Studies On Variation And Availability Of Nutrient Under Long-term Stationary Albic Soil In The Three River Plain

This paper deals with crop yield changes, variation and availability of nutrient under long-term different fertilization, culture, rotation and continuous cultivation in the Three River Plain albic soil with plot combining indoors experiment. The main contents include, a. The variation of crop yield and pH under long-term stationary experiment. b. The variation of total nitrogen, alkali hydrolysis-N, organic-N forms, N-supplying capacity, NO3--N, bio-availability of various nitrogen indexes. c. The variation of the forms of inorganic and organic phosphorus, the characteristics of phosphorus sorption and desorption, relative availability of various phosphorus forms. d. The contents of forms, variation and bio-availability of iron, manganese, copper and zinc. e. The variation of organic matter, the relationship between organic matter and nutrient. The main results obtained from this experiment is as follows: 1.The order of the mean crop yield of corn, soybean and wheat in different fertilization, culture, rotation and continuous cultivation are OM>NP>TS>CK, CT>DT>NT, rotation>continuous cultivation, respectively, and the level of significance of difference among them all attain 0.01. 2.Organic manure (except for successive planting soybean) can prevent pH value of albic soil descent. Whether rotation or continuous cultivation the pH value in successive planting soybean soil is the lowest, the soil pH has declined to 6 below. 3.The total nitrogen, phosphorus, iron, manganese, copper and zinc mean contents are 1840.80, 483.69, 20845.78, 620.94, 29.53 and 86.69 mg/kg, respectively. The hydrolizable nitrogen accounts for 70.23% of total nitrogen. The inorganic and organic phosphorus account for 52.56% and 47.44% of total phosphorus respectively. The order of contents in organic nitrogen, inorganic and organic phosphorus, iron, manganese, copper and zinc forms are as follows: HUN>amino acid N>ammonium N>amino sugar N, O-P>Fe-P>Al-P>Ca10-P>Ca2-P>Ca8-P, MLOP>MROP>LOP>HROP, RES-Fe>OX-Fe>OM-Fe > EX-Fe > CARB-Fe, OX-Mn > RES-Mn > OM-Mn > EX-Mn >CARB-Mn, RES-Cu > OM-Cu >CARB-Cu> OX-Cu> EX-Cu, RES-Zn >OX-Zn>OM-Zn>EX-Zn>CARB-Zn. 4.The contents of organic matter, total nitrogen, phosphorus, iron, mangan-ese, copper, zinc can be increased, and the contents of hydrolizable nitrogen and their forms (expect for ammonium N), Fe-P, Al-P, Ca2-P, all organic P forms, exchangeable and organic iron, manganese, copper, zinc are increased obviously in long-term application organic manure soil. Not only the contents of soil readily oxidizable carbon, humic acid, fuluic acid, and HA/FA value are increased and Kos value decreased but also the available nitrogen, phosphorus, iron, manganese, copper, zinc are kept more high level in the organic manure soils. Long-term mulching straw has similar role with organic manure for soil nutrient except for decreasing total phosphorus, available P, N and Ca2-P, but its fertilizer efficiency is not better than organic manure. Total nitrogen and phosphorus are enhanced, but Kos value, HA/FA, and organic matter reduced in long-term applying chemical fertilization. Organic matter and all kinds of nutrient are depleted in long-term no fertilization soil. 5.Long-term non-tillage is more beneficial to accumulate difficult oxidi-zable carbon, tight combining humus, total nitrogen, organic nitrogen forms, but available nitrogen and phosphorus is less than ploughing and subsoiling. In addition, non-tillage is superior to ploughing and subsoiling in retarding the contents of total iron, manganese,copper, and zinc,but in addition to manganese, the availability of iron, copper, and zinc is lower than the empress both. 6.No fertilization soil, the successive planting wheat compare to rotation and successive planting corn and soybean make organic matter, total nitrogen, phosphorus descent the range big, but the reduction of total iron, manganese, copper, zinc in rotation is the biggest. Because soil pH value is descended bigger in the successive planting soybean, soil available iron, manganese, copper and zinc is higher, but carbonate and oxide bound iron, manganese, copper and zinc are descended bigger, its Ca-P descended big, but Fe-P increased more. The total and loose combining humus, total nitrogen, various organic nitrogen forms, Fe-P, Al-P, organic bound iron, manganese, copper and zinc, readily oxidizable carbon, HA/FA value are descended the smallest in successive planting corn. 7.The order of contribution of hydrolizable N forms to crop nitrogen is, amino acid N (35.36%)>ammonium N (21.62%)>hydrolizable unidentified N (20.96%) > amino sugar N. Fe-P(22.84%) and Al-P(16.05%) have more contribution to crop phosphorus nutrition, and MLOP, MROP, LOP also have.8.In OM treatment soil, the nitrogen conversion to amino acid N is the biggest, phosphorus is transformed to Ca2-P, Al-P, Fe-P and organic P forms, and iron, manganese, copper, zinc to exchangeable and organic forms. In TS treatment soil, the nitrogen conversion to amino sugar N is the biggest, phosphorus is transformed to Fe-P, Al-P, MROP and HROP, and iron, manganese, copper, zinc also to exchangeable and organic forms. In NP treament soil, the nitrogen is transformed mainly to ammonium N, phosphorus to O-P, Al-P, Fe-P, MROP and HROP. 9.The soil NO3--N contents of seasonal variety is, going up gradually from May to the end of September to reach the highest and then descending in mulching straw, the other 3 kinds fertilization treatments reach the highest value in June, later descend gradually. The tendency of NO3--N contents of different culture are same alike, but the NO3--N contents are the lowest in non-tillage. 10.The organic nitrogen mineralization amount is increasing with incubated time, but gather speed tends to descend in aerobic condition, both the quantity of relation follow chemical reaction a class equation. The order of potential mineralization amount nitrogen(N0) in different treatment is OM(403.55 mg/kg)>TS(365.36 mg/kg)>NP(335.25 mg/kg)>NT(328.05 mg/kg)>DT(324.74 mg/kg)>CK(268.65 mg/kg). The half-life (t0.5) of OM treatment is more 4.12 weeks than CK. K value has no obvious difference in all treatments. 11. The capacity of phosphorus adsorption is stronger in low concentration, but it will become weak with phosphorus concentration's increasing. Their straight-line form data matches the square distance in langmuir. The capacity of phosphorus desorption is enhanced in long-term applying organic manure, but the capacity of phosphorus sorption decreased. The capacity of fixing phosphorus becomes stronger in long-term no fertilization. 12. The related analysis shows that hydrolizable-N, amino acid-N, amino sugar-N, ammonium-N, UHN, N0 value, mineralization N with the adsorption nitrogen amount of corn, wheat and soybean plants, Ca2-P, Al-P, Fe-P, LOP and MLOP with the adsorption phosphorus amount of three corps seeds, and available, exchangeable and most organic iron, manganese, copper and zinc with adsorption of three crops seeds have significant or very significant positive relation.13. The results of path analysis shows that the order of direction effect of various organic nitrogen forms to alkali hydrolysis-N is amino acid N>amino sugar N>ammonium N>UHN, various inorganic and organic phosphorus forms to available phosphorus is Fe-P>Al-P>Ca2-P>Ca8-P>MLOP>LOP. The direction effect of Ca10-P, O-P, MROP and HROP to available phosphorus is little. The effect of exchangeable forms to available iron, manganese, copper and zinc is the biggest, and the organic form is the next . The oxide bound iron, copper to available iron, copper and carbonate bound manganese, zinc to available manganese, zinc has positive effect, but residual iron, copper to available iron, copper and oxide bound manganese to available manganese have negative effect. 14. Available nitrogen, phosphorus, iron, manganese, copper and zinc related significantly or very significantly to readily oxidizable carbon, humic acid, fulvic acid and loose combining humus. Each form of hydrolizable N(except for ammonium N) related significantly or very significantly to total organic matter, readily oxidizable carbon, humic acid, fulvic acid. The effect of organic matter to organic phosphorus is bigger than that of inorganic phosphorus. Total (without iron) manganese, copper, zinc, organic and exchangeable iron, manganese, copper and zinc related significantly to organic matter, readily oxidizable carbon, humic acid, fulvic acid.