苜蓿草地与苜蓿-作物轮作系统土壤微生物量与土壤轻组碳氮研究

从2000年10月到2004年4月，通过大田试验研究了半干旱黄土高原地区，苜蓿草地、苜蓿-作物轮作农田以及常规耕作农田中土壤有机碳、土壤全氮、土壤微生物生物量与土壤轻组物质的变化规律。结果表明，土壤轻组有机碳和氮含量苜蓿-作物轮作系统高于苜蓿草地。土壤微生物量碳和氮，以及它们占土壤有机碳和土壤全氮的比苜蓿-作物轮作系统高于常规耕作农田。土壤呼吸商苜蓿-作物轮作系统低于苜蓿草地和常规耕作农田。14年生苜蓿草地土壤微生物含量高，分解腐化植物碎片的能力高，但土壤有机物质利用不经济，3年中土壤全氮含量并无显著增加，这说明该系统较高的物质循环能力仅维持高的土壤肥力，而不能继续提高土壤肥力。苜蓿-作物用地系统不但能克服长时间种植苜蓿造成的物质循环的浪费，而且维持了良好的土壤肥力，促进了土壤氮素的有效利用。     

Microbial biomass and microbial C:N ratio in bulk soil and buried bags for evaluating in situ net N mineralization in agricultural soils

The in situ net nitrogen mineralization (N_net) was estimated in five agricultural soils under different durations of organic farming by incubating soil samples in buried bags. Simultaneously, soil microbial C and N was determined in buried bags and in bulk soil under winter wheat and after harvest. The aim was to check for variations in soil microbial biomass contents and microbial C:N ratios during the incubation period, and their importance for N_net rates. Microbial C and N contents were highest in soils that had been organically farmed for 41 years, whereas N_net rates were highest in a short‐term organically managed soil that had been under grassland use until 36 years ago. The mean coefficient of variation in the bulk soil for microbial C estimates ranged from 5 to 12 %. Microbial N contents were similar inside buried bags and in the bulk soil at the end of the incubation periods. Under winter wheat during the incubation period until harvest, microbial C contents and microbial C:N ratios (in 10—27 cm depth only) decreased more strongly inside buried bags than in the bulk soil. Following harvest of winter wheat and ploughing, microbial biomass increased while in situ N_net decreased, presumably due to N immobilization. The N_net rates were not correlated with microbial N contents or changes in microbial N contents inside buried bags. At the end of the vegetation period of winter wheat, N_net rates were negatively correlated with microbial C:N ratios. Because these ratios concurrently decreased more inside buried bags than in the bulk soil, the N_net estimates of the buried bag method may differ from the N_net rates in the bulk soil at that time.     

不同节水稻作模式对土壤微生物数量和微生物量碳氮的影响

针对南方丘陵区季节性干旱这一区域问题,以节水稻作模式为研究对象,以常规稻作模式为对照,通过田间定位试验,研究了稻基农田土壤微生物数量和土壤微生物量碳氮的变化规律.结果表明,与该区常规稻作模式相比,节水稻作模式的土壤微生物数量和土壤微生物量碳氮差异显著;节水稻作模式有利于土壤细菌和放线菌的增殖,但抑制了真菌的增殖;土壤微生物量碳和微生物量氮的显著增加,以水旱轮作双季稻模式最佳,说明采用节水稻作模式可有效提升土壤细菌数量、放线菌数量、微生物量碳和微生物量氮含量.因此,在南方丘陵季节性干旱区,采用节水稻作模式,可促进稻田生态系统健康持续发展.     

添加莠去津的土壤中微生物生物量碳、氮、磷对外源有机无机物质的动态响应

研究了添加有机、无机营养物质对外加除草剂莠去津土壤(每1g土中含莠去津10mg/)中微生物生物量碳、氮和磷的动态变化过程。研究结果表明,在整个培养过程中,仅加莠去津的土壤中微生物生物量碳、氮、磷的含量均显著降低,与对照相比,分别平均降低了13.5%,10.1%,20.0%。但是,施用有机、无机营养物质的处理,土壤微生物生物量碳、氮、磷的含量均显著增加。不同处理对微生物生物量碳、氮的含量影响程度依次为:腐熟猪粪>紫云英>水稻秸秆腐熟猪粪>N、P肥配施>单施N肥>单施P肥。而对微生物生物量磷含量的影响则为:腐熟猪粪>N、P肥配施>紫云英>单施N肥>单施P肥>水稻秸秆。     

Influence of Plant Residues after Steam-Treatment with High Temperature and Pressure on Soil Microbial Biomass C and N, Water-Soluble C and N, and pH

Steam-treated grass trimmings (GrT), and wooden chips of pine (PnT) and walnut branches (WnT) or non-treated grass trimmings (GrNoT) and wooden chips of pine (PnNoT) and walnut branches (WnNoT) were mixed with soil (S) and then incubated for 10 weeks to measure microbial biomass C (MBC) and N (MBN), water-soluble C (WSC) and N (WSN), and soil pH. The results showed that there were a larger amount of MBC and WSC in steam-treated samples, principally in early period. It was probably due to the steam-treatment facilitating solubilization of organic C that served with substrate for microbial biomass. In grass trimming, the MBN and WSN had differences between treated and non-treated. No such differences in wooden chips was probably because the low total N content in these plants. The higher value of WSN showed in S+GnNoT showed more potential of nitrate pollution. The steam-treatment did not influence on soil pH after 1 week of incubation.     

Land use effects on the dynamics of soil C, N and microbes in the water-wind erosion crisscross region of the northern Loess Plateau, China

The water-wind erosion crisscross region of the northern Loess Plateau in China is under constant pressure from severe erosion due to its windy and dry climate and intensive human activities. Identifying sustainable land use patterns is key to maintaining ecosystem sustainability in the area. Our aim was to appraise the impacts of different land use regimes on the dynamics of soil total organic C(TOC), total N(TN), and microbes in a typical watershed in the northern Loess Plateau to identify sui...     

有机物料输入稻田提高土壤微生物碳氮及可溶性有机碳氮

土壤微生物量碳、氮和可溶性有机碳、氮是土壤碳、氮库中最活跃的组分,是反应土壤被干扰程度的重要灵敏性指标,通过设置相同有机碳施用量下不同有机物料处理的田间试验,研究了有机物料添加下土壤微生物量碳（soil microbial biomass carbon,MBC）、氮（soil microbial biomass nitrogen,MBN）和可溶性有机碳（dissolved organic carbon,DOC）、氮（dissolved organic nitrogen,DON）的变化特征及相互关系。结果表明化肥和生物碳、玉米秸秆、鲜牛粪或松针配施下土壤微生物量碳、氮和可溶性有机碳、氮显著大于不施肥处理（no fertilization,CK）和单施化肥处理,分别比不施肥处理和单施化肥平均高23.52%和12.66%（MBC）、42.68%和24.02%（MBN）、14.70%和9.99%（DOC）、22.32%和21.79%（DON）。化肥和有机物料配施处理中,化肥+鲜牛粪处理的微生物量碳、氮和可溶性有机碳、氮最高,比CK高26.20%（MBC）、49.54%（MBN）、19.29%（DOC）和32.81%（DON）,其次是化肥+生物碳或化肥+玉米秸秆处理,而化肥+松针处理最低。土壤可溶性有机碳质量分数（308.87 mg/kg）小于微生物量碳（474.71 mg/kg）,而可溶性有机氮质量分数（53.07 mg/kg）要大于微生物量氮（34.79 mg/kg）。与不施肥处理相比,化肥和有机物料配施显著降低MBC/MBN和DOC/DON,降低率分别为24.57%和7.71%。MBC和DOC、MBN和DON随着土壤有机碳（soil organic carbon,SOC）、全氮（total nitrogen,TN）的增加呈显著线性增加。MBC、MBN、DOC、DON、DOC+MBC和DON+MBN之间呈极显著正相关（P<0.01）。从相关程度看,DOC+MBC和DON+MBN较MBC、DOC、MBN、DON更能反映土壤中活性有机碳和氮库的变化,成为评价土壤肥力及质量的更有效指标。结果可为提高洱海流域农田土壤肥力,增强土壤固氮效果,减少土壤中氮素流失,保护洱海水质安全提供科学依据。     

Microbial biomass in arable soils of Germany during the growth period of annual crops

Results from several field studies involving numerous measurements were used to describe the change of soil microbial biomass C (C_mic) and N (N_mic) during the growth period of annual crops (years 1988–1992, 1994, 1995) under the temperate climatic conditions of central Europe. The data were taken from our own investigations as well as from the literature. Only studies with at least eight measurements on one plot during the growth period were used. The total number of farms (cash crop–production farms) was 7, that of experimental plots was 15. The evaluation of these results through regression analysis demonstrated that C_mic and N_mic from the beginning of a year increased only slightly until summer and subsequently decreased until autumn to their initial levels. This increase on an average corresponded to a C assimilation of approx. 100 kg ha^–1 and an N immobilization of approx. 20 kg ha^–1 (30 cm)^–1. The increase in N_mic alone could not explain N immobilization rates frequently observed in different studies using ¹⁵N‐labeled fertilizers. Most of the labeled N that was immobilized (>50 kg N ha^–1) might have accumulated in the matrix of soil organic matter (SOM). Therefore, the changes in microbial biomass may be of less importance for changes in soil N storage as frequently assumed.     

冬季作物对水稻生育期土壤微生物量碳、氮的影响

选取我国南方4种冬季作物黑麦草、紫云英、油菜、马铃薯,以冬闲田作对照,对水稻生育期土壤微生物量碳（SMBC）和土壤微生物量氮（SMBN）的短期内动态变化进行了研究。结果表明,早稻田翻耕前,冬季作物处理土壤SMBC和SMBN与冬闲田存在显著差异(P0.05),黑麦草处理SMBC为398.5 mg/kg,显著高于其他作物;紫云英处理SMBN最高,为97.8 mg/kg。在早稻整个生育期,黑麦草处理SMBC显著高于其他处理,晚稻生长过程中各处理无显著差异。冬季作物对稻田土壤微生物商(MQ)的影响,随着水稻生长发育进程有不同程度的变化,黑麦草处理在早稻整个生育期高于冬闲田。     

造林恢复植被后土壤的化学计量学特征对其碳组分的影响

Afforestation is recognized as an important driving force for soil organic C(SOC) dynamics and soil element cycling.To evaluate the relationships between soil C:N:P stoichiometry and SOC fractions,soil C:N:P stoichiometry distributions at 0–200 cm soil depths were analyzed and the contents of SOC fractions were evaluated in 9 typical land-use systems on the Loess Plateau of China.The contents of light fraction organic C,particulate organic C(53,53–2 000,and2 000 μm),labile organic C,microbial biomass C,and dissolved organic C decreased with increasing soil depth and were higher in afforested soil than in slope cropland soil.Compared with the slope cropland,different vegetation types influenced soil C:N,C:P,and N:P ratios,especially when C:P and N:P ratios were significantly higher(P0.05).Moreover,SOC fractions at the 0–10 and 10–40 cm depths were particularly affected by soil C:P ratio,whereas those at the 40–100 and 100–200 cm soil depths were significantly affected(P0.05) by soil N:P ratio.These results indicate that changes in SOC fractions are largely driven by soil C:P and N:P ratios at different soil depths after afforestation.     

生物质炭与氮肥配施对旱地红壤微生物量碳、氮和碳氮比的影响

以江西典型旱地红壤为研究对象,设置生物质炭和氮肥2个因素(生物质炭4个水平分别为0t/hm~2,5t/hm~2,20t/hm~2,40t/hm~2;氮肥4个水平分别为0kg/hm~2,60kg/hm~2,90kg/hm~2,120kg/hm~2),研究了生物质炭施入大田3a后对旱地红壤微生物量碳、氮及碳氮比的影响。结果表明:与对照相比,生物质炭与氮肥配施有效地提高了土壤微生物量碳,提高幅度为18.22%~122.74%,对土壤微生物量氮的提高效果更为明显,提高幅度为20.86%~312.91%。生物质炭与氮肥配施后土壤微生物碳氮比有不同程度的降低,降低幅度为18.11%~51.56%,其中以20t/hm~2生物质炭与60kg/hm~2氮肥以及40t/hm~2生物质炭与120kg/hm~2氮肥的比例施用后对微生物碳氮比的降低效果最为明显。因此,通过生物质炭与氮肥配施可以提高旱地红壤中微生物量碳、氮及土壤氮素生物活性。     

长期稻秆还田对土壤微生物量及C、N动力学的影响

A study was performed on the long-term effect of straw incorporation on soil microbial biomass C contents, C and N dynamics in both Rothamsted and Woburn soils. The results showed that for both soils, the microbial biomass C contents were significantly different among all the treatments, and followed the sequence in treatments of straw chopped and incorporated into 10 cm (CI10) > straw burnt and incorporated into 10 cm (BI10) > straw chopped and incorporated into 20 cm (CI20) > straw burnt and incorporated into 20 cm (BI20). Laboratory incubation of soils showed that the cumulative CO₂ evolution was closely related to the soil microbial biomass C content. Carbon dioxide evolution rates (CO₂-C, μg (g•d)^-1) decreased rapidly in the first two weeks' incubation, then decreased more slowly. The initial K₂SO₄-extractable NH₄-N and NO₃-N contents were low and similar in all the treatments, and all increased gradually with the incubation time. However, net N immobilization was observed in chopped treatments for Rothamsted soils during the first 4 weeks. Nevertheless, more N mineralization occurred in Treatment CI10 than any other treatment at the end of incubation for both soils. The Woburn soils could more easily suffer from the leaching of nitrate because the soils were more permeable and more N was mineralized during the incubation compared to the Rothamsted soils.     

鸡粪与化肥不同配比对杨树苗根际土壤酶和微生物量碳、氮变化的影响

为比较鸡粪有机肥与化肥以不同比例配施对杨树苗根际土壤环境的作用效果,通过盆栽试验,研究了N100（尿素提供100%的氮）、 M10N90（鸡粪和尿素分别提供10%和90%的氮)、 M30N70（鸡粪和尿素分别提供30%和70%的氮）和M50N50（鸡粪和尿素各提供50%的氮）等处理对一年生杨树苗根际土壤酶活性、 微生物量碳（SMBC）和微生物量氮（SMBN）的影响。结果表明, 同N100处理相比,M30N70处理的杨树苗根际土壤脲酶、 碱性磷酸酶、 过氧化氢酶和蔗糖酶活性分别提高14.41%~26.49%、 13.87%~27.93%、 12.07%~27.08%和29.17%~46.43%; 根际SMBC、 SMBN含量分别提高63.00%~76.62%、 40.01%~90.38%。在杨树苗的年生长过程中,根际土壤脲酶、 碱性磷酸酶、 过氧化氢酶和蔗糖酶活性均在施肥后120 d 最高; 而根际SMBC和SMBN含量分别在施肥后90 d和30 d达到最大值。随着杨树苗的生长发育,SMBN含量逐渐降低,而在落叶期有一定的回升。与M30N70处理相比,M10N90和M50N50处理对杨树苗根际土壤酶和微生物量碳、 氮的影响较小。综合分析认为,鸡粪有机肥与化肥以3∶7比例配施对杨树苗根际区域生态环境的改善效果最佳。     

稻田系统管理措施对微生物生物量C、N、P的长期影响

A 12-year field experiment was conducted to investigate the effect of different tillage methods and fertil-ization systems on microbial biomass C,N and P of a gray fluvo-aguic soil in rice-based cropping system .Five fertilization treatments were designed under conventional tillae(CT) or on tillage(NT) system:no fertilizer(CK) ; chemical fertilizer only(CF) ; combining chemical fertilizer with pig manure(PM); combining chemical fertilizer with crop straw (CS) and fallow (F). The results showed that biomass C,N and P were enriched in the surface layer of no-tilled soil,whereas they distributed relatively evenly in the tilled soil,which might result from enrichment of crop resdue,organic manure and mineral fertilzer,and surficial developent of root systems under NT.Under the cultivation system NT had slightly greater biomass C,N and P at 0-5 cm depth ,significantly less biomass C,N and P at 5-15 cm depth ,less microbial biomass C,N and equivalent biomass P at 15-30 cm depth as compared to CT,indicating hat tillage was beneficial for the multiplication of organims in the plowed layer of soil.Under the fallow system,biomass C,N and P in the surface layer were significantly greater for NT than CT while their differences between the two tillage methods were neligible in the deeper layers.In the surface layer,biomass C,N and P in the soils amended with oranic manure combined with mineral fertilizers were significantly greater than those of the treatments only with mineral fertilizers and the control.Soils without fertilzer had the least biomass nutrient contents among the five fertilization treatments.Obviously,the long-term application of organic manure could maintain the higher activity of microorganisms in soils.The amounts of biomass C,N and P in the fallowed soils varied with the tillage methods;they were much greater under NT than under CT,especially in the surface layer,suggesting that the frequent plowing could decrease the content of organic matter in the surface layer of the fallowed soil.     

黄土高原某些耕作土壤中土壤微生物生物量C、N与矿化N的关系

The chloroform fumigation-incubation method was used to measure the soil microbial biomass C (SMBC) and N (SMBN) in 16 loessial soils sampled from Ansai, Yongshou and Yangling in Shaanxi Province. The SMBC contents in the soils ranged from 75.9 to 301.0 μg C g^-1 with an average of 206.1 μg C g^-1, accounting for 1.36%~6.24% of the total soil organic C with an average of 3.07%, and the SMBN contents from 0.51 to 68.40 μg N g^-1 with an average of 29.4 μg N g^-1, accounting for 0.20%~5.65% of the total N in the soils with an average of 3.36%. A close relationship was found between SMBC and SMBN, and they both were positively correlated with total organic C, total N, NaOH hydrolizable N and mineralizable N. These results confirmed that soil microbial biomass had a comparative role in nutrient cycles of soils.     

苯磺隆和2,4-D对盆栽小麦土壤微生物量碳、氮的影响

通过盆栽小麦试验,研究了除草剂苯磺隆和2,4-D对小麦生长过程中土壤微生物量碳、氮以及碳/氮比(C_mic/N_mic)的影响。结果表明,苯磺隆、2,4-D对土壤微生物量碳、氮的影响主要表现为先抑制后激活,抑制作用随着时间的延长和浓度的增大而增强,与对照相比达极显著差异水平。苯磺隆、2,4-D对微生物量碳的抑制作用第14天和第7天分别达到最大,为54.9%和45.2%;对微生物量氮的抑制作用均为第7天最大,分别为51.0%和 65.4%。2种除草剂处理均在第28天微生物量碳、氮达到最大,为对照的1.09和1.33倍,呈极显著的激活作用,且激活作用随着浓度的增大而增强;对土壤微生物量碳/氮的影响主要呈增加-降低-增加的变化趋势。研究表明苯磺隆、2,4-D对土壤微生物量碳、氮的影响主要与处理的浓度和时间有关,与除草剂的种类无关。     

秸秆施用位置、矿质氮的添加及翻耕措施对只施秸秆的黑土和红壤中微生物生物量碳变化趋势的影响

Quantifying trends in soil microbial biomass carbon (SMBC) under contrasting management conditions is important in understanding the dynamics of soil organic matter (SOM) in soils and in ensuring their sustainable use. Against such a background, a 60-day greenhouse simulation experiment was carried out to study the effects of straw placement, mineral N source, and tillage on SMBC dynamics in two contrasting soils, red soil (Ferrasol) and black soil (Acrisol). The treatments included straw addition + buried (T1); straw addition + mineral N (T2); and straw addition + tillage (T3). Straw was either buried in the soil or placed on the surface. Sampling was done every 15 days. Straw placement, addition of external mineral N sources (Urea, 46% N) and soil type affected SMBC. SMBC levels decreased with exposure durations (15 days, 30 days, 45 days, and 60 days). Rate of SMBC fixation was more in buried straw than in surface placed straw at all sampling dates in both soils. Addition of an external N source significantly increased SMBC level. Soil pH increased in both soil types, with a greater increase in black soil than in red soil. The study could not, however, statistically account for the effect of tillage on SMBC levels because of the limited effect of our tillage method due to the artificial barrier to mechanical interference supplied by the mesh bags, although differences in absolute values were quite evident between treatments T1 and T3.     

氮磷肥对黑土玉米农田生态系统土壤微生物量碳、氮的影响

通过田间氮磷肥配施试验研究了氮磷配施对黑土玉米农田生态系统玉米不同生育时期微生物量碳、氮的影响。微生物量随玉米不同生育期的动态变化表明,氮磷肥对微生物量碳和微生物量氮的动态影响并不同步,微生物量碳和微生物量氮变化最显著的时期均是授粉期,但此时微生物量碳是最低的谷值,而微生物量氮是最高的峰值。不同氮磷配比对微生物量碳影响的回归分析表明,氮肥是影响微生物量碳的主导因素,无论是适量施用还是过量施用都是氮肥对微生物量碳的影响较大。不同氮磷配比对微生物量氮影响的回归分析表明,过量氮肥的施用减少了土壤微生物量氮的含量。磷肥无论高量和低量均能增加微生物量氮的含量,但随着施用量的增加对微生物量氮的正效应减小。氮磷配合施用可增加土壤的微生物量氮,由此可见无论单施氮肥还是单施磷肥,过量施用对微生物量氮的增加都是不利的,只有氮磷配合施用才是增加土壤微生物量氮的有效途径。     

玉米地土壤微生物量碳、氮及微生物熵对不同物料还田的响应

在四川丘陵区紫色土上进行田间试验,以无物料还田为对照,对比分析了蚕豆秸秆、油菜秸秆、猪粪3种物料还田对夏玉米吐丝期和收获期0—20,20—40cm土层土壤有机碳、全氮、微生物量碳氮含量及微生物熵的影响,以期为农业废弃有机物料的综合利用及四川丘陵区土壤质量的提升提供理论参考。结果表明:(1)尽管有机物料还田于0—20cm土层中,0—20,20—40cm土层土壤有机碳(SOC)、全氮(TN)、微生物量碳(SMBC)、微生物量氮(SMBN)含量均受到有机物料的深刻影响。各处理0—20cm土层SOC、TN、SMBC、SMBN含量均显著高于20—40cm土层,且上下2层土壤SOC、TN、SMBC和SMBN含量在生育时期间均表现为吐丝期>收获期。(2)在2个生育时期,3种物料还田均能提高0—20,20—40cm土层SOC、TN、SMBC、SMBN含量。与对照相比,物料还田处理的SOC、TN、SMBC、SMBN含量分别提高2.6%~141.2%,1.9%~33.0%,5.1%~114.7%,41.5%~98.7%,其中收获期各处理0—20,20—40cm土层SOC、SMBC、SMBN均表现为油菜秸秆>蚕豆秸秆>猪粪>对照,TN表现为蚕豆秸秆>猪粪>油菜秸秆>对照。(3)各处理SMBC/SMBN、qMB、SMBN/TN分别为3.74~10.53,0.86%~2.19%,1.01%~3.41%,且物料还田降低SMBC/SMBN,提高土壤qMB和SMBN/TN值。相关分析表明,SMBC、SMBN与SOC、TN之间均存在极显著正相关关系。因此,农业生产中可通过物料还田提供给微生物足够的碳氮营养,提高土壤SMBC、SMBN、SOC、TN含量和qMB值,维持较高的农田生产力,提升土壤质量,但具体施用物料时还需寻求土壤肥力提升、玉米产量增加以及环境效益之间的平衡。     

Effect of cropping systems on phosphatases in soils

Phosphatases are widely distributed in nature and play a major role in phosphorus nutrition of plants. The effects of crop rotations and nitrogen fertilization on the activities of phosphatases (acid phosphatase, alkaline phosphatase, and phosphodiesterase) were studied in soils from two long‐term cropping systems at the Northeast Research Center (NERC) in Nashua and the Clarion Webster Research Center (CWRC) in Kanawha, Iowa, USA. Surface soils (0—15 cm) were taken in 1996 and 1997 from replicated field plots in corn, soybeans, oats, or meadow (alfalfa) that received 0 or 180 kg N ha^—1 before corn. Because of differences in organic C contents among soils of the two sites, the soils from the CWRC sites contained greater enzyme activity values than those from the NERC site. Plots under oats or meadow showed the greatest activity values, whereas those under continuous corn at the CWRC site and soybean at the NERC site showed the least activities. Analysis of variance indicated that the activities of the phosphatases were significantly affected by crop rotation (P < 0.001) in both years at the NERC site but not at the CWRC site. Nitrogen fertilization affected the activity of acid phosphatase in soils from the CWRC site in both years and alkaline phosphatase only in 1997; but it did not affect the activities of the phosphatases in the soils from the NERC site. With the exception of alkaline phosphatase (CWRC) and phosphodiesterase (NERC) in soils sampled in 1997, activities of alkaline phosphatase and phosphodiesterase were significantly correlated with microbial biomass C (C _mic) in soils from both sites and years, with r values ranging from 0.366* to 0.599***. Cropping systems and N fertilization affected the specific activities of phosphomonoesterases, especially acid phosphatase, but not of phosphodiesterase. Regression analysis showed that activities of phosphatases were significantly correlated with organic C contents of soils from the NERC site but not from the CWRC site.