Changes in Tomato Fruit Quality and Antioxidant Enzyme Activities under Deficit Irrigation and Fertilizer Application in a Solar Greenhouse in Northwest China

The interaction between water availability in the soil and fertilizer application rates often strongly affects crop growth. In the current study, the quality of fresh fruit and antioxidant enzymes of tomato crops (Lycopersicon esculentum Mill) were investigated under different irrigation (low water content [W_l]: 50 ~ 60% field moisture capacity (FMC); moderate [W_m]: 70 ~ 80% FMC; and high [W_h]: 90 ~ 100% FMC) and fertilizer conditions (deficit fertilizer [F_l]: 195 kg ha^?1 nitrogen (N) + 47 kg ha^?1 phosphorus pentoxide (P₂O₅) and moderate [F_m]: 278 kg ha^?1 N + 67 kg ha^?1 P₂O₅) in a solar greenhouse. The results showed that the quality of fresh fruits and the antioxidant enzyme activities in the leaves and fruits were related to the water content in the soil. Deficit irrigation improved the fruit quality and 50 ~ 60% FMC combined with fertilizer application rates of 195 kg ha^?1 N + 47 kg ha^?1 P₂O₅ is recommended for tomato crop cultivation under greenhouse conditions.     

Effect of Raw and NH4+-enriched Zeolite on Nitrogen Uptake by Wheat and Nitrogen Leaching in Soils with Different Textures

Leaching of nutrients in soil can change the surface and groundwater quality. The present study aimed at investigating the effects of raw and ammonium (NH₄⁺)-enriched zeolite on nitrogen leaching and wheat yields in sandy loam and clay loam soils. The treatments were one level of nitrogen; Z₀: (100 kg (N) ha^?1) as urea, two levels of raw zeolite; Z₁:(0.5 g kg^?1 + 100 kg ha^?1) and Z_2: (1 g kg^?1 + 100 kg ha^?1), and two levels of NH₄⁺-enriched zeolite; Z₃: (0.5 g kg^?1 + 80 kg ha^?1) and Z₄: (1 g kg^?1 + 60 kg ha^?1). Wheat grains were sown in pots and, after each irrigation event, the leachates were collected and their nitrate (NO₃^?) and NH₄⁺ contents were determined. The grain yield and the total N in plants were measured after four months of wheat growth. The results indicated that the amounts of NH₄⁺ and NO₃^? leached from the sandy loam soil were more than those from the clay loam soil in all irrigation events. The maximum and minimum concentrations of nitrogen in the drainage water for both soils were observed at control and NH₄⁺-zeolite treatments, respectively. Total N in the plants grown in the sandy loam was higher compared to plants grown in clay loam soil. Also, nitrogen uptake by plants in control and NH₄⁺-zeolite was higher than that of raw-zeolite treatments. The decrease in the amount of N leaching in the presence of NH₄⁺-zeolite caused more N availability for plants and increased the efficiency of nitrogen fertilizers and the plants yield.     

Prevention of Iron‐Deficiency Induced Chlorosis in Kiwifruit (Actinidia deliciosa) Through Soil Application of Synthetic Vivianite in a Calcareous Soil

Abstract

In this study we have tested the hypothesis that lime‐induced Fe deficiency chlorosis of kiwifruit may be prevented by the application of a synthetic iron(II)‐phosphate analogous to the mineral vivianite [(Fe₃(PO₄)₂·8H₂O)]. Two experiments, under greenhouse and field conditions, were performed. In the greenhouse, 1‐year old micropropagated plants (Actinidia deliciosa, cv. Hayward), grown in 3‐L pots on a calcareous soil, were treated in early autumn with soil‐applied: (1) synthetic vivianite (1.35 g plant^?1) and (2) Fe‐EDDHA (24 mg Fe plant^?1). The synthetic vivianite suspension, prepared by dissolving ferrous sulfate and mono‐ammonium phosphate, was injected into the soil as a sole application whereas the Fe‐EDDHA solution was applied four times at weekly intervals. The field experiment was conducted in a mature drip‐irrigated kiwifruit orchard located on a calcareous soil in the Eastern Po Valley (Italy). Treatments were performed in early autumn by injecting synthetic vivianite (1.8 kg tree^?1) and Fe‐EDDHA (600 mg Fe tree^?1) into four holes in the soil around each tree, at a depth of 25–30 cm. The Fe‐chelate application was repeated at the same rate in the following spring. Untreated (control) plants were used in both experiments. Autumn‐applied Fe fertilisers significantly prevented development of Fe chlorosis under greenhouse conditions whereas in the field only vivianite was effective. In conclusion, these 1‐year results show that vivianite represents an effective alternative to soil‐applied Fe chelates for preventing Fe chlorosis in kiwifruit orchards.     

Effects of Different Irrigation Levels and Arbuscular Mycorrhizal Fungi (AMF), Photosynthesis Activator,Traditional Fertilizer on Yield and Growth Parameters of Dry Bean (Phaseolus Vulgaris L.) in Arid Climatic Conditions

A field experiment has been conducted to determine the effects of different irrigation water and AMF (Arbuscular Mycorrhizal Fungi) biofertilizer, photosynthesis activator and traditional fertilizer dry bean (Phaseolus vulgaris L.) on yield and growth parameters in Nevsehir Province of Turkey in 2015. The experiment has been carried out using three replications in a split plot design with three different irrigation types as main plots and AMF biofertilizer (ERS), photosynthesis activator (Multigreen-Mg), traditional fertilization (TF-Control), ERS + Mg, ERS + TF and TF + Mg applied as subplots. The number of pods per plant, the length of pods, the number of grains per pod, the weight of grains per plant, the yield of grains, 1000 seed weight, the number of grains per plant, protein yield, arbuscular mycorrhizal fungi rate have been evaluated as yield and growth criteria in the study. In the experiment, as well as the treatment x irrigation interaction, the plant height, pod number per plant, pod lenght, grain number per pod, grain weight per plant, grain yield, 1000 seed weight, grain number per plant, protein rate/grain, protein yield, root weight and AMF colonization parameters, were the other studied properties that were found to be significant. The results obtained were 877.6 mm for I₁₀₀ irrigation treatment, 512.2 mm for I₅₀ irrigation treatment and 40.19 mm water for I₃₀ irrigation treatment. Regarding the growth parameters of dry bean, the highest PH was in ERS + Mg (67.66 cm), the lowest PH was in ERS (54.33 cm); In I₅₀, the highest Plant Height (PH) was in ERS + Mg (65.66 cm), the lowest PH was in TF-Control (53.00 cm); and in I₃₀, the highest PH was in TF-Control (50.66 cm), and the lowest PH was again in ERS + Mg (44.33 cm). For protein yield (PY) value, ERS + Mg, ERS + TF, TF + Mg have been placed in the same group, in I₁₀₀ and I₅₀ irrigation treatment. The highest value was ERS + TF (34.90 kg da^?1) in I₁₀₀, The lowest value was TF-control (19.90 kg da^?1) in I₃₀ irrigation treatment. In terms of mycorrhiza colonization ratio, ERS has been ranked first in all irrigation treatments, while the highest mycorrhiza colonization has been observed in I₃₀ irrigation treatment (26.30%). ERS was followed by ERS + Mg (23.33%). As expected, the lowest mycorrhiza colonization ratio in all irrigation treatments have been observed in TF-control treatment, while the highest mycorrhiza colonization ratio has been respectively observed in I₃₀ and I₅₀ irrigation topics. The highest root weight (RW) in I₁₀₀ irrigation treatment was observed in ERS (15.06 g plant^?1) and it was observed in ERS (19.05 g plant^?1; 26.30 g plant^?1) in I₅₀ and I₃₀ irrigation treatments. The lowest RW in all irrigation treatments has been observed in TF + Mg (4.43 g plant^?1, 6.40 g plant^?1, 10.26 g plant^?1), respectively.     

Petiole N,P, K Concentrations and Yield of the Potato Cultivar Molli from Certified Organic Amendments and Fertilizer Formulations

This study evaluated the petiole uptake of nitrogen, phosphorus, potassium, and sulfur (N, P, K, and S) by the potato from two seed meals, mint compost, and five commercially available organic fertilizers under an irrigated certified organic production system. Available soil nitrate (NO₃-N) and ammonium (NH₄-N) from each amendment averaged 115 kg N ha^?1 at application and 25 kg N ha^?1 30 d after planting through harvest, with minor differences between fertilizers. Petiole N declined from an average of 25,000 mg N kg^?1, 4 wk after emergence to 3,000 mg N kg^?1 prior to harvest. Petiole P and K concentrations were maintained above 4,000 mg P kg^?1, 10,000 mg K kg^?1, and 2,000 mg S kg^?1 tissue, respectively, throughout the growing season in all treatments. Tuber yields were not different between fertilized treatments averaging 53 Mg ha^?1. This study provides organic potato growers baseline information on the performance of a diverse array of organic fertilizers and amendments.     

Potassium fertilization and soil diagnostic criteria for forage corn (Zea mays L.) production contributing to lower potassium input in regional fertilizer recommendation

Abstract

Effective soil diagnostic criteria for exchangeable potassium (Ex-K) combined with inorganic potassium (K) application rates were developed to lower K input in forage corn (Zea mays L.) production using experimental fields with different application rates and histories of cattle manure compost. Two corn varieties, ‘Cecilia’ as a low K uptake variety and ‘Yumechikara’ as a high K uptake variety, were selected from among 20 varieties and tested to make diagnostic criteria for K fertilization applicable to varieties with different K uptakes. The K uptakes increased from 96 to 303 kg K ha^?1 for ‘Cecilia’ and from 123 to 411 kg K ha^?1 for ‘Yumechikara’ with increasing Ex-K content on a dry soil basis from 0.11 to 0.92 g kg^?1 with no inorganic K fertilizer application. The K uptake by corn for achieving the target dry matter yield of 18 Mg ha^?1 was estimated to be approximately 200 kg K ha^?1 in common between the two varieties. Yields of both varieties achieved the target yield at an Ex-K content of approximately 0.30 g kg^?1 with no K fertilization, although ‘Yumechikara’ reached the target yield at a lower Ex-K content. At the low Ex-K content of 0.1 g kg^?1, inorganic K fertilizer application at 83 kg K ha^?1 was needed to gain the target yield, and apparent K recovery rate for K fertilizer was calculated to be 70% for both varieties. The K uptakes for gaining the target yield by the K fertilization were lower than that by soil K supply. Based on these results, diagnostic criteria of Ex-K and inorganic K application rates were set up as follows: at an Ex-K content of < 0.15 g kg^?1, inorganic K fertilizer is applied at 83 kg K ha^?1 (100 kg ha^?1 as potassium oxide (K₂O) equivalent); at an Ex-K content of 0.15–0.30 g kg^?1, the application rate is reduced to 33 kg K ha^?1 (40 kg K₂O ha^?1); at an Ex-K content of ≥ 0.30 g kg^?1, inorganic K fertilizer is not applied because of sufficient K in the soil. Additionally, we propose that cattle manure compost be used to supplement soil K fertility.     

Effects of Biozyme (Ascophyllum nodosum) Biostimulant on Growth and Development of Soybean [Glycine Max (L.) Merill]

Field experiment was conducted to investigate the effects of Biozyme^TM on soybean. Application of Biozyme granule and crop-plus spray with half of recommended nitrogen, phosphorus, and potassium (NPK) showed significant effects on all the growth and yield parameters of soybean. The greatest value for the number of trifoliate leaves (29.95 leaves plant^?1), leaf area (1818.21 cm2 plant^?1), leaf area index (5.946), total chlorophyll content (1.995 mg g^?1 leaf fresh mass), number of nodules (35.086 plants^?1), fresh and dry weight of nodules (0.664 and 0.1592 g plants^?1), dry weight of root (8.564 g plants^?1), pods plant^?1 (69.0), seeds pods^?1 (3.25), straw yield (3.122 t ha^?1), biological yield (6.349 t ha^?1), and grain yield (3.277 t ha^?1) was observed with Biozyme crop-plus spray at 500 mL ha^?1 plus half of recommended NPK and were significantly greater than control values. Biozyme crop-plus spray at 500 mL ha^?1 plus half of recommended NPK performed better compared to other treatments.     

Evaluation of methods of nutrient and water management on tea performance and nutrient loss in the Danjiangkou Reservoir area,China

The long-term control of fertilizer pollution in the Danjiangkou Reservoir is an important task, and promoting good fertilizer pollution control methods is necessary to conserve water quality. A 3-year experiment was conducted to evaluate the fertilizer losses, economic benefits, and feasibility of different nutrient and water management methods in the area. The experiment included the following treatments: (1) local recommended fertilizer dose (450, 144, and 189 kg ha^?1 y^?1 of N, P₂O₅, and K₂O) under rain-fed conditions (CK); (2) chicken manure at 7500 kg ha^–1 without drip irrigation (OF); (3) same dosage of treatment OF but with drip irrigation (OFD); and (4) drip fertigation with 30% of the fertilization dose of CK (DF). The results showed that organic fertilizer and drip fertigation treatments reduced total N (TN) and total P (TP) losses compared to CK due to considerably less amounts of N and P nutrient inputs. Total N runoff losses, and TN and TP concentrations in leaching water did not differ significantly among treatments OF, OFD, and DF. Net income among the CK, OF, and OFD treatments did not differ significantly. Treatment DF resulted in 19.5% and 13.8% more net income than CK and OFD, respectively. Such results provided guidance for promotion to maximize benefits and minimize environmental impacts.     

EFFECT OF THE APPLICATION OF MONOSILICIC ACID ON THE PRODUCTION AND QUALITY OF TRIPLOID WATERMELON

Experiments were conducted in two consecutive years in a multilayered plastic-covered greenhouse, of the “raspa and amagado” (covered skeleton structure) types in the fields of Almeria (south-eastern Spain), to evaluate the production and quality of a triploid watermelon crop (Citrullus lanatus Thunb) cv. ‘Queen of Hearts’ grafted onto the (Cucurbita maxima x Cucurbita moschata) squash hybrid cv. ‘Strongtosa’. A 2.5% solution of the monosilicic acid [Si(OH)₄] product was applied to this crop in the drip irrigation system at a dose of 260 mL·ha^?1 in both experiments. Results showed that the product did not influence productive parameters in terms of kg of product·m^?2, kg plant^?1, or number of fruits plant^?1. Nevertheless the monosilicic acid [Si(OH)₄] product appeared to have a positive effect on some quality aspects of the fruit with an approximate 10% increase in pulp consistency and rind width.     

Response of Lima Bean to Inorganic Nitrogen and Broiler Manure Sources and Rates

Abstract

Applying animal manure to crops is a good disposal practice that also recycles nutrients. A 2‐year study was conducted involving lima bean (Phaseolus lunatus L.) and two N sources, ammonium nitrate (AN, 340 g N kg^?1), and broiler chicken manure (BM, 10 g N kg^?1). The sources were tested at five N rates (0, 67, 135, 202, and 269 kg N ha^?1) in a split‐plot design with N source as the main plot and N rate as the subplot. Treatments were replicated three times in 2000 and four times in 2001. Leaf tissue (early flowering stage) was analyzed for nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sodium (Na), iron (Fe), copper (Cu), manganese (Mn) and zinc (Zn). Although most nutrients were within or above the sufficiency range, K and Cu limited crop production for all treatments. There was no difference between N sources for fresh pod yields. The highest fresh pod yield occurred at 213 kg N ha^?1, but the critical point was obtained with 100 kg N ha^?1, a rate agreeing with current University of Florida recommendations.     

Macro-Nutrient Concentration and Content of Irrigated Soybean Grown in the Early Production System of the Midsouth

Macro-nutrients in soybean (Glycine max L. Merr.) have not been extensively researched recently. Concentrations and contents of nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur (N, P, K, Ca, Mg, and S) were determined for three irrigated cultivars grown using the early soybean production system (ESPS) on two soils (a sandy loam and a clay) in the Mississippi Delta during 2011 and 2012. Data were collected at growth stages V3, R2, R4, R6, and R8. No change in macro-nutrients due to soil type or years occurred and modern cultivars were similar to data collected >50 years ago. Mean seed yield of 3328 kg ha^?1 removed 194.7 kg N ha^?1, 16.5 kg P ha^?1, 86.0 kg K ha^?1, 17.5 kg Ca ha^?1, 9.0 kg Mg ha^?1, and 10.4 kg S ha^?1. Increased yields over the decades are likely due to changed plant architecture and/or pests resistance, improved cultural practices, chemical weed control, and increased levels of atmospheric carbon dioxide (CO₂). Yield improvements by genetically manipulating nutrient uptake appear to be unlikely.     

Diversity of humus stocks in the arable soils of the Late Pleistocene ground morains in Mecklenburg,West Pomerania,Germany

Abstract

Local humus stocks (= contents of soil organic matter, SOM in kg · m^?2) of arable soils were investigated in several regions of the seemingly uniform ground moraine-landscape. Depending on relief position, quantifiable effects of humus removal or enrichment are evident, caused by denudation or colluviation. The depth (thickness) of the investigated humus-bearing topsoil horizons varies between 15 and 150 cm overall and amounts on average to 67 cm. Extreme values of SOM (resp. C_org) stocks are 2.73 (1.58) and 137.41 (79.70) kg · m^?2. The average values of all found SOM (resp. C_org) stocks in the investigated arable soils amount to 10.78 (6.25) kg · m^?2. Humus stocks are not only of importance for the agricultural yield potential but also because of their function as a sink for, or a source of, atmospheric CO₂, which is of special current interest due to its influence on menacing climate change. The total carbon content of the corresponding column of atmosphere, 1.60 kg · m^?2, amounts to only one quarter of the average in our arable soils.     

基质栽培甜瓜矿质营养吸收规律的研究

以温室基质栽培的网纹甜瓜'甜甜1号'为试材,探讨了植株的干物质积累和矿质元素的吸收规律。结果表明,温室内基质栽培网纹甜瓜的生育期为100天,采收时植株总生物量为136g时,单株矿质元素的需求总量为11 09g。营养生长期和结果中期是植株干物质积累的两个重要时期(营养生长期1.27gplant-1d-1、结果中期2.19gplant-1d-1),应增施肥料,以满足植株快速生长的需要。甜瓜对矿质元素N、P、K、Ca、Mg需求的比例,营养生长期为41∶4∶32∶19∶4,结果中期为28∶5∶37∶25∶6。甜瓜的P需求量在结果前期最大(15 55mgplant-1d-1),N、K、Ca、Mg的需求量在结果中期最大,N为52.58mgplantd、K为82.33mgplant-1d-1、Ca为54.59mgplant-1d-1、Mg为12.42mgplant-1d-1。     

Effects of Residual Mulch Film on the Growth and Fruit Quality of Tomato (<Emphasis Type="Italic">Lycopersicon esculentum</Emphasis> Mill.)

The quantities of residual mulch film in the soil will further increase with the wide application of agricultural plastic mulch film, and the pollution of residual mulch film, which is a continuous pollutant and the one that is difficult to degrade, is a major limiting factor for the sustainable development of agriculture in China. Residual mulch film in the soil inevitably affects soil hydrodynamic parameters, destroys the homogeneity of the soil texture, seriously impedes the movement of soil water and solutes, and thus greatly influences crop growth and fruit quality. To unravel the effects of residual mulch film on tomato growth and fruit quality, pot experiments in the greenhouse were carried out in 2015 and 2016 in Northwest China. Six levels of residual mulch film were applied: 0 kg ha^?1 (CK), 80 kg ha^?1 (T1), 160 kg ha^?1 (T2), 320 kg ha^?1 (T3), 640 kg ha^?1 (T4), and 1280 kg ha^?1 (T5). Plant height, stem diameter, dry biomass, yield, root length, root surface area, fruit shape index (FSI), soluble sugar content (SSC), organic acid (OA), vitamin C (VC), lycopene, and nitrate content (NC) were measured. Plant height, stem diameter, dry biomass, and yield of tomato had a downward trend as the residual mulch film amount increased. Root length and root surface area were significantly decreased with an increasing amount of residual mulch film, but root volume and root diameter showed an inconspicuous decrease. When the amount of residual mulch film was more than 80 kg ha^?1, growth indexes, dry biomass, and yield of tomato showed a sharp decline. FSI, OA, and lycopene decreased as the residual mulch film amount increased, whereas SSC, VC, and NC showed an increase trend. With the increase in residual mulch film amount, the F and membership function values (X _μ ) all showed a declining trend in comparison to the CK. Therefore, residual mulch film can aggravate the negative effects on the comprehensive fruit quality of tomato.     

Nitrogen,phosphorus, and potassium effects on the physiology and biomass yield of baby spinach (Spinacia oleracea L.)

Baby spinach is a relatively new crop of commercial significance in South Africa with considerable health attributes. Three parallel trials to investigate its response to nitrogen (N), phosphorus (P), and potassium (K) were conducted. N and P (0, 45, 75, 105, and 120 kg·ha^?1) and K (0, 63, 85, 127, and 148 kg·ha^?1) treatments were applied to baby spinach in a randomized block design with four replications. After the parallel trial, NPK combination trial was also done. The biomass yield, chlorophyll content, and leaf area index increased significantly with increase in N and P rates; K had no effect on the yield, chlorophyll content, stomatal conductance, and leaf area index. Yield and chlorophyll content peaked at 75 kg·ha^?1 of N/P but growth was best optimized at the NPK combination of 45:45:60 kg·ha^?1.     

Nitrate Leaching in Pepper Cultivation with Organic Manure and Supplementary Additions of Mineral Fertilizer

Abstract

Nitrate leaching frequently is attributed to the excessive application of mineral nitrogen fertilizers and also to the organic matter incorporated in the soil. A lysimeter experiment was conducted in a greenhouse to evaluate nitrate leaching and pepper productivity in an organically fertilized substrate (prepared by application of 4 kg · m^?2 horse manure and subsequent solarization) to which three different doses of mineral fertilizers were added at 0 (T1), 157 (T2), and 313 (T3) kg N · ha^?1. The results confirmed the high contribution of organic matter to nitrate leaching, although nitrate losses in T2 and T3 were around 33% and 100% greater than in T1. Furthermore the application of mineral fertilizers (T2 and T3) combined with organic manure led to a decrease in pepper fruit productivity. The use of porous ceramic water samplers for measuring fertilizer leaching is questioned. The results also point to the need for a revaluation of irrigation and N fertilization procedures when organic manure is used in order to improve pepper yield and reduce the contamination of ground water by nitrates.     

Response of Chickpea Cultivars to Application of Boron in Boron‐Deficient Calcareous Soils

Abstract

This study was conducted to investigate the effects of four boron (B) doses (control, 0 kg B ha^?1; B₁, 1 kg B ha^?1; B₂, 3 kg B ha^?1; and B₃, 6 kg B ha^?1) in soils deficient in available B (0.19 mg B kg^?1) and lime (CaCO₃) content (20.7%) on yield and some yield components of five chickpea (Cicer arietinum L.) genotypes, namely Akçin‐91, Population, Gökçe, ?zmir‐92, and Menemen‐92 in central Anatolian Turkey in the 2002 and 2003 growing seasons. Plant height, pods per plant, grain yield, protein content, protein yield, thousand seed weight, and leaf B concentration were measured. Grain yields in all genotypes (except for Gökçe) were significantly increased by 1 kg ha^?1 B application. Application of 1 kg ha^?1 B increased the yield by an average of 5%. Genotypes studied showed significant variations with respect to their responses to additional B. Akçin‐91 gave the highest grain yield (1704.8 kg ha^?1) at 3 kg B ha^?1, whereas Population, ?zmir‐92, and Menemen‐92 yielded best (1468.2 kg ha^?1, 1483.0 kg ha^?1, and 1484.7 kg ha^?1, respectively) at 1 kg B ha^?1. Interestingly, Gökçe reached to the highest level of grain yield (1827.1 kg ha^?1) at the control. Gökçe was a B deficiency B tolerance genotype. The other genotypes appeared to have high sensitivity to B deficiency. This study showed that B deficiency could result in significant yield losses in chickpea under the experimental conditions tested. Thus, B contents of soils for the cultivation of chickpea should be analyzed in advance to avoid yield losses.     

施磷对麦/玉/豆套作体系土壤磷素变化的影响

小麦/玉米/大豆带状套作是四川省丘陵低山区主要旱地作物生产体系,了解该体系磷养分变化对优化磷肥管理和促进可持续生产有重要意义。本研究通过连续3年(2011—2013年)田间定位试验,设置P0、P1、P2、P3和P4共5个磷(P2O5)水平(玉米带分别为0 kg·hm-2、37.5 kg·hm-2、75 kg·hm-2、112.5 kg·hm-2、150 kg·hm-2,小麦-大豆带分别为0 kg·hm-2、45 kg·hm-2、90 kg·hm-2、135 kg·hm-2、180 kg·hm-2),探讨该体系中土壤全磷、速效磷、水溶性磷的变化规律和速效磷的年际变化。结果表明:在麦/玉/豆套作体系中施磷165 kg(P2O5)·hm-2(玉米带75 kg·hm-2,小麦-大豆带90 kg·hm-2),可以满足体系作物对磷的需求,基本达到磷的表观平衡,维持土壤速效磷含量在20 mg·kg-1左右。3年后5个磷水平下体系耕层土壤(0~20 cm)全磷变化量分别为-0.024 g·kg-1·a-1、-0.016 g·kg-1·a-1、0.016 g·kg-1·a-1、0.11 g·kg-1·a-1、0.15 g·kg-1·a-1,速效磷变化量依次为-1.2 mg·kg-1·a-1、-0.9 mg·kg-1·a-1、0.2 mg·kg-1·a-1、2.0 mg·kg-1·a-1和2.7 mg·kg-1·a-1。通过线性平台函数的模拟,该体系中玉米、小麦、大豆产量的土壤速效磷临界值分别为16.5 mg·kg-1、12.6 mg·kg-1和8.8 mg·kg-1。当土壤全磷含量低于0.55 g·kg-1时,土壤全磷每增加0.1 g·kg-1,土壤速效磷增加1.70 mg·kg-1;当土壤全磷大于0.55 g·kg-1,全磷每增加0.1 g·kg-1,土壤速效磷增加6.49 mg·kg-1。当土壤速效磷含量在40 mg·kg-1以下时,速效磷每增加1 mg·kg-1,水溶性磷增加0.017 mg·kg-1。综上,在麦/玉/豆体系磷肥管理中应该维持土壤全磷含量低于0.55 g·kg-1,同时速效磷含量在20 mg·kg-1左右,这样既可以保证作物产量和系统生产力又不会产生较大的环境威胁。     

Solid-Solution Metal Partitioning for the Upper Mero River Basin (NW Spain)

This study determines the seasonal variability of metal partition coefficients [aluminium (Al), iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn)] and analyses the importance of suspended sediments (SS), dissolved organic carbon (DOC) concentrations, pH, and discharge (Q) on the seasonal variability of metal partition coefficients (K_Ds) in the headwaters of the Mero River catchment, which drains an agroforestry area in northwestern Spain. Metal partition coefficients were used as an approach to relate dissolved and particulate fractions. Water samples were collected over 3 years (2005–2008) at the catchment outlet. The mean metal dissolved concentrations were: Fe (43.5 μg L^?1) > Al (23.3 μg L^?1) > Zn (1.8 μg L^?1) > Mn (1.2 μg L^?1) > Cu (0.3 μg L^?1). Partition coefficients followed the order Mn > Al > Fe > Zn > Cu, and their values exhibited low variability. Al, Cu, and Zn partition coefficients presented the greatest values in summer, except during 2007–2008, when the greatest K_Ds value was observed in autumn, whereas the K_Ds of Fe showed the greatest values in winter. The K_D of Mn has no seasonality. For Al, Cu, and Zn, the seasonal SS concentrations were closely related to Kd. For Fe, Kd was more closely related to DOC concentration than to SS concentration.     

Effect of two whole-crop rice (Oryza sativa L.) cultivars on methane emission and Cu and Zn uptake in a paddy field fertilized with biogas slurry

A field experiment was carried out to evaluate the effect of two whole-crop rice (Oryza sativa L.) cultivars, TULT and Takanari, on methane (CH₄) emission in a paddy field fertilized with biogas slurry (BS) at rates of 0 (NF), 100 (BS100) and 300 (BS300) kg nitrogen (N) ha^?1, in comparison with chemical fertilizer CF100 (100 kg N ha^?1). Takanari produced significantly higher biomass (P < 0.001) than TULT and showed significantly (P < 0.01) lower CH₄ emission than TULT. BS applications caused higher CH₄ emission (52 ± 27 and 80 ± 19 g m^?2 in BS100 and BS300, respectively) than did CF100 (42 ± 18 g m^?2) and NF (28 ± 10 g m^?2) in TULT. In contrast, there was no significant difference in CH₄ emission in Takanari among the treatments (26 ± 2, 26 ± 2, 32 ± 4, 29 ± 8 g m^?2 in NF, CF100, BS100 and BS300, respectively). Methane oxidizing bacteria (MOB) showed significantly (P < 0.05) higher populations in Takanari than in TULT at harvest, which might be due to the higher root biomass (10.3 ± 2.2 g hill^?1) in Takanari than in TULT (8.9 ± 1.8 g hill^?1). MOB was significantly correlated with tiller number (R² = 0.176*) and plant biomass (R² = 0.242*). BS application showed higher copper (Cu) uptake in Takanari while it was not high in TULT. In contrast, it showed no difference in zinc (Zn) uptake in both varieties. Uptake of Cu was not different between the two varieties, while uptake of Zn in the grain was higher in TULT than in Takanari. The present study suggests that CH₄ emission deriving from BS application in paddy field can be mitigated by selecting an appropriate cultivar, like Takanari. However, care should be taken for heavy metal uptake in selecting cultivars.