Forms Transformation Of Cadmium In The Manure In Calcareous Soils And Effect On The Yield And Quality Of Chinese Cabbage

Organic fertilizer is essential to agricultural production, plays an important role onincreasing crop yield and quality, improving quality and soil fertility of cultivated land. Inrecent years, with the development of breeding industry and expansion of breeding scale, inorder to combat animal diseases and improve feed utilization some heavy metals are added tofeedstuff, so manure carried of heavy metal that are not absorbed by the animal. If long termapplication organic fertilizer which carried heavy metals to agricultural land, the heavy metalswould accumulate in the soil, lead to reduced quality and safety of agricultural products,endangering human health. Cadmium is one of the strongest toxic to the human bodyelements of heavy metals, study on the transformation and accumulation of cadmium oforganic fertilizer in soil and the effect on the quality of plants can provide reasonableapplication of organic fertilizers in agricultural production with reference.Chinese cabbage was used experimental material in this study, pots simulationexperiments were carried out to study on organic fertilizer in the transformation anddistribution of cadmium in soil and its influence on quality of Chinese cabbage andantioxidant enzymes activities. Explored for three consecutive quarters in the course ofapplication of organic fertilizer in soil cadmium accumulation rates, different forms ofcadmium, cadmium content in Chinese cabbage, cabbage quality indicators, security andantioxidase activity with cadmium levels and variation of amount of fertilizer applied, mainresults were as follow:(1) Application of added exogenous cadmium in organic fertilizer, residue andaccumulation of cadmium in soil were significantly elevated and exceeded maximum size1.0mg/kg of agricultural environmental quality standards (pH>6.5) after fertilization for threeconsecutive quarters, and pure organic fertilizers were less than the maximum size, pigmanure reached440.18μg/kg in rhizosphere. After applying organic fertilizer of addedexogenous cadmium, cadmium in soils mainly was available, pig manure in rhizosphere soilwas98.63%of total, carbonate bound percent rised with the increase of number of plantingseason. After using pure organic fertilizers, mainly existed as residual fraction, average about54.25%in rhizosphere.but after continuous application of three quarters of available cadmiumcontent in the soil there was an upward trend.(2) After three consecutive quarters applying organic fertilizer of added exogenouscadmium, exchangeable form and Fe-Mn oxide bound content in non-rhizosphere soil wasgreater than in the rhizosphere, carbonate bound fraction was reverse, and organic matterbound content were closed in rhizosphere and non-rhizosphere. Total amount of cadmium inedible parts of Chinese cabbage was larger than root and It was significant correlationbetween cadmium absorption in cabbage and exchangeable form、carbonate bound fraction、Fe-Mn oxide bound fraction、organic matter bound, cadmium absorption in Chinese cabbagewas increased with add levels or elevated levels of fertilization.(3) Application of different organic fertilizers can significantly increase the yield ofChinese cabbage, Third quarter was increased an average of2.64times.But sugar and reduced Vc content were reduced of Chinese cabbage, the nitrate and nitrite contents were increased inleaves, edible part of nitrate and nitrite in Chinese cabbage the highest reached910.92mg/kgand6.33mg/kg respectively, parts nitrites was exceeded the maximum4mg/kg of safety levelin the third quarter, partial quality of Chinese cabbage was reduced. Apply fertilizer of addedexogenous cadmium leaded to cadmium content in edible parts of Chinese cabbage and rootsrise, cadmium content in edible parts of Chinese cabbage was160.03~529.69μg/kg and closedto or exceeded the national standard for food safety level of pollutants (0.2mg/kg) in firstquarter application organic fertilizer of added exogenous cadmium, while the effect of pureorganic fertilizer can reduce cadmium content in edible parts of Chinese cabbage and roots.(4) Application of organic fertilizers can increase the soluble protein content of Chinesecabbage, resilience to adversity of environmental stress was increased. Superoxide dismutase(SOD) sensitivity was weaker to low concentrations of cadmium in the soil, but the effectionwas not obvious by added0.3~0.9mg/kg of cadmium, SOD scavenging reactive oxygenspecies of the feature was activated. After fertilization the third consecutive quarter ofperoxidase (POD) and catalase (CAT) with fertilizer were increased after reduced, planttolerance to environmental stresses increased, but excessive fertilization reduced the activityof POD and CAT to reduce, may have a negative effect on plants, POD and CAT weresensitive to low concentrations of cadmium in soil.