Studies On Fertility Evolution And Sustainable Utilization Of Fluvo-aquic Soil Under Different Long-term Fertilization Patterns

Based on "Chinese Fluvo-aquic Soil Fertility and Fertilizer Efficiency Long-term Monitoring Base", 9 Fertilization Patterns usually used in Henna province, comprised of various fertilization patterns including unbalanced fertilization such as fertilizers alone(N), no nitrogen fertilizers but phosphate and potassium(PK), no phosphate but nitrogen and potassium fertilizers combined(NK), no potassium but nitrogen and phosphate fertilizers combined(NP);manure and fertilizers combined(MNPK,1.5MNPK), straw returning (SNPK)were evaluated from 1990 (1)to study the soil nutrients fertility evolution of Fluvo-aquic soil;(2) to monitor the resource and its amount of soil nutrients from environment ,estimate the contribution of nutrients to crops ,measure the fates of nutrient in soil ; (3) to compare the nutrient efficiency; (4) to understand factors influenced the yield of wheat and maize and their affected extent; (5) to choose the excellent fertilization patterns to safeguard soil sustainable utilization .The main results were:1,Had known the exhaustion evolution of soil nutrients in unbalanced fertilization ,and forwarded the amended methods for different soil degradation styles.Long-term unbalanced fertilization for example,applied nitrogen fertilizer alone(N),or no nitrogen fertilizers but phosphate and potassium(PK),or no phosphate but nitrogen and potassium fertilizers combined(NK),these fertilization patterns made some nutrients in soil built quickly(the Olsen-P content increased 1.04,1.6 mg·kg^-1 annually in NP,PK treatments, exchangeable-K content increased 3.36,4.96 annually in NK,PK), in the same time exhausted some nutrients which had not supplemented, resulted in the ratio among nutrients losing balance.The N:P:K ratio changed from 13.6:1:17.2 in 1990 in N treatment to 33.6:1:36.4 after 15 years N fertilization alone, correspondingly, N:P:K ratio changed from 6.6:1:10.5 to 26.4:1:59 in NK treatment, and 11.3:1:16.2 to 2.4:1:6.6 in PK treatment. Another result was soil productivity decreased 45.8%,42.8% and 71% respectively. Forwarded relevant amended methods for different soil degradation styles.Manure and fertilizers combined could increase the content in soil sustained and remarkable. The organic matter content increase 0.3723,0.2204,0.2365 and 0.2343 g·kg^-1 per year averagely, the evolution models of organic matter in 4 treatments were Y_1.5MNPK=0.3723x+12.421(R²=0.8593), Y_MNPK=0.2204x+12.906 (R²=0.6941), Y_SNPK=0.2365x+11.765(R²=0.9075),Y_MNPK2=0.2343x+13.274(R²=0.72) respectively. Corresponded, the total N content increased 0.0222,0.0196,0.0096,0.0172 g·kg^-1 annually, and the evolution models were Y_1.5MNPK=0.0222X+0.7143(R²=0.8674), Y_MNPK=0.0196x+0.683(R²=0.9636), Y_SNPK=0.0096x+0.7053(R²=0.5678), Y_MNPK2=0.0172x+0.6618(R²=0.8513).2,Had explored the rule of some nutrients,mainly Olsen-P and exchangeable-K moving regular in soil,and found the threshold value of Olsen-P and exchangeable-K content for leaching in light loam Fluvo-aquic soil.The applied rate of P was 239 kg·ha^-1 annually and the rule of Olsen-P content in soil was: y=6.1999x+1.0018(R²=0.9771) in 1.5MNPK (Manure applied with fertilizers),Olsen-P content increased 1.3 mg·kg^-1 per 50 kg·ha^-1 applied into soil annually; similarly,y=4.6449x+1.7115(R²=0.9862)in MNPK treatment,in which the P applied rate were 159.3 kg·ha^-1 year^-1; maize straw turning(SNPK) had less effect on Olsen-p than manure, y=1.5926x+5.0051 (R²=0.854) under the applied rate of P 104 kg·ha^-1.Long-term applyyed fertilizers and manure could result in the leaching of phosphate.The manure could increase the Olsen-p content accumulating rate 33.5%-50% faster than phosphate applying, on the contrary, maize straw could decrease 21.5%. The Olsen-p started to leach when it more than 40 mg·kg^-1 in 0-20cm soil layer. The threshold value of save and effective Olsen-P content was 40 mg·kg^-1.The applied rate of K was 418 kg·ha^-1 and 291 kg·ha^-1 annually in 1.5MNPK and MNPK treatments, the rules of exchangeable-K content variation in soil was: Y_1.5MNPK=10.34X+41.73(R²=0.9553) and Y_MNPK=7.2176x+46.549(R²=0.8119),exchangeable-K content increased 1.24 mg·kg^-1 per 50 kg·ha^-1K applied into soil annually in both treatments; maize straw turning(SNPK) had less effect on exchangeable-K than manure, Y_SNPK=3.592X+62.652 (R²=0.676)under the applied rate of K 325 kg·ha^-1.The exchangeable-K started to move down when it more than 180 mg·kg^-1 in 0-20cm soil layer. The threshold value of exchangeable-K content for leaching in light loam was 180 mg·kg^-1.3,Had calculated the budget of nitrogen in soil and the circle in biological systemThe soil received 24 kg·ha^-1 from rainfall and irrigation, wheat residue and seed, averaged 84 kg·ha^-1 were recovered by wheat and maize, resulted in 58.6～63.7 kg·ha^-1 negative balance annually in treatments without N fertilizer applied during 1990-2004; In all N fertilization treatments N remained in 0～40cm soil layer, there were about 418 kg·ha^-1 nitrogen,75% of total N entered accumulated in soil annually in 1.5MNPK treatment. Averaged 63% of nitrogen entered soil in maize straw returning treatment. Among three fates there were 47.8%å’Œ48.8% recovered by wheat and maize, 9.7% residued in 0-40cm soill,55% loss in different ways in NPK and NP treatments.Manure companied with fertilizers(MNPK)had higher recovery rate, residue rate and the lowest loss rate, were 38.1～44.3%, 16.8～23% and 51% respectively; With the increasing of the amount of manure and fertilizer applied,the recovery rate decreased, and loss rate increased; N loss rate in NK treatment was the highest and the lowest in MNPK treatment, the former was almost 3.5 times as the latter.4,Had calculated budget of phosphate nutrient in soil and its circling in biological systemThe mean inputs of phosphate from wheat residue and seed was 2.3～3.1kg·ha^-1, and P 16.7～22 kg·ha^-1 were recoverd by wheat and maize, resulted in 14.4-18.9 kg·ha^-1 negative balance of the P nutrient annually in treatments without P fertilizers applied after 15 years wheat-maize rotation; Except fertilizer P 78 kg·ha^-1 and 107 kg·ha^-1 (1.5MNPK), the P nutrient from manure, maize strew, rain water and irrigations, seeds were about 2.7-134 kg·ha^-1,totally 1130～3509 kg·ha^-1 phosphate entered soil, appropriately 75.2%～85.5% accumulated in 0-40 cm soil annually, the more the amount of P nutrient input, the higher the P accumulated in soil, in which 38.6～60% transformed into soil total P(H₂SO₄-HClO₄method), 6.7～13.6% transformed into available-P with more in manure and less in inorganic fertilization treatments, at lest 40～62% of phosphate were extravagant.5,Calculated budget of potassium nutrient in soil and its circling in biological systemThe mean inputs of potassium from manure, maize straw, rain water irrigations, and seeds were about was 21～29.6kg·ha^-1, average of K 90 kg·ha^-1 recovered by wheat and maize, resulted in negative the apparent and actual balance of the K nutrient, 49.3～111.3 kg·ha^-1 lost annually in treatments without K fertilizers applied after 15 years in wheat-maize rotation.Except fertilizer K146kg·ha^-1(MNPK)and218 kg·ha^-1(1.5MNPK), the K nutrient from environment were about 75.3～234 kg·ha^-1 entered soil, appropriately K 56.2～200 kg·ha^-1 accumulated in 0-40cm soil annually, the more the amount of K nutrient input, the higher the K accumulated in soil; 5.2%-13.4% changed into exchangeable-K with more in manure and less, the sequence was: MNPK＞NPK＞1.5MNPK＞SNPK＞PK＞NK6,Analyzed the factors affected the yield of wheat and maize;calculated the N P K recovered efficiency entered soil during 15 experimental years, and defined the minimum fixed number of years to assess the fertilizer recovered efficiency scientifically.Among five factors (fertilization patterns, soil fertility, climate, crop variety and rotations) affected wheat yields, fertilization influenced the largest extent,. The affected extent was 72.6%／82.7%;Soil fertility affected in range of 34%-53%, averaged 44%;The impact of climate varied with fertilization type and rate from 21.2% to 64.7%, ranged the third.Climates influenced the largest extent on maize yield in 15 years, varied from 85% to 115% with the mean was 87%,Fertilization influenced 52%～81%,ranged the second, the effective extent changed with years irregularly; Soil fertility affected the maize yield in the range of 49%～69%, averaged 60%. It needed at least 5 years to assess the fertilizer recovered efficiency scientifically.In brief, we synthesized the effect of cultivating soil fertility, fertilizer recovered efficiency, economic efficiency, and biological and environment risk from the long run to compare the main fertilization patterns used in henna agriculture, SNPK was the excellent fertilization, NPK the second. 1.5MNPK had the highest risk for biological and environment, it should be used two years a time or reduced the amount of manure applied. PK,N,NK fertilization patterns should be stopped.