Impact of long-term application of manure,crop residue,and mineral fertilizer on organic carbon pools and crop yields in a Mollisol

Purpose

While the influence of integrated fertility management systems on yield and N cycling in Mollisols is documented, its effect on soil C sequestration remains to be determined. We examined the response of organic C pools and crop yields to 21 years’ organic amendments applied at relatively low rates in a high-C Mollisol to optimize win–win management practices that balance agronomic and environmental interests.

Materials and methods

This study was based on five treatments: CK (unfertilized control), NPK (chemical fertilizer alone), NPKS₁ (NPK plus crop residues), NPKS₂ (NPK plus double amounts of crop residues), and NPKM (NPK plus pig manure). Crop yield was determined by harvesting a defined area. Organic C was quantified by dry combustion. A two-step acid hydrolysis technique was used to quantify hydrolysable and non-hydrolysable C fractions.

Results and discussion

All organic-treated plots produced significantly higher crop yields than the NPK plots, but only the manure treatment resulted in a significant increase in SOC compared with the NPK treatment after 21 years of experiment. It seems that the effects of organic amendments on SOC depend primarily on the type of organic materials when the application rates were relatively low. This indicated that organic amendments offer relatively short-term soil benefits for plant growth. The pig manure builds SOC over the long term, which provides secondary benefits while also sequestering C.

Conclusions

Overall, manure integrated with mineral fertilizer should be recommended to maintain the SOC content and increase crop yield in the Mollisols.     

长期不同施肥对黄泥田土壤酶活性和微生物的影响

以农业部耕地保育福建观测实验站的长期肥料试验为平台,研究了长期不同施肥对黄泥田土壤酶活性和微生物的影响。结果表明:与不施肥(CK)相比,单施NPK(NPK)、NPK配施牛粪(NPKM)及NPK配施秸秆(NPKS)的土壤酶活性均有不同程度的提高,其中NPKM可显著提高转化酶活性,NPKS可显著提高脲酶活性。施肥均不同程度地提高了土壤细菌、真菌及放线菌的数量,尤其是放线菌数量,提高幅度均达到显著性水平;NPKS可显著提高土壤细菌数量,NPKM可显著提高土壤真菌数量。施肥均会对真菌群落产生重要影响;单施化肥对土壤细菌群落的影响不大,增施有机物料会对细菌群落产生明显影响;施用牛粪会对放线菌优势群落产生影响。以上结果表明,有机无机配施更有利于提高土壤酶活性和土壤微生物数量,提升土壤生物肥力。     

长期不同施肥条件下土壤微生物量及 土壤酶活性的季节变化特征

研究长期不同施肥条件下褐潮土微生物量碳（SMBC）、微生物量氮（SMBN）和土壤酶活性随季节的变化特征。结果表明,长期施肥条件下土壤SMBC、SMBN含量及土壤酶活性均表现出一定的季节变化。SMBC、SMBN含量在各施肥处理中的顺序为:化肥与猪厩肥配施处理（NPKM）化肥配施玉米秸秆处理（NPKS）单施化肥处理（NPK）不施肥处理（CK）,各处理之间差异显著(P0.05);施肥还显著提高了土壤脲酶、转化酶、碱性磷酸酶活性,有机无机配施的高于单施化肥的。除过氧化氢酶活性随季节变化显著下降外,SMBC、SMBN、酶活性的值一般在夏季（6月到8月）较高。通过双因素单变量方差分析表明,不同施肥制度与季节变化对SMBC、SMBN与酶活性的影响分别达极显著水平（P0.01）,不同施肥制度的SMBC、SMBN与酶活性的季节波动有极显著不同（P0.01）。     

不同施肥管理对红壤性水稻土有机碳、氮形态的影响

A long-term experiment beginning in 1981 in Jinxian County of Jiangxi Province, subtropical China, was conducted in a paddy field under a double rice cropping system with four different fertilization regimes, including 1) no fertilizer as control (CK), 2) balanced chemical N, P, and K fertilizers (NPK), 3) organic manure using milk vetch and pig manure in the early and late rice growing season, respectively (OM), and 4) balanced chemical fertilizers combined with organic manure (NPKM). Samples (0-17 cm) of the paddy field soil, which was derived from Quaternary red clay, were collected after the late rice harvest in November 2003 for determination of total organic carbon (TOC) and total nitrogen (TN) and fractions of organic C and N. Results showed that TOC and TN in the NPKM and OM treatments were significantly higher than those in other two treatments (CK and NPK). Application of organic manure with or without chemical fertilizers significantly increased the contents of all fractions of organic C and N, whereas chemical fertilizer application only increased the contents of occluded particulate organic C (oPOC) and amino acid N. In addition, application of organic manure significantly enhanced the proportions of free particulate organic carbon (fPOC) and oPOC in total C, and those of amino sugar N and amino acid N (P < 0.01) in total N. In contrast, chemical fertilizer application only increased the proportions of oPOC and amino acid N (P < 0.05). There were no significant differences in either contents or proportions of soil organic C and organic N fractions between the NPKM and OM treatments. These indicated that organic manure application with or without chemical fertilizers played the most significant role in enhancing soil organic C and N quantity and quality in the paddy field studied.     

不同有机肥对黄泥田土壤培肥效果及土壤酶活性的影响

【目的】低产黄泥田在南方稻区广泛分布,其障碍因素是土壤熟化度低,施用有机肥料是改良黄泥田的重要措施。本文通过田间试验研究化肥和不同有机肥对低产黄泥田的培肥效果以及土壤碳、土壤氮、土壤磷转化的相关酶活性的变化规律,为低产黄泥田培肥改良提供理论依据和技术支撑。【方法】试验地位于湖北省京山县,种植模式为双季稻,田间试验中设6个处理, 分别为 （1）不施肥（CK）,（2）单施化肥（NPK）,（3）化肥＋绿肥（NPKG）,（4）化肥＋猪粪（NPKM）,（5）化肥＋秸秆（NPKS）,（6）化肥＋秸秆＋腐熟菌剂（NPKSD）,化肥用量相同,配施有机肥处理施用的有机碳量相当。水稻收获后取耕层土壤样品,测定不同处理土壤养分和土壤酶活性指标,了解土壤养分和土壤酶活性的变化特征;采用典型相关分析方法,分析土壤养分和土壤酶两组变量之间的相关关系,研究不同有机肥对低产黄泥田的培肥效果。【结果】有机肥能够提高土壤碱解氮、速效磷、速效钾含量,明显提高早稻和晚稻的产量。有机肥对土壤酶活性有很大影响,配施有机肥不同程度地提高了-葡萄糖苷酶、 -葡萄糖苷酶、 -纤维二糖苷酶、 -木糖苷酶活性;过氧化物酶和脲酶没有明显差异;磷酸酶、乙酰氨基葡萄糖苷酶、酚氧化酶活性有所降低。土壤酶活性是评价施肥对土壤肥力影响的重要生物指标,土壤养分和土壤酶活性典型相关分析结果显示,二者显著相关,可以用于评估黄泥田土壤肥力变化的酶主要有-葡萄糖苷酶、 -木糖苷酶、 -葡萄糖苷酶、 -纤维二糖苷酶。典型变量排序结果表明,有机肥的培肥效果秸秆＞猪粪＞绿肥。【结论】低产黄泥田增施有机肥可以显著提高水稻产量和土壤速效养分含量,施用不同有机肥9种土壤酶活性响应不同,其中-葡萄糖苷酶、-木糖苷酶、-葡萄糖苷酶、-纤维二糖苷酶活性可以用于表征低产黄泥田的肥力变化,不同有机肥的培肥效果为秸秆＞猪粪＞绿肥。     

灰漠土小麦-玉米-棉花轮作体系钾平衡与钾肥利用率

研究了干旱区灰漠土农田典型作物长期定位方式下不同施肥处理对钾平衡及钾形态和利用率的影响。实验包括9个处理,分别为不施肥(CK)、氮磷钾不均衡配施(N、NP、NK和PK)以及均衡施肥与秸秆或有机肥配施(NPK、NPKS、NPKM和1.5 NPKM)。结果表明,均衡施肥的产量显著高于不均衡施肥处理(NP除外)(p0.05)。其中NP处理的产量与其他均衡施肥产量并无明显差异(p0.05),说明钾不是灰漠土农田亏缺养分。钾平衡法发现,均衡施肥中NPKS表现出钾的盈余,而其余均衡施肥处理表现出钾的亏缺,24年亏缺量达到268至2 966 kg hm-2。所有施肥处理中,NPKM和1.5NPKM拥有最高的钾表观利用率,分别达到81.2%和38.9%,显著高于其他处理(p0.05),说明配施有机肥可以显著提高灰漠土钾肥利用率。长期定位试验后,不同处理的钾素形态变化显著,尤其有机肥添加处理的非交换性钾、非特殊吸附性钾、水溶性钾和交换性钾显著高于其他处理(p0.05),进一步说明配施有机肥或秸秆维持灰漠土农田钾素肥力方面的重要性。总而言之,当前灰漠土农田常规施肥方式下的钾亏缺正在逐步加大,补充更多的钾肥以及配合使用有机肥或秸秆应当被重视。     

Continuous manuring combined with chemical fertilizer affects soil microbial residues in a Mollisol

In this study, the influence of 10 years’ continuous application of organic manure at various rates combined with chemical fertilizer on microbial residues was evaluated in a highly fertile temperate soil. The presence and origin of microbial residues were indicated by amino sugar analysis. The treatments were: (1) CK, unfertilized control; (2) OM₀, only chemical fertilizer, no manure added; (3) OM₁, organic manure added at 7.5 Mg?ha^?1?year^?1 plus chemical fertilizer; (4) OM₂, organic manure added at 15 Mg?ha^?1?year^?1 plus chemical fertilizer; and (5) OM₃, organic manure added at 22.5 Mg?ha^?1?year^?1 plus chemical fertilizer. Fertilization significantly increased the total amino sugar concentrations, especially in the plots with higher manure addition rates (OM₂ and OM₃ plots, P?<?0.05). This suggests a positive effect of organic manure combined with chemical fertilizer on the accumulation of microbial residues in soil. However, the highest manure rate (OM₃) did not lead to further increase in the total amino sugar pool as compared with the moderate manure rate (OM₂). This suggests manure addition “saturates” in its effect on microbial residue build-up. The different patterns of individual amino sugars suggest a change in the quality of microbial-derived soil organic matter after 10 years.     

Impact of long-term application of fertilizer, manure and lime under intensive cropping on physical properties and organic carbon content of an Alfisol

Intensive cropping with conventional tillage results in a decline of soil organic carbon (SOC) with consequent deterioration of soil physical properties. Some studies indicate that this decline in SOC can be arrested by way of organic manure application and improved nutrient management practices. This study was conducted to find out the long-term effects of inorganic fertilizer, manure and lime application on organic carbon content and physical properties of an acidic Alfisol (Typic Haplustalf) under an annual soybean-wheat crop rotation. Six treatments namely, control (CON), nitrogen fertilization (NIT), nitrogen and phosphorus (NP), nitrogen, phosphorus and potassium (NPK), NPK plus manure (NPKM) and NPK plus lime (NPKL) from a long-term fertilizer experiment continuing at Ranchi, India, were chosen for this study. Soil samples were collected from the selected treatments after 29 crop cycles and analyzed for physical and chemical properties. The results indicated that SOC content in all the treatments decreased from initial levels, but the decrease was considerably less in NPKM (8.7%) and NPKL (10.9%) treatments than that in NIT (28.3%) treatment. The SOC at 0-15 and 15-30 cm depth was lowest in NIT and CON. The NPKM, NPKL and NPK treatments up to 30 cm soil depth recorded significantly higher SOC than NIT and CON. Application of balanced fertilizer along with manure (NPKM) or lime (NPKL) improved soil aggregation, soil water retention, microporosity and available water capacity and reduced bulk density of the soil in 0-30 cm depth over CON. In contrast, soil aggregate stability, microporosity and available water capacity were significantly lower in the NIT plots than that in CON. The study thus suggests that soil management practices in acidic Alfisols should include integrated use of mineral fertilizer and organic manure or lime to maintain the organic carbon status and physical environment of soil.     

西湖平原区连续13年定位施肥对麦、稻产量及土壤肥力的影响

以浙江省水网平原水稻主产区土壤为对象,通过定位试验,研究了连续13年的不同施肥处理对麦稻产量、土壤养分状况和物理性状的影响。结果表明,化肥配施有机肥可显著提高麦、稻产量; 不同施肥处理的长期定位试验土壤有机质含量和全氮均呈上升趋势,增幅依次为: 栏肥+NPK秸秆+NPKNPK秸秆栏肥CK处理; 土壤碱解氮和速效磷也呈增加趋势,以栏肥+NPK处理的增幅最为明显。土壤物理性状的分析表明,长期施肥均能明显增加土壤水稳性团粒含量和土壤孔隙度。经土壤养分平衡分析,栏肥+NPK、秸秆+NPK和NPK处理的氮和磷呈现盈余,秸秆和CK处理氮和磷亏缺; 栏肥+NPK和秸秆+NPK处理钾基本平衡,NPK、秸秆、栏肥和CK处理钾严重亏缺。长期定位试验进一步证明有机肥与氮、磷、钾化肥长期配合施用可实现当地农作物持续稳产,农田施肥管理要注意适当减少氮、磷投入,增加钾肥施用量,保持农田土壤养分平衡。     

长期施氮、磷、钾化肥对玉米产量及土壤肥力的影响

以1990年建立的国家褐潮土土壤肥力与肥料效益长期监测基地(北京昌平站)的长期肥料定位试验为研究平台,研究了不同施肥制度对玉米产量和土壤肥力的影响。结果表明,长期均衡地施NPK肥或NPK与有机肥配施,可以显著提高玉米产量和土壤有机质、全氮、全磷、速效氮、速效磷、速效钾等肥力指标,并能提高土壤微量元素的含量;而不均衡施肥(N、NK、NP、PK)导致相应的营养元素的耗竭。相关分析表明,在褐潮土上增施磷肥和有机肥对提高玉米产量具有重要的作用。     

长期施肥下新疆灰漠土有机碳及作物产量演变

为明确长期不同施肥下新疆灰漠土有机碳和作物产量演变特征,依托始于1990年的灰漠土肥力长期定位监测试验,选择对照(CK,不施肥)、施氮磷肥(NP)、氮磷钾平衡施肥(NPK)、氮磷钾配合常量有机肥(NPKM)、氮磷钾配合高量有机肥(h NPKM,有机肥施用量为NPKM的2倍)、氮磷钾配合秸秆还田(NPKS)6个处理,分析不同处理下土壤有机碳和小麦、玉米产量演变特征,探讨碳投入及有机碳与作物产量的关系。结果表明:1)长期耗竭种植(CK)、连续施用NP或NPK肥,灰漠土有机碳含量持续下降,年均下降速率分别为0.094 g·kg~(-1)、0.043 g·kg~(-1)和0.053 g·kg~(-1),表明施化肥(NP、NPK)不能维持土壤有机碳含量,不利于土壤肥力的保持。NPKM和h NPKM处理,土壤有机碳显著增加,年均增加0.360 g·kg~(-1)和0.575 g·kg~(-1),增施有机肥是快速提高灰漠土肥力的重要措施。秸秆还田处理(NKPS),土壤有机碳年均增幅0.006 g·kg~(-1),与NPK处理对比,秸秆还田虽没有大幅度提高土壤有机碳,但维持了土壤肥力。2)较CK,长期化肥有机肥配施(NPKM、h NPKM)显著增加了作物产量(P0.05)。与NP和NPK比较,长期化肥有机肥配施显著提高了小麦产量(P0.05),但玉米产量与施化肥处理差异不显著(P0.05),玉米产量以平衡施肥(NPK)的增幅最高,达到220 kg·hm~(-2)·a~(-1)。小麦的产量变异系数(29.1%~43.9%)高于玉米产量变异(19.0%~32.7%)。化肥配合秸秆还田(NPKS)处理的小麦增产幅度与高量施用有机肥(h NPKM)处理接近,喻示了秸秆还田对作物增产的作用不可忽视。3)碳投入与土壤有机碳和小麦、玉米产量有显著线性正相关(P0.05)。基于以上分析,在干旱区灰漠土增加土壤碳投入(有机肥或秸秆)仍然是最基本的土壤培肥措施。     

不同施肥模式对南方黄泥田耕层有机碳固存及生产力的影响

【目的】探讨南方丘陵黄泥田不同施肥对耕层土壤有机碳固存及生产力的影响,促进区域农田固碳减排和作物高产。【方法】基于32年的长期定位试验,研究不施肥(CK)、单施化肥(NPK)、化肥+牛粪(NPKM)、化肥+全部稻草还田(NPKS)处理下,历年水稻产量、代表性年份耕层土壤有机碳含量及固碳速率的变化。【结果】NPK、NPKM、NPKS处理下水稻历年平均产量分别较CK高67.1%、88.1%和84.2%,差异显著,且NPKM、NPKS处理与NPK处理间亦具有显著差异。NPK、NPKM与NPKS处理耕层土壤有机碳历年平均含量比CK高8.9%~36.8%其中NPKM最高且亦显著高于NPKS与NPK处理。与初始土壤相比各处理有机碳含量增加1.84~5.26g/kg。以每10年为评价周期,NPKM、NPKS处理的固碳速率与CK及NPK差异均显著,其中双季稻年份NPKM与NPKS处理固碳速率分别是CK的2.38倍和1.98倍,是NPK处理的1.59倍与1.32倍但NPK处理与CK间差异不显著。稻田系统年均有机碳输入与有机碳固存间存在极显著幂函数关系,施肥土壤有机碳含量变化与籽粒产量变化间亦呈极显著正相关。【结论】南方黄泥田化肥配施有机肥或配合秸秆还田较单施化肥稳步提升水稻产量。长期不施肥土壤有机碳仍可维持低幅度增长,随着土壤有机碳含量升高,固碳效率逐步降低。化肥配施有机肥或配合秸秆还田较单施化肥明显提高了土壤的固碳速率二者均是提高黄泥田生产力与固碳能力的双赢措施。     

Soil organic carbon sequestration under different fertilizer regimes in north and northeast China: RothC simulation

Soil organic carbon (SOC) modelling is a useful approach to assess the impact of nutrient management on carbon sequestration. RothC was parameterized and evaluated with two long‐term experiments comparing different fertilizer treatments in north (Zhengzhou) and northeast (Gongzhuling) China. Four nutrient application treatments were used: no fertilizer (Control), mineral nitrogen–phosphorus–potassium fertilizers (NPK), NPK mineral fertilizer plus manure (NPKM), and NPK mineral fertilizer plus straw return (NPKS). The comparison between simulated and observed data showed that the model can adequately simulate SOC contents in the Control, NPK and NPKM treatments but overestimated in the NPKS treatment at both sites. By changing the value of decomposable plant material:resistant plant material (DPM:RPM) ratio from the default value to 3.35 for the NPKS treatment at the Zhengzhou site, dynamics of simulated SOC agreed with measured values. A pseudo‐parameter, straw retention factor was introduced to adjust the amount of straw incorporated into soils. Using the inverse simulation method and the modified value of the ratio, the best‐fitted value was 0.24 for the NPKS treatment at the Gongzhuling site. This result indicated that retaining straw on the soil surface makes less contribution to carbon sequestration than if it is incorporated. With this modification for straw, the model produced reasonable predictions for the two sites. The model was run for another 30 years with the modified parameter values and current average climatic conditions for different fertilizer treatments at both sites. The results suggested that the NPK application plus the addition of manure or straw would be better management practices for carbon sequestration.     

长期施用不同有机肥对甘薯产量和土壤生物性状的影响

以花生—甘薯轮作的长期定位试验为研究对象,研究不同(类)有机肥对甘薯产量、土壤微生物丰度和酶活性的影响,为选取合适的有机肥在提高作物产量和改善土壤生物性状方面提供依据。共选取5个施肥处理:(1)CK,空白对照;(2)NPK,单施化肥;(3)NPK+SR,化肥+稻草;(4)NPK+M,化肥+商品有机肥;(5)NPK+P,化肥+猪粪。结果表明:与CK相比,NPK、NPK+SR、NPK+M和NPK+P处理均显著增加鲜薯产量和地上部生物量(P<0.05),其中NPK+P处理效果最好。与CK比较,NPK处理显著降低土壤细菌、真菌、固氮菌和活化有机磷微生物的丰度(P<0.05),而NPK+SR、NPK+M和NPK+P处理在不同程度上缓解了NPK处理对土壤微生物丰度的抑制作用。土壤酶的加权平均值(GMea)在一定程度上可用来评价土壤酶的总体活性。与CK相比,NPK、NPK+SR和NPK+M处理的土壤酶活性显著降低(P<0.05),而NPK+P处理的土壤酶活性有所提高;对于土壤单一酶活性,NPK+P处理与CK比较显著降低土壤脲酶活性(P<0.05),但显著提高酸性磷酸酶、碱性磷酸酶和过氧化氢酶活性。此外,主成分和相关性分析表明,土壤养分和土壤有机碳与鲜薯产量和地上部生物量显著正相关,土壤pH是驱动土壤微生物丰度和土壤酶活性变化的主要因素。因此,长期有机无机肥配施通过提高土壤养分、有机碳含量以及调节土壤pH变化在提高甘薯产量和改善土壤生物性状方面取得良好效果。总体来说,化肥配施猪粪在培肥地力和增产增收方面效果最佳。     

Microbial residues were increased by film mulching with manure amendment in a semiarid agroecosystem

Amino sugars, as a kind of microbial residue, are strongly associated with cycling of microbial-derived soil organic matter. However, responses of amino sugars to agricultural practices on the Loess Plateau in North-western China are poorly known. The objective was to evaluate effects of film mulching (no film mulching + NPK fertilizers, CK; film mulching + NPK fertilizers, PF; film mulching + NPK fertilizers + cow manure, FM) on accumulations of amino sugars in this region. FM significantly increased total amino sugar by 190.46 mg kg^?1 in 0–10 cm layer and 214.66 mg kg^?1 in 10–20 cm layer relative to CK, but PF significantly decreased it by 139.28 mg kg^?1 in 0–10 cm layer. Ratios of glucosamine to muramic acid were markedly decreased by 2.50 in 0–10 cm layer and 2.28 in 10–20 cm layer in FM than CK, suggesting a tendency of microbial residues pool shift towards bacterial residues in this agroecosystem. These results indicated film mulching alone was not benefitial to accumulation of amino sugar while organic manure contributed to the build-up of amino sugar partly due to manure contained microbial residues. The different patterns of amino sugars suggested significant changes in the quality of microbial-derived organic matter.     

长期不同施肥对南方黄泥田水稻子粒与土壤锌、 硼、 铜、 铁、 锰含量的影响

在福建黄泥田长期定位施肥试验的第26年,研究了不同施肥模式对水稻子粒与土壤微量元素含量的影响。结果表明,与不施肥（CK）相比,化肥+牛粪（NPKM）、 化肥+秸秆还田（NPKS）及单施化肥（NPK）处理的水稻子粒Zn、 B、 Cu含量均有不同程度的提高,并尤以NPKM处理最为明显,三种微量元素含量分别提高14.3%、 25.1%、 465.2%,均达差异显著水平。NPKM与NPKS处理还不同程度地提高了子粒Mn含量,但各施肥处理的子粒Fe含量均显著降低。各施肥处理尤其是NPKM与NPKS均显著提高了子粒微量元素吸收量。NPK处理的土壤有效B、 Fe、 Zn、 Cu含量与CK相比均呈下降趋势,且有效Zn、 Mn含量较试验前土壤分别降低了36.4%与24.6%,而NPKM与NPKS处理缓解了下降趋势,且NPKM处理的土壤有效Zn、 B、 Mn含量分别较CK提高46.6%、 52.0%、 43.0%,均达差异显著水平。土壤有机质与子粒B、 Cu、 Zn含量呈显著正相关,子粒必需氨基酸、 粗蛋白与子粒Zn含量呈显著正相关。以上结果说明,长期化肥配施牛粪或秸秆还田有利于提高水稻子粒Zn、 B、 Cu等微量元素含量和产量,改善子粒营养品质,一定程度上又可缓解土壤有效微量元素含量的下降,是适合南方黄泥田的施肥模式。     

长期有机无机肥配施降低黄淮海区域小麦?大豆复种系统净温室效应

  【目的】  小麦?大豆系统是黄淮海区域重要的禾豆复种系统，综合评价该系统的净碳排放对于我国农田固碳减排具有重要意义。借助30年的长期定位试验，综合评价不同施肥处理下小麦?大豆复种系统的产量和净碳排放，旨在为该系统丰产低碳排放的施肥制度创新提供理论依据。  【方法】  试验包括单施牛粪 (M)、氮磷钾平衡施肥 (NPK)、氮磷钾加牛粪 (NPKM)、氮磷加秸秆 (NPS)、氮磷钾加饼肥 (NPKC)、氮磷钾加牛粪及饼肥 (NPKMC) 以及不施肥对照 (CK)，共7个处理。综合分析了各处理田间直接温室气体排放 (N₂O和CH₄)、农田投入导致的间接碳排放与土壤有机碳固定，估算了单施牛粪、单施化肥以及化肥与不同有机物料配施的净碳排放，同时将碳排放与作物产量和土壤有机质相结合，综合评价了不同施肥措施下的净温室效应。  【结果】  小麦?大豆复种系统中，小麦季施肥对大豆产量有显著后效，与单施NPK相比，NPKM、NPKC和NPKMC处理分别使大豆产量提高了31.0%、16.8%和24.0%，而M和NPS处理不利于大豆、小麦产量的提高。与NPK处理相比，M、NPKM、NPKMC处理的农田直接温室气体排放分别增加了49.4%、17.7%和12.4%，土壤有机碳年固定量分别显著提高了282.2%、137.3%和169.1%。M及NPKM处理的间接碳排放与NPK处理没有明显差异，而其他施肥处理的间接碳排放低于NPK处理。在各施肥处理中，由肥料投入导致的碳排放占总间接碳排放的比例最大，其次是灌溉用电和机械用柴油导致的碳排放。对净碳排放的估算结果表明，M处理的净碳排放为负值 (表现为碳汇)，而其他处理下小麦–大豆复种系统均表现为碳源，NPK与有机物料配施的处理净碳排放显著低于NPK处理。此外，与NPK处理相比，NPK与有机物料配施使碳排放强度显著降低了36.5%～113.2%，使单位土壤有机质提升的温室气体排放 (δGHG/δSOM) 降低了69.4%～93.2%。  【结论】  黄淮海区域小麦?大豆复种系统中，氮磷钾配施有机肥 (牛粪或饼肥) 可在保证小麦和大豆产量的同时，降低小麦?大豆复种系统的净温室效应。     

Phosphorus availability and rice grain yield in a paddy soil in response to long-term fertilization

Rice (Oryza sativa L.) is one of the most important crops in the world, and its production is limited by soil phosphorus (P) deficiencies in many parts of the world. Impacts of long-term fertilization regimes on rice productivity and soil P availability is largely unknown. A long-term (26-year) field experiment in a paddy soil of southeastern China was carried out to study the response of rice grain yield and soil P pools to different fertilization regimes including control without fertilization (CK), nitrogen, P, and potassium (NPK) fertilizer (NPK), NPK fertilizer plus cattle manure (NPKM), and NPK fertilizer plus rice straw (NPKS). Application of fertilizers (NPK, NPKM, and NPKS) increased rice grain yield compared with the CK treatment (on average, by 75%, 97%, and 92%, respectively). Soil P was predominately present in the organic form (51–75% of total P) across different treatments. Most soil inorganic P fractions decreased with time due to continuous depletion by rice plants in the nonfertilized treatment (CK), while they generally increased with time in the fertilizer treatments (NPK, NPKM, and NPKS) due to continued supply of P to soil. On the other hand, soil organic P fractions increased continuously with time regardless of treatment, probably due to the retention of stubble and biological immobilization of inorganic P. Positive relationships between the rice grain yield and most inorganic P fractions in the CK treatment indicated the P limitation for rice production due to no P inputs and long-term conversion of inorganic P into organic P.     

应用DNDC模型分析东北黑土有机碳演变规律及其与作物产量之间的协同关系

【目的】探索长期不同施肥方式下土壤有机碳的动态变化及其与作物产量之间的耦合关系,以期为东北地区黑土耕地资源的持续利用与管理提供科学依据。 【方法】基于黑土区国家土壤肥力与肥料效益监测网站公主岭监测基地的23年长期定位试验数据,选取不施肥（CK）、单施氮磷钾肥（NPK）、无机肥配施低量有机肥（NPKM1）、1.5倍的无机肥配施低量有机肥[1.5（NPK）M1]、无机肥配施高量有机肥（NPKM2）和无机肥配施秸秆（NPKS）6个处理进行土壤有机碳和产量的分析,将数据用于DNDC模型验证,并对6种施肥处理在未来气候下（40 a）黑土有机碳的演变进行模拟。 【结果】试验监测结果表明:从1990~2012年的土壤有机碳数据分析得出,长期不施肥土壤有机碳从12.49 g/kg以年均0.69%的速率下降,有机无机配施可以提升土壤有机碳含量。DNDC验证结果如下:DNDC验证土壤有机碳时各处理的相对均方根误差（RMSE）为14.98%~37.91%,验证作物产量时各处理的RMSE为8.28%~11.19%,说明模型能够基本反映长期不同施肥下的作物产量和土壤有机碳的变化。未来气候下的模拟结果表明:CK和NPK处理土壤有机碳在未来40年里分别下降16.67%和11.21%。而3个化肥有机肥配施处理在未来40年呈稳定增长态势,NPKM1、1.5（NPK）M1和NPKM2处理的土壤有机碳将分别增加13.65%、15.74%和15.84%,以1.5（NPK）M1增势最为显著。NPKS处理的有机碳相对初始略有增加。当施氮量从160 kg/hm2增至320 kg/hm2时,土壤有机碳每增加1.00 g/kg,作物产量的增加量从44.48 kg/hm2下降至15.95 kg/hm2。 【结论】从长期实测数据的分析和DNDC模型模拟得出,实施秸秆还田和有机肥配施无机肥能有效持续增加SOC含量,并能获得较高的作物产量。在施氮量160~320 kg/hm2水平下,作物产量随着土壤有机碳含量的增加而升高,且土壤有机碳含量对产量的提升幅度随着施氮量的升高而降低。     

长期不同施肥模式下南方典型农田磷肥回收率变化

【目的】 通过比较南方典型农田不同土壤类型、不同施肥模式下的土壤供磷能力、磷肥回收率,揭示长期施肥下磷肥回收率时空变化特征,为区域内磷肥的合理施用提供科学依据。 【方法】 基于重庆北碚紫色土 (始于1991)、湖南望城 (始于1981) 和江西进贤 (始于1981) 红壤性水稻土长期施肥定位试验。选取不施肥 (CK)、单施稻草、厩肥 (M)、施化学氮钾肥 (NK)、施化学氮钾肥+猪粪 (NKM)、施化学氮磷肥 (NP)、施化学氮磷钾肥 (NPK)、施氮磷钾肥+厩肥、猪粪 (NPKM) 或稻草 (NPKS) 等不同施肥处理,分析长期不同施肥下作物吸磷量、磷肥回收率和磷肥累积回收率的动态变化,探讨不同施肥下作物磷肥回收率的变化特征。 【结果】 长期不施磷肥,土壤自然供磷量显著下降,北碚紫色土 (21年)、望城 (23年) 和进贤 (27年) 红壤性水稻土的年下降速率分别为0.60、0.48和0.63 kg/hm2。各试验点不同处理作物历年平均吸磷量的大小顺序为NPK、NPKS和NPKM > NP、NKM > CK或NK ( P < 0.05)。NPK配施猪粪,与配施厩肥或秸秆配施相比较,其作物吸磷量更高。3个试验点磷肥回收率随着施肥年限增加而提高。NPK处理磷肥回收率每年增加0.15%～1.94%, NPKM和NPKS处理磷肥回收率每年增加0.07%～1.60%。NPK处理磷肥累积回收率在37.8%～61.5%之间,NPKM和NPKS处理,其磷肥累积回收率较NPK处理降低了3.0%～34.3%。 【结论】 土壤的磷素自然供给量随作物种植年限增加而显著下降。磷肥的施用能够显著提高作物的吸磷量,NPK平衡施用的吸磷量显著高于化肥偏施;氮肥投入量每增加100 kg/hm2,作物吸磷量增加5 kg/hm2。各试验点磷肥回收率随施肥年限的增加而提高。NPK配施有机肥相比较NPK,降低了磷肥的累积回收率。磷肥施用量每增加 P 10 kg /hm2,磷肥回收率下降约0.9%。NPK与猪粪配合施用的情况下,可以考虑通过适当提高化学氮肥用量、减少化学磷肥投入的措施,从而提高磷肥回收率。