| This experiment was performed to study soil ionic interaction and its effect on celery（Apium graveolens L.） growth and elemental uptake, and the effects of different soilamendments on greenhouse soil properties and cucumber （Cucumis sativus L.） yield, based onthe assessment of soil quality and asparagus yield in an area of greenhouse cultivation onChongming Island, China. This study included three parts and results were as follows:1. This study was undertaken to determine the spatial variability of in situ electricalconductivity （ECa）, pH, organic matter, soil salinity and spear yield of asparagus （AsparagusOfficinalis L.） in an area of plastic-greenhouse cultivation on Chongming Island, China,which could help the growers for good management practices. Results showed that soil spatialvariability was weak or moderate in each of greenhouse management areas, but moderate orstronge for all the study area. This indicated that the impacts of human activities ongreenhouse soil spatial variability were prominent, such as fertilization and managementpractices, but natural factors such as the formation of terrestrial were second. In thegreenhouse soil, sodium salt was not prominent （ESP <15）. There was a significantcorrelation between ECa and1:5soil/water EC. Total soil salt content was more than theupperlimitation of plant adaption in95%of total area of greenhouse cultivation. The spatialvariability of asparagus spear yield was weak for different growers. However, differentmanagement practices significantly affected soil salinity and asparagus spear yield ingreenhouse cultivation, and excessive salinity of greenhouse soil could result in decreasedasparagus spear yield.Fertilization, irrigation, crop yield and soil quality were investigated from2007to2009in different cropping systems （greenhouse monoculture, greenhouse rotation and open fieldrotation） in order to study the reason of greenhouse soil degradation. Results showed thatdifferent cropping systems significantly affected soil quality. Although soil organic carbon,mineral nitrogen, available phosphorus and exchangeable potassium content increased ingreenhouse cultivation compared to open field rotation, greenhouse cultivation significantlyincreased soil EC, and NO3-and Cl-contents. Meanwhile, pH values decreased by0.6and0.4 in the greenhouse monoculture and greenhouse rotation, repectively, while did notsignificantly change in open field rotation. In addition, greenhouse soil salinization had adeterious trend with increasing planting year, while EC value did not significantly change inopen field rotation. In asparagus monoculture greenhouse, soil EC even approached10mScm-1, which outclassed soil EC (0.27mS cm-1) in open-field rotation. Investigation indicatedthat high cropping index, excessive fertilizer input and inappropriate irrigation resulted ingreenhouse soil quality degradation due to weak farmer’s skill and local extention services.2. Greenhouse pot experiments were performed to optimize phosphorus （P） fertilizationunder different Calcium （Ca） and magnesium （Mg） levels and to study effects of thesenutrients on celery growth, quality and nutrient uptake. Results showed that P treatmentscould significantly decrease electrical conductivity in the substrate, while substrate ECincreased with increasing the level of Ca and Mg. Meanwhile, there were significantinteractions between P application and the level of Ca and Mg. Celery above-ground freshweight, total dry biomass, leaf area and P concentration in celery leaves significantlyincreased at low P treatments （0-4mM）, whereas at high P treatments (4-16mM) did notsignificant change. The opposite trend was observed for root/shoot ratio, leaf chlorophyll,carotenoids, soluble protein, soluble sugar, ascorbic acid （vitamin C） and nitrogenconcentration in celery leaves. The medium levels of Ca and Mg （8mM Ca and8mM Mg）significantly increased celery above-ground fresh weight, total dry biomass and leaf areacompared to the low （4mM Ca and4mM Mg） and high （16mM Ca and16mM Mg） level ofCa and Mg at the4-16mM P treatments. This study suggested that4-8mM P applicationunder medium levels of Ca and Mg was appropriate to satisfy the nutritional requirements forimprovement of horticultural characteristics. Meanwhile, interactions between availableelements in the mixed organic substrate of peat and sand （95:5, w/w） as affected by potassium（K） under different calcium （Ca） and magnesium （Mg） levels, and effect of these nutrients oncelery growth, quality and nutrient uptake were studied. Results showed that EC values insubstrate significantly increased with increasing K application, and the level of Ca and Mg insupplied nutrient solution, respectively. K application could significantly decreased availableCa and Mg contents in substrate. Increased level of Ca and Mg significantly increased Mgcontent in substrate and decreased K, while did not significantly affect Ca. Mn content in substrate significantly increased with increasing level of Ca and Mg. available K content insubstrate had significant relation with K content in root, stalk and leaf of celery, and Ca andMg in substrate were significantly related with in stalk and leaf. K application significantlyincreased celery yield, while high level of Ca and Mg inhibited celery growth. Soluble proteinand vitamin C in stalk of celery had significant relation with EC in substrate, respectively. Caand Mn contents in leaves of celery were significantly related with yield, respectively. Kcontent in root of celery was significantly negatively related with Na and Mg in root, whilenot related with Ca. K content in stalk and leaves of celery were significantly negativelyrelated with Na and Ca, respectively, while not related with Mg.3. The use of organic materials （peat moss, bran coat, asparagus residues, turf clippingand soybean residues）, adsorption materials （weathered coal and activated carbon）, chelators（wood vinegar dissolved chitosan and acetic acide dissolved chitosan）, microbial fertilizers（trichoderma,“Lian chawang” and “Hu genbao”） and mineral fertilizers （FeSO4, KH2PO4andKCl） as soil amendments for greenhouse cucumber production was studied. Different organicmaterials have different properties, especially elemental contents. The content of carbon inbran coat was highest among all the organic materials, the potassium content in asparagusresidue highest, the contents of phosphorus and potassium in turf clipping highest, andnitrogen content in soybean residues highest. However, the contents of copper in asparagusresidue and turf clipping were more than the standard when as soil amendments. Organicmaterials significantly increased soil organic carbon and available potassium content. Soilmineral nitrogen was significantly increased by soybean residues and asparagus residuessignificantly increased soil available phosphorus content. Organic materials significantlyincreased soil catalase and invertase activities except for peat moss. Soil amylase activity wassignificantly increased by mildewy bran coat and soybean residues, while mildewy bran coatand asparagus residues significantly decreased soil urease activities. Organic materialssignificantly increased cucumber yield and decreased nitrate contents. Asparagus residuetreatment could significantly increased potassium and magnesium contents in cucumber fruit.Active carbon and weathered coal could increase the buffering capacity of greenhouse soil,and improve cucumber growth, yield and quality. The wood vinegar solution of chitosan andthe acetic acid solution of chitosan treatments have significantly promoting effects on cucumber compared to the control, but no significant difference was observed between them,indicating wood vinegar could substitute acetic acid in agricultural production. In addition,trichoderma and mineral fertilizers could increased cucumber yield and decreased the NO3-content in cucumber fruit compared to the control. This study suggested that the combinationof different types of amendments was applied to the greenhouse soil, which could achievebetter results. |
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