2002 6 13 6 CHIN ESE JOURNAL OF APPL IED ECOLO GY,J un. 2002,13 (6) 709 714 3 3 3 (, 210095) C,,,, C., C ;,C., C., C. 300g kg - 1 500g kg - 1, C, 200g kg - 1,., C. 1001-9332 (2002) 06-0709 - 06 S153. 621 A Influence of environmental factors on the decomposition of organic carbon in agricultural soils. HUAN G Yao, L IU Shiliang,SHEN Qirong and ZON G Lianggang ( College of Resource and Environmental Sciences, N anjing A gricultural U niversity, N anjing 210095). 2Chin. J. A ppl. Ecol.,2002,13 (6) :709 714. To quantitatively investigate the effects of environmental factors on organic carbon decomposition, CO 2 2C was measured from the incubation of wheat and rice straw as well as their roots mixed with a paddy soil over a 902day period. Results showed that decomposition of the straw carbon was faster than that of the roots. Amount of CO 2 2C released from the organic matter decomposition was quantitatively related to its properties of C/ N ratio. Increase of temperature within a lower temperature range enhanced greatly the decomposition while such an enhancement weakened within a higher temperature range. Under the moist condition, the temperature coefficient of organic carbon decomposition declined exponentially with the incubation time. The temperature coefficient did not significantly decrease with the time for the submerged condition after one2week incubation. The effect of water status showed that the decomposition at the water contents of 300g kg - 1 and 500g kg - 1 was faster than that under the treatments of 200g kg - 1 and the submerged. Within the first month period of incubation,carbon released from the incubation of wheat straw was negatively related to the clay fraction of the soils. Key words Environmental factors, Organic carbon decomposition, Agricultural soils, Incubation experiment, Climate change. 1, CO 2. 115 10 15 kg C, [2,16,21 ], CO 2 CO 2 [17 ]. CO 2 ( ). CO 2 [5,10,14 ],, CO 2., [8 ],. C [7 ] [4,6 ] [3,19 ] [12 ].. C., C [8,13,14,20 ],C. C CO 2, C. 2 211, 20, 1. 3 (39830220). 3 3. 2000-04 - 29,2000-08 - 27.
710 13 C, C.,2. 1 Table 1 Physical and chemical properties of soils used Sampling location p H ( H 2 O) C N Total C Total N (g kg - 1 ) (g kg - 1 ) C/ N < 01005mm clay content Hongta, Yixing 5152 17152 1172 1012 35191 Dapu Yangwei 5183 9169 1130 715 16150 Yangxi Xindu 6115 8124 1113 713 20181 Mingling Ganli 5176 10173 1136 719 31133 Xinzhuang Tangjiao 6120 14150 1151 916 41129 Fenshui Honghu 6136 8129 1104 810 46125 Youtang Lidu 5118 15120 1167 911 58113. 30d,.,C. [11 ], C, ( ) ( ). C,. 2,,. 2 Table 2 Properties of organic materials used( g kg - 1 ) Organic materials C N C/ N Lignin Wheat straw 394 4199 7910 171 Wheat root 413 6165 6211 203 Rice straw 344 7158 4513 135 Rice root 419 11118 3715 165 212 Bartha [1 ], 650ml, NaOH C CO 2. NaOH,CO 2 2C., 100g. 3 6mm, 70, 1g.,.. 12 24 36, 3. 4 ( ) 200 300 500g kg - 1, 3 50 % 60 % 70 % 80 %.,. C 36-01033 MPa,.,. 3 311 C 4 300g kg - 1 24 CO 2 1, C 2. 1,CO 2,, > > >. 2, ( 0 30d), C,,, 1 CO 2 Fig. 1 Cumulative of carbon mineralized from different organic materials in paddy soil. 1 Rice straw, 1 Rice root, 1 Wheat straw, 1 Wheat root. The same below. 2 C Fig. 2 Decomposition rate of carbon from different organic materials., C C. 3 4 C, C. 3, 90d, C C 50 %, C 30 %. 30d, C C 30 %, C 20 %.,C/ N C,. C ( Y ) C/ N ( L ) :
6 : 711 3 C ( C %) 3 Table 3 Amount of CO 2 2C released from the decomposition of different organic materials ( % of added C) Organic materials C 0 30 rate C 31 60 Incubation periods (d) rate C 61 90 rate C 0 90 decomposed Wheat straw 14113 3519 3619 914 3414 817 21216 5410 Wheat root 8014 1915 3518 817 2616 614 14218 3416 Rice straw 11510 3314 3415 1010 1818 515 16813 4910 Rice root 6118 1418 3110 714 2418 519 11716 2810 3 24, 300g kg - 1. Incubated at 24 and water content of 300g kg - 1. Y = a + b[c/ N ]/ L (1), a b,. ( 4),, C,. 90d, (1). 4 Y = a + b[ ( C/ N) / L] Table 4 Parameters and statistical testing for the equation of Y = a + b [ ( C/ N) / L] Incubation periods(d) a (mg C ) b (mg C ) 0 30-1611 34719 019570 3 31 60 2710 2216 018595 61 90 1215 4112 016247 0 90 2314 41117 019909 3 3, N C/ N.,. (C / C ) [22 ],,C/ N ; C/ N,. (C/ N 5110, 132g kg - 1 ) ( C/ N 1118, 135g kg - 1 ) ( C/ N 1112, 202g kg - 1 ) 0119 0130 0143. N C/ N. 312 C (300g kg - 1 ) CO 2 3. 3,12 C,, 90d. 24 36, ( 15d) C,. 5 12 24 36,4, r C C. 12 24,30d C 1183 2109 ;24 36, C 1137 1145.,, C ;,C. [6,9 ]. 3 CO 2 Fig. 3 Cumulative of carbon mineralized from wheat straw in paddy soil at different temperatures. 5, (0 30d) C,, C. C, ( ) 4 Q 10.,,C 2, 114 0125. 3, 90d,. Q 10, 215,, Q 10, 30d, Q 10 1.,,, C ( Q 10 1). 4
712 13 5 C 3 Table 5 Amount of CO 2 2C released from incubation experiments at three temperature levels Organic materials Incubation temperature ( ) C 0 30 increment Incubation periods (d) C 31 60 increment C 61 90 increment 12 9519-6916 - 4915 - Wheat straw 24 17517 183 7110 102 4916 100 36 25411 145 8019 114 7117 145 12 6311-5313 - 3610 - Wheat root 24 13118 209 6110 114 4116 116 36 18014 137 6310 103 4918 120 3 C The decomposed implies the of CO 2 2C released from the organic materials and the soil.., C Q 10 t (d) : Q 10 = 0192exp (616/ t) (0 < t 90) ( r = 019638 3 3, n = 11) (2) 4 Fig. 4 Change of temperature coefficient with incubation time. Submerged,. Moist, Exponential fit., C [6,9 ], 5., C. ( Substrate sources),,,,( ).,,,, C. 313 C (24 ) C 5. 5, 90d, 300 500g kg - 1, C,, 200g kg - 1.,. 5 CO 2 Fig. 5 Cumulative of carbon mineralized from wheat straw in paddy soil with different water content. 1) 200g1kg - 1,2) 300g kg - 1,3) 500g kg - 1,4) Submerged. The same below. C. 6 24, C. 6,,C, 300 500g kg - 1 : C 34 %,C 17 %. 200g kg - 1, C 20 %, C 10 %., C, C. 90d, 4 (200 300 500g kg - 1 ) C 42 51 54 36 %, C 29 31 33 15 %. 12 36 6. [3 ], 2 15g kg - 1,C
6 : 713 6 C ( C %) 3 Table 6 Amount of CO 2 2C released from the decomposition of organic materials at different water status ( % of added C) Organic materials Water content (g kg - 1 ) C 0 30 rate C Incubation periods (d) 31 60 rate C 61 90 rate C 0 90 rate 200 117155 29184 45147 11154 22137 5168 185139 47105 Wheat straw 300 141127 35186 36187 9136 34145 8174 212159 53196 500 122162 31112 49175 12163 43102 10192 215140 54167 Submerged 46109 11170 50144 12180 33100 8138 129153 32188 200 71181 17139 39164 9160 16145 3198 127190 30197 Wheat root 300 80139 19146 35182 8167 26159 6144 142179 34157 500 87162 21122 42111 10120 32106 7176 161179 39117 Submerged 14128 3146 24148 5193 24149 5193 63126 15132 200 88190 25184 27143 7197 11178 3142 128111 37124 Rice straw 300 115103 33144 34149 10103 18179 5146 168131 48193 500 123197 36104 35195 10145 24110 7101 184101 53149 Submerged 50161 14171 53191 15167 28167 8133 133118 38172 200 66122 15180 35145 8146 15132 3166 116199 27192 Rice root 300 61184 14176 31103 7141 24176 5191 117163 28107 500 54199 13112 33104 7189 24192 5195 112196 26196 Submerged 17134 4114 20152 4190 22123 5131 60109 14134 3 24 Incubated at 24. (70 %WHC).,., C,> 500g kg - 1 > 300g kg - 1 > 200g kg - 1 ( 6).. 7 3 C, 8 3 (0 30d 31 60d 61 90d) C. 8, 90d, C,. Y = 287-7317 X ( r = 019223 3 3, n = 6) (3), Y ( mgc), X 6 C Fig. 6 Cumulative of carbon mineralized from paddy soil with different water content. 314 C,,., C, ( ) [15,18 ].,,. ( 1) (10g kg - 1,36, - 01033MPa ),, C, 7 CO 2 Fig. 7 Cumulative of carbon mineralized from wheat straw in paddy soils with different clay contents. 1) 165g kg - 1,2) 313g kg - 1,3) 463g kg - 1. 8 C Fig. 8 Relationship between carbon mineralized from wheat straw in paddy soils and soil clay content. 1) 0 30d,2) 31 60d,3) 61 90d.
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