −50 kPa. For the ET based strategy yields also dropped with the 50% ETc treatment. Onion bulb pungency and brix were unaffected by water level.  相似文献   

10.
Studies were conducted to observe the effect of different soil moisture and nutrient regimes on postharvest attributes of onion irrigated with microsprinkler irrigation system under semi-arid climate for 3 consecutive years (2002–2004). Soil moisture regime consisted of four irrigation treatments based on pan evaporation replenishment (0.60, 0.80, 1.00 and 1.20 Ep). Similarly, three fertigation treatments were tried with nutrient application rates of 100 (50:25:25), 150 (75, 37.5, 37.5) and 200 (100:50:50) kg/ha of NPK. Irrigation and fertigation had marked effect on yield, postharvest attributes and storability of onion. Irrigation at 1.20 Ep and fertigation at 200 kg/ha produced higher bulb and dry matter yield, mean bulb size and weight, which decreased with the decrease in amount of irrigation and fertigation. The percentage of B-grade bulbs, which is considered commercially important, had been considerably higher at 1.20 Ep of irrigation and 200 kg/ha of fertigation. TSS increased up to 1.00 Ep and then declined slightly, whereas it varied with fertigation significantly. A decreasing trend for protein content was recorded with the increase in irrigation from 0.60 to 1.20 Ep, however, protein content increased with increase in fertigation. Irrigation at 0.80 Ep and fertigation @ 200 kg/ha resulted into minimum physiological loss in weight (%) for onion during 60 days of storage. But for extended storage period, increasing fertigation and decreasing irrigation had adverse effect on storability of bulbs. Theoretically, 416 mm irrigation water was found optimum for maximizing the dry matter yield of onion. Studies indicated that onion crop should be irrigated at 1.0 Ep under microsprinkler irrigation regime for better postharvest attributes. Similarly, fertigation @ 150 kg/ha is most desirable for micro sprinkler irrigated onion crop under semi-arid climate of India.  相似文献   

11.
In conservation tillage systems based on legume mulches it is important to optimize N management strategies. The present study evaluated the effect of some winter legume cover crops converted into mulches on the following no-tillage tomato (Solanum Lycopersicum L.) yield, tomato nitrogen uptake, tomato use efficiency (NUE), soil nitrate and the apparent N remaining in the soil (ARNS) in a Mediterranean environment. Field experiments were carried out from 2002 to 2004 in a tomato crop transplanted into: four different types of mulches coming from winter cover crops [hairy vetch (Vicia villosa Roth.), subclover (Trifolium subterranem L.), snail medic (Medicago scutellata L. Miller), and Italian ryegrass (Lolium multiflorum Lam.)]; a conventional tilled soil (CT); and a no-tilled bare soil (NT). All treatments were fertilized with three different levels of nitrogen (N) fertilizer (0, 75, and 150 kg N ha−1). Cover crop above-ground biomass at cover crop suppression ranged from 4.0 to 6.7 t ha−1 of DM and accumulated from 54 to 189 kg N ha−1, hairy vetch showed the highest values followed by subclover, snail medic and ryegrass. The marketable tomato yield was higher in no-tilled legume mulched soil compared to no-tilled ryegrass mulched soil, CT, and NT (on average 84.8 vs 68.7 t ha−1 of FM, respectively) and it tended to rise with the increase of the N fertilization level. A similar trend was observed on tomato N uptake. Hairy vetch mulch released the highest amount of N during tomato cultivation followed by subclover, snail medic, and ryegrass (on average 141, 96, 90 and 33 kg N ha−1). The tomato NUE tended to decrease with the increase of the N fertilization rates, it ranged from 39 to 60% in no-tilled legume mulched soil and from −59 to 30% in no-tilled ryegrass mulched soil when compared to the CT. The soil NO3-N content and the ARNS was always higher in the soil mulched with legumes compared to the soil mulched with ryegrass and in NT and CT. This study shows that direct transplanting into mulches coming from winter legume cover crops could be useful for improving the yield and the N-uptake in a no-tillage tomato crop. Furthermore, considering the high N content in the upper soil layer and the remaining N content in the organic mulch residues after tomato harvesting, there is a large amount of N potentially available which could be immediately used by an autumn–winter cash crop.  相似文献   

12.
Summary

Two field experiments during 1996-98 at Bangalore, India studied the effect of soil moisture regimes (0.3, 0.6 and 0.9 IW:CPE ratios) irrigation water cumulative pan evaporation (IW:CPE) ratios and three levels of nitrogen application (0,100 and 200 kg ha–1). Another experiment investigated three irrigation levels (0.3, 0.6 and 0.9 IW:CPE ratios), two levels of nitrogen application (100 and 200 kg ha–1) and organic mulch (0 and 5 t ha–1) on oil content, herbage, oil yield and quality of geranium grown on alfisols. Soil moisture maintained at 0.6-0.9 IW:CPE ratios significantly increased both the herbage and oil yields of geranium. Application of 200 kg N ha–1 gave maximum herbage and oil yield compared with those obtained from 0 and 100 kg N ha–1. Organic mulch increased the oil yield of geranium. The concentration and quality of essential oil were not influenced either by soil moisture regime, N rates or organic mulch.  相似文献   

13.
Effects of the commercial product TrichoFlow WP™ (Agrimm Technologies Ltd., New Zealand), based on the fungus Trichoderma harzianum, on quality characteristics and yield of bulb onion was investigated. Bulb sets of the local cultivar Kantartopu was planted in soil with in and between row distances of 0.15 m and 0.40 m, respectively. The product, at considerably high dosages of 5 g m−2, 10 g m−2 and 15 g m−2, was mixed with water and sprinkled once to the plots at planting. Analyses of data at harvest did not show statistical significance for Trichoderma effect on total bulb yield, bulb diameter, leaf length, number of shoot apex, %titratable acidity, number of internal (fleshy) leaves, number of external (papery) leaves, %soluble solids and %bulbs with diameters of 20–39 mm, 40–69 mm and ≥70 mm. The yields obtained from the plots treated with the dosages of 5 g m−2, 10 g m−2 and 15 g m−2 and the control plots were 1063.7 kg da−1, 1051.0 kg da−1, 1066.5 kg da−1 and 985.0 kg da−1, respectively. Our results showed that high dosages of the Trichoderma product were not effective in enhancing onion bulb and yield characteristics under the given conditions.  相似文献   

14.
Proteaceae are adapted to low-nutrient soils in the various regions where they occur. However, harvesting of flowering stems for the cut-flower industry must eventually cause soil nutrient depletion sufficient to reduce yields. Different N forms, and N and P concentrations were supplied to two Proteaceae cultivars (Leucadendron ‘Safari Sunset’ and Leucospermum ‘Succession’) in a controlled fertigation experiment, and appropriate concentrations for maximum growth with minimum nutrient accumulation or loss were determined. Small additions of N (0.025–0.1 mM) significantly improved growth of both cultivars growing on Strandveld sandy soil. Larger additions of N (up to 2 mM N) resulted in poor growth (both cultivars) and N accumulation in the soil (Safari Sunset). Small additions of P (<10 μM) significantly improved growth of both cultivars and resulted in no accumulation or loss of P in the soil. Larger additions of P (up to 500 μM) resulted in poor growth, P toxicity symptoms and P leaching from the upper soil layers. Best N forms in descending order of both plant visual appearance and vegetative yield were: urea ≥ ammonium nitrate > ammonium sulphate > calcium nitrate. Phosphorus toxicity symptoms were associated with increased concentrations of leaf P, Ca and Fe. Under conditions of maximum growth (10 μM P and 0.1 mM N) Safari Sunset removed 18 ± 0.6 g N, 1.5 ± 0.1 g P, 5.3 ± 0.6 g K and Succession removed 5.5 ± 0.2 g N, 0.3 ± 0.02 g P, 3.1 ± 0.5 g K over 6 months. At maximum growth, plants acquired more N and P amounts than were supplied, but supplying higher N and P concentrations adversely affected growth. Thus, a more complex or slow-release form of N and P than urea and soluble phosphate, respectively, may provide enough N and P to replace losses from the farm soil at the low concentrations required for proteas.  相似文献   

15.
The aim of this research was to determine the influence of various forms, diverse doses, and dates of application of nitrogen fertilizers and foliar nutrition on the concentration of sugars, carotenoids and phenolics compound in carrot. Two field experiments (Experiment I in 2003–2005 and Experiment II in 2004–2005) with carrot ‘Kazan F1’ were conducted in Trzciana (50°06′N; 21°85′E) in Poland. Both experiments were arranged in a split-plot design with four replications. Two sub-blocks were identified in both experiments: sub-block (A) without foliar nutrition and sub-block (B) with plant foliar nutrition. In sub-block (B), plants were sprayed three-times with: 2% (w/v) urea, a 1% (v/v) solution of multi-component ‘Supervit R’ fertilizer, and again with 2% (w/v) urea. Combinations with diversified nitrogen fertilization were distinguished within both sub-blocks. The treatments in Experiment I consisted of: (1) Control, (2) 70 kg N ha−1 as Ca(NO3)2, (3) 70 + 70 kg N ha−1 as Ca(NO3)2, (4) 70 kg N ha−1 as (NH4)2SO4 and (5) 70 + 70 kg N ha−1 as (NH4)2SO4, where 70 kg N ha−1 was used preplant and 70 + 70 kg N ha−1 was applied preplant and as a top dressing, respectively. The treatments in Experiment II consisted of: (1) Control, (2) 35 + 35 kg N ha−1 as ENTEC-26, (3) 70 + 70 kg N ha−1 as ENTEC-26, (4) 105 + 105 kg N ha−1 as ENTEC-26, (5) 35 + 35 kg N ha−1 as NH4NO3, (6) 70 + 70 kg N ha−1 as NH4NO3, (7) 105 + 105 kg N ha−1 as NH4NO3, where 35 + 35, 70 + 70, 105 + 105 kg N ha−1 was applied preplant and as top dressing, respectively. Solid nitrogen fertilizer was added to the soil, as produced: Ca(NO3)2—Yara International ASA (Hydro), (NH4)2SO4—Zak?ady Azotowe w Tarnowie, Poland, NH4NO3—Zak?ady Azotowe w Pu?awach, Poland and ENTEC-26–COMPO GmbH & Co., KG, Germany. In Experiment I, the highest sugar concentrations were found in carrot fertilized with (NH4)2SO4 70, while in Experiment II in the control and after fertilization with ENTEC-26 35 + 35 kg N ha−1. In both experiments N-fertilization affected an increase in phenolic compound concentrations in comparison with the control. Experiment I revealed no significant effect of N-fertilization on carotenoid concentrations in carrot, however in Experiment II the highest concentration of these compounds was characteristic for the control plants and carrot fertilized with ENTEC-26 35 + 35. The foliar nutrition applied in Experiment I caused a decline in sugar concentration and an elevated carotenoid concentration, however it had no influence on the phenolic compound concentrations in carrot. Yet the foliar nutrition in Experiment II led to a decrease in phenolic and carotenoid compound concentrations, but it did not affect sugar concentration in carrot.  相似文献   

16.
Water logging and salinity of the soil alter both the physical and biological environment of plant roots. In two experiments, we investigated the effects of imposed aeration on yield and the physiological response of tomato (Lycopersicon esculentum L.) variety Improved Apollo growing under protected conditions over a range of salinities (the salinity experiment), and under constant field capacity (FC) or drier soil conditions (the moisture experiment). Subsurface irrigation with aerated water (12% air in water) stimulated above-ground growth, and enhanced the reproductive performance through earliness for flowering and fruiting compared with the control. Fruit yield of tomato with aeration in the moisture experiment was increased by 21% compared with the control (4.2 kg versus 3.7 kg per plant), and the effect of aeration on fruit yield was greater in FC than in the drier treatment. Fruit yield was increased by 38% in saline soil due to aeration compared with the non-aerated control. Increasing salinity from 2 to 8.8 dS m−1, and 10 dS m−1 reduced fruit yield by 18% and 62%, respectively, but 4 dS m−1 did not suppress yield. Aeration in both the experiments increased plant water use and water use efficiency (WUE), expressed as weight per unit of applied water. Biomass WUE was greater by 16% and 32% in the moisture and salinity experiments, respectively. The increased yield with aeration was also accompanied by an increased harvest index (HI) defined as the proportion of dry fruit biomass to total dry biomass, greater mean fruit weight, high fruit DM, and increase in leaf chlorophyll content and shoot: root ratio, and a reduced water stress index (computed from the difference between air and leaf temperature). The benefit gained from aerating irrigation water was not only observed under conditions where air-filled porosity may be low (e.g., in poorly structure sodic soils, or at field capacity in clay soils), but also in drier soils.  相似文献   

17.
A romaine-type lettuce (Lactuca sativa L.) cv. Corsica was cultivated during three successive crop seasons (late-spring, late-autumn and late-winter) in the same soil of an experimental greenhouse in S.W. Peloponnese, Greece. Seven long-term fertilization treatments were tested for their effect on plant growth and nitrate concentration in the external lettuce leaves. Treatments included: three different doses of organic fertilization (composted sheep manure) applied at the start of each crop season, three different doses of inorganic N fertilization applied via fertigation during each crop season, and a control treatment in which no fertilizer was applied. A drip irrigation system was used to water all plants. The highest nitrate levels were observed in the medium and maximum inorganic fertilization treatments (572–664 mg kg−1) in all crop seasons. They were significantly higher compared to the respective organic fertilization treatments (253–435 mg kg−1) and all other fertilization treatments (148–435 mg kg−1). Crop season affected lettuce growth more than nitrate accumulation in the lettuce leaves: lettuce biomass production was the smallest and most uniform in the late-autumn season and did not respond to the fertilization treatments tested (ranging from 409 to 439 g plant−1), while in the late-spring season biomass production was the highest and most variable (561–841 g plant−1), it correlated with nitrate concentration in the leaves and in the medium and maximum inorganic fertilizer doses it significantly exceeded production from all other fertilization treatments (827–841 g plant−1). Following the three crop seasons the residual availability of N, P and K was clearly enhanced in the soil receiving the organic compared to the inorganic fertilization. Nitrate concentration in lettuce leaves was far below the upper limits set by the European Commission in all fertilization treatments throughout the three crop seasons, a result attributed mainly to the sufficient level of light intensity and duration throughout the year in Southern Greece.  相似文献   

18.
Urban agriculture, as most agriculture, can potentially contribute to eutrophication via losses to ground and surface water. Few published studies have empirically measured nitrogen and phosphorus losses (including leaching) from urban agriculture, and even fewer have examined losses in real-world settings throughout the year. Here we investigated year-round (May 2020–2021) weekly nitrogen and phosphorus leaching from allotment gardens in Linköping, southern Sweden. We installed eight lysimeters (8 plots) and collected water 0.3 m below the soil surface in four gardens (2 plots per garden), each with their own gardening practices (organic fertilizers, irrigation, and crops). The gardens exhibited large nutrient leaching per area cultivated compared to observed nutrient leachate in rural agriculture in similar climates. There was a large variability among studied plots, where nitrogen leaching reached 39–191 kg ha−1 y−1 and phosphorus 0.9–2.4 kg ha−2 y−1. Importantly, the non-growing season, especially snowmelt, was a key period for leaching. Most of the nitrogen (78–91 %) and phosphorus (45–97 %) leaching occurred from November to April when the soil was bare, suggesting that mineralization of organic matter was important. Three of the gardens received high amounts of organic fertilizers, though no clear relation between inputs and leaching could be discerned. One plot deviated from the pattern, with less than 40 % of the nutrient leaching occurring in the non-growing season. This gardener had a fine net covering the plot to deter insects. This protected from precipitation as the water volume collected was the lowest, with only 26 % collected in the non-growing season, and nitrogen leaching was also the lowest. Our results illustrate that additional monitoring studies should occur year-round and in several gardens to account for high temporal and spatial heterogeneity and avoid under-estimating leaching losses from urban agriculture. Providing guidance on fertilization, irrigation, and soil covering may be a way to minimize leaching.  相似文献   

19.
Fertilizer recommendations for citrus production on heavier textured, calcareous soils increase with the age of the tree up to 168 kg N ha−1 year−1 from a soluble source in one or two applications. Such practices may be inefficient and could cause detrimental effects on fruit quality. A variety of fertilization practices are used in South Texas, and additional evaluation is needed. Rates and sources of nitrogen (N), phosphorus (P), and a commercial program consisting of both a soil component containing organic acids and a foliar component were evaluated on grapefruit production for 6 years. Increasing rate of N application increased leaf nutrient concentration, grapefruit yield, and affected fruit shape as indicated by a decrease in the equatorial:polar diameter (E:P) ratio. Since the response to increasing N application by the E:P ratio was linear while grapefruit yield was quadratic, high N application has a negative effect on fruit shape beyond the level of increasing total yield. Phosphorus application had no effect on any parameter measured, even though soil testing indicated soil P levels were below those at which a P response would be expected. Comparisons between granular 21-0-0 applied broadcast and liquid N-32 injected in a band in the soil at the drip line showed an increase in the number of fruit per tree, but no differences in yield. The ‘Actagro’ program greatly improved available soil P levels and increased the juice brix:acidity ratio, but did not affect grapefruit yield. Phosphorus availability may therefore be a factor in improving grapefruit juice quality. The soil profile within the citrus root zone was found to contain large amounts of inorganic N, but availability of this residual N was limited since yield responses occurred at the N application rates applied in this study. The amount of N contained in the fruit harvested was a small fraction, roughly 5–10%, of the residual amount in the soil. While N uptake in the fruit increased with N fertilizer application, the increase in N taken up relative to the amount applied averaged 42%.  相似文献   

20.
In the warm and wet north Florida climate, growing Italian parsley (Petroselinum crispum [Mill.]) is gaining popularity with small producers as a short duration crop on sandy soil. Application of compost to agricultural land can benefit the low fertile sandy soils in Florida and subsequent crop production, while providing an outlet for recycling municipal solid wastes (MSW) and biosolids. A field study was laid out in a randomized complete block design with four replications to evaluate the effects of compost (75% MSW:25% biosolids) application in comparison to fertilizer, fertilizer + compost (50:50), and control treatments on: (a) parsley fresh weight (FW), (b) soil and plant tissue nutrient concentrations, and (c) soil bulk density and moisture retention in winter and spring seasons. Soil amended with fertilizer or compost + fertilizer doubled parsley FW from 15.02 Mg ha−1 in the non-amended control plot to 30.75 and 32.67 Mg ha−1 in soils that received fertilizer + compost or fertilizer alone, respectively. Significantly higher total soil carbon (C) levels of 2.16% and 1.95% and nitrogen (N) levels of 0.19% and 0.16% were recorded in compost and fertilizer + compost treatments, respectively. Addition of compost reduced soil bulk density significantly to 1.03 Mg m−3 and increased soil moisture retention in simulated drier conditions at 1500 kPa to 0.12 m3 m−3 in plots that received only compost at the end of winter growing season. Overall, addition of compost resulted in improvement of both physical and chemical properties as well as increased parsley yields.  相似文献   

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