Soil‐quality‐index model for assessing the impact of groundwater on soil in an intensively farmed coastal area of E China

Soil quality is important in measuring sustainable land‐use and soil‐management practices. It is usually assessed by evaluating important physical, chemical, and biological soil properties. For this study, a site‐specific 22 variables representing pertinent soil (0–10 cm) and groundwater properties were selected as potential soil‐quality indicators in a coastal salt‐affected farmland of E China. To investigate the role of groundwater in soil‐quality assessment, we designed two sets of minimum data sets (MDSs). Minimum data set 1 (MDS1) had inputs of the 19 soil chemical and physical properties whereas MDS2 was based on the 22 soil and groundwater properties. Using principal‐component analysis, discriminant analysis, and soil‐quality‐index (SQI) model, we demonstrated the procedures of MDS selection, indicator normalization, and integration of MDS into SQI value for soils used for the two cropping systems. Results indicated selection of SOCD, AK, and ρ_b as MDS1 indicators but MDS2 indicators included SOM, SOCD, Cl, Na, WT_g, and EC_g. These were found to be the most effective discriminators between the two cropping systems. Available K (AK) made greatest contribution to SQI using MDS1 indicators, however, WT_g, EC_g, and Cl were the greatest contributors to the SQI for MDS2. Contribution of SOCD to SQI was severely inhibited in cotton–barley rotation system while EC_g and WT_g contributions to SQI were inhibited in rice–rape rotation system. In general, cotton–barley rotation system had a better soil quality over rice–rape rotation system as the former had higher SQI values than the latter for both MDSs. Crop parameters did also exhibit significant relationship with the SQI values using MDS2 but it was not significant for MDS1. Our results suggest that in addition to soil chemical, physical, and biological indicators, groundwater properties particularly the WT_g and EC_g are also important for assessing soil quality in an intensively farmed coastal area.     

Indexing Soil Quality under Long-Term Maize-Wheat Cropping System in an Acidic Alfisol

A study was undertaken to identify suitable indicators of soil quality from a long-term fertilizer experiment conducted since 1972, which was laid out in a randomized block design with eleven treatments replicated three times. Surface (0–0.15 m) soil samples were collected after harvest of wheat crop during 2010–11 and were analyzed for physical, chemical, and biological properties. Sustainable yield index (SYI) was calculated based on long-term yield data. Highest and lowest overall SYI values were found in balanced fertilization along with manures and urea-only treatments, respectively. Saturated hydraulic conductivity, pH, labile carbon, available phosphorus (P) and potassium (K), pentetate zinc trisodium (DTPA Zn), and nitrogen mineralization were most important minimum dataset (MDS) indicators. The greatest soil quality index (SQI) value was found in balanced fertilization along with manures followed by balanced fertilization along with lime; and the urea-only treatment was the lowest. Balanced fertilization along with manures showed positive change in soil quality and maintained sustainability of productivity.     

Long‐term effects of fertilizer and manure applications on soil quality and yields in a sub‐humid tropical rice‐rice system

Widespread yield stagnation and productivity declines in the rice–rice cropping system have been reported and many of the associated issues are related to soil quality. A long‐term experimental study was initiated in 1969 to assess the impact of continuous cultivation of rice as a single crop grown in wet as well as dry seasons using varying levels of chemical fertilizer and manure applications on soil quality indicators (physical, chemical and biological), a sustainable yield index (SYI) and a soil quality index (SQI). The treatments comprised chemical fertilizers and farmyard manure (FYM) either alone or in combination viz. control, N, NP, NK, NPK, FYM, N+FYM, NP+FYM, NK+FYM and NPK+FYM, laid out in a randomized complete block design with three replications. Soil samples were collected after the wet season rice harvest in 2010 and were analysed for physical, chemical and biological indicators of soil quality. A SYI based on long‐term yield data and SQI using principal component analysis (PCA) and nonlinear scoring functions were calculated. Application of NPK fertilizers in combination with FYM significantly increased the average grain yield of rice in both wet and dry seasons and enhanced the sustainability of the system compared to the control and plots in receipt of fertilizers. The SYI for the control was higher in the wet season than in the dry one, whereas the reverse was true for NPK+FYM treatment. The value of the dimensionless SQI varied from 1.46 in the control plot to 3.78 in the NPK+FYM one. A greater SYI and SQI in the NPK+FYM treatment demonstrated the importance of using a chemical fertilizer in combination with FYM. For the six soil quality indicators selected as a minimum data set (MDS), the contribution of DTPA‐Zn, available‐N and soil organic carbon to the SQI was substantial ranging from 59.4 to 85.7 per cent in NPK+FYM and control plots, respectively. Thus, these soil parameters could be used to monitor soil quality in a subhumid tropical rice–rice system.     

The effects of compost in a rice–wheat cropping system on aggregate size,carbon and nitrogen content of the size–density fraction and chemical composition of soil organic matter,as shown by 13C CP NMR spectroscopy

We investigated whether the long‐term application of compost from agricultural waste improved soil physical structure, fertility and soil organic matter (SOM) storage. In 2006, we began a long‐term field experiment based on a rice–wheat rotation cropping system, having a control without fertilizer (NF) and three treatments: chemical fertilizers (CF), pig manure compost (PMC) and a prilled mixture of PMC and inorganic fertilizers (OICF). Following the harvest of wheat in 2010, the mean‐weight diameter (MWD) of water‐stable aggregates and the concentration of C and N in bulk soil (0–20 cm; <2 mm fraction) were significantly greater (P < 0.05) in PMC and NF plots than in CF or OICF plots. Pig manure compost significantly increased the proportion of >5‐mm aggregates, whereas CF significantly increased the proportion of 0.45‐ to 1‐mm aggregates. The C and N contents of all density fractions were greater in PMC than in other treatments with levels decreasing in the following order: free particulate organic matter (fPOM) >occluded particulate organic matter (oPOM) > mineral‐combined SOM (mineral–SOM). Solid‐state ¹³C CPMAS NMR spectra showed that alkyl C/O‐alkyl C ratios and aromatic component levels of SOM were smaller in PMC and OICF plots than in CF plots, suggesting that SOM in PMC and OICF plots was less degraded than that in CF plots. Nevertheless, yields of wheat in PMC and NF plots were smaller than those in CF and OICF plots, indicating that conditions for producing large grain yields did not maintain soil fertility.     

洱海流域减氮施肥条件下水稻产量和土壤剖面氮磷变化特征

[目的]研究实现水稻稳产和土壤氮磷淋失低风险的肥料管理措施,以减少农田养分进入流域水域的风险,并提高农业生产的效益.[方法]田间试验在云南大理国家农田生态系统野外观测研究站进行,种植制度为水稻–大蒜–水稻–蚕豆轮作,试验连续进行了两年.设置8个水稻施肥处理:不施肥(CK);常规施肥(CF);减施20％常规肥(T1);等...     

Long‐term fertilization impacts on corn yields and soil organic matter on a clay‐loam soil in Northeast China

A long‐term fertilization experiment with monoculture corn (Zea mays L.) was established in 1980 on a clay‐loam soil (Black Soil in Chinese Soil Classification and Typic Halpudoll in USDA Soil Taxonomy) at Gongzhuling, Jilin Province, China. The experiment aimed to study the sustainability of grain‐corn production on this soil type with eight different nitrogen (N)‐, phosphorus (P)‐, and potassium (K)–mineral fertilizer combinations and three levels (0, 30, and 60 Mg ha^–1 y^–1) of farmyard manure (FYM). On average, FYM additions produced higher grain yields (7.78 and 8.03 Mg ha^–1) compared to the FYM0 (no farmyard application) treatments (5.67 Mg ha^–1). The application of N fertilizer (solely or in various combinations with P and K) in the FYM0 treatment resulted in substantial grain‐yield increases compared to the FYM0 control treatment (3.56 Mg ha^–1). However, the use of NP or NK did not yield in any significant additional effect on the corn yield compared to the use of N alone. The treatments involving P, K, and PK fertilizers resulted in an average 24% increase in yield over the FYM0 control. Over all FYM treatments, the effect of fertilization on corn yield was NPK > NP = NK = N > PK = P > K = control. Farmyard‐manure additions for 25 y increased soil organic‐matter (SOM) content by 3.8 g kg^–1 (13.6%) in the FYM1 treatments and by 7.8 g kg^–1 (27.8%) in the FYM2 treatments, compared to a 3.2 g kg^–1 decrease (11.4%) in the FYM0 treatments. Overall, the results suggest that mineral fertilizers can maintain high yields, but a combination of mineral fertilizers plus farmyard manure are needed to enhance soil organic‐matter levels in this soil type.     

Long‐term effects of manure and fertilization on soil organic matter and quality parameters of a calcareous soil in NW China

Long‐term applications of inorganic fertilizers and farmyard manure influence organic matter as well as other soil‐quality parameters, but the magnitude of change depends on soil‐climatic conditions. Effects of 22 annual applications (1982–2003) of N, P, and K inorganic fertilizers and farmyard manure (M) on total organic carbon (TOC) and nitrogen (TON), light‐fraction organic C (LFOC) and N (LFON), microbial‐biomass C (MB‐C) and N (MB‐N), total and extractable P, total and exchangeable K, and pH in 0–20 cm soil, nitrate‐N (NO ‐N) in 0–210 cm soil, and N, P, and K balance sheets were determined using a field experiment established in 1982 on a calcareous desert soil (Orthic Anthrosol) at Zhangye, Gansu, China. A rotation of irrigated wheat (Triticum aestivum L.)‐wheat‐corn (Zea mays L.) was used to compare the control, N, NP, NPK, M, MN, MNP, and MNPK treatments. Annual additions of inorganic fertilizers for 22 y increased mass of LFON, MB‐N, total P, extractable P, and exchangeable K in topsoil. This effect was generally enhanced with manure application. Application of manure also increased mass of TOC and MB‐C in soil, and tended to increase LFOC, TON, and MB‐N. There was no noticeable effect of fertilizer and manure application on soil pH. There was a close relationship between some soil‐quality parameters and the amount of C or N in straw that was returned to the soil. The N fertilizer alone resulted in accumulation of large amounts of NO ‐N at the 0–210 cm soil depth, accounting for 6% of the total applied N, but had the lowest recovery of applied N in the crop (34%). Manure alone resulted in higher NO ‐N in the soil profile compared with the control, and the MN treatment had the highest amount of NO ‐N in the soil profile. Application of N in combination with P and/or K fertilizers in both manured and unmanured treatments usually reduced NO ‐N accumulation in the soil profile compared with N alone and increased the N recovery in the crop as much as 66%. The N that was unaccounted for, as a percentage of applied N, was highest in the N‐alone treatment (60%) and lowest in the NPK treatment (30%). In the manure + chemical fertilizer treatments, the unaccounted N ranged from 35% to 43%. Long‐term P fertilization resulted in accumulation of extractable P in the surface soil. Compared to the control, the amount of P in soil‐plant system was surplus in plots that received P as fertilizer and/or manure, and the unaccounted P as percentage of applied P ranged from 64% to 80%. In the no‐manure plots, the unaccounted P decreased from 72% in NP to 64% in NPK treatment from increased P uptake due to balanced fertilization. Compared to the control, the amount of K in soil‐plant system was deficit in NPK treatment, i.e., the recovery of K in soil + plant was more than the amount of applied K. In manure treatments, the recovery of applied K in crop increased from 26% in M to 61% in MNPK treatment, but the unaccounted K decreased from 72% in M to 37% in MNPK treatment. The findings indicated that integrated application of N, P, and K fertilizers and manure is an important strategy to maintain or increase soil organic C and N, improve soil fertility, maintain nutrients balance, and minimize damage to the environment, while also improving crop yield.     

Effects of compost on the chemical composition of SOM in density and aggregate fractions from rice–wheat cropping systems as shown by solid‐state 13C‐NMR spectroscopy

The 4‐year application of pig‐manure compost (PMC) to crop fields in Jiangsu significantly increased organic‐C and total N concentrations compared to chemical fertilization and control treatment. To identify the soil processes that led to these changes, ¹³C cross‐polarization magic‐angle spinning nuclear‐magnetic resonance (¹³C CPMAS NMR) and dipolar‐dephasing nuclear‐magnetic‐resonance spectroscopy (DD NMR) were conducted on soil organic matter (SOM) fractions separated by wet‐sieving and density fractionation procedures. This allowed characterization of the SOM quality under three contrasting fertilizer regimes. The results indicate that PMC application can alter the distribution of functional groups and improve alkyl C‐to‐O‐alkyl C ratios compared to chemical‐fertilizer treatment (CF). Alkyl C contents were increased from macroaggregate fractions (> 2 mm) to microaggregate fractions (0.05–0.25 mm) for all treatments, suggesting that recalcitrant material accumulates in the microaggregate fractions. The O‐alkyl C contents were decreased from macroaggregate fractions (> 2 mm) to microaggregate fractions (0.05–0.25 mm) under CF and PMC treatments, while no consistent trend was found for the control (NF) treatment. The alkyl C‐to‐O‐alkyl C ratios in macroaggregates were lower than those in microaggregates, indicating that the degrees of SOM decomposition were lower in macroaggregates compared to microaggregates. In all aggregate‐size classes, the amount of organic matter appeared to depend on the fertilization regime. This study provides useful information regarding the buildup of organic material in soil from long‐term manure‐compost enrichment.     

How different long‐term fertilization strategies influence crop yield and soil properties in a maize field in the North China Plain

The impact of fertilization on maize (Zea mays L.) yield and soil properties was investigated in a long‐term (> 18 y) experimental field in N China. A completely randomized block design with seven fertilizer treatments and four replications was used. The seven fertilizer treatments were (1) compost (COMP), (2) half compost plus half chemical fertilizer (COMP1/2), (3) balanced NPK fertilizer (NPK), (4–6) unbalanced chemical fertilizers without one of the major elements (NP, PK, and NK), and (7) an unamended control (CK). In addition to maize yield, soil chemical and biological properties were investigated. Compared to the balanced NPK treatment, maize yield from the COMP treatment was 7.9% higher, from the COMP1/2 was similar, but from the NP, PK, NK, and CK treatment were 12.4%, 59.9%, 78.6%, and 75.7% lower. Across the growing season, microbial biomass C and N contents, basal soil respiration, and fluorescein diacetate hydrolysis, dehydrogenase, urease, and invertase activities in the COMP and COMP1/2 treatments were 7%–203% higher than the NPK treatment. Values from all other treatments were up to 60% lower than the NPK treatment. Maize yield is closely related to the soil organic C (OC) and biological properties, and the OC is closely related to various biological properties, indicating that OC is a suitable indicator for soil quality. Our results suggest the most limiting nutrient for improving the yield or soil quality was P, followed by N and K, and balanced fertilization is important in maintaining high crop yield and soil quality. Additionally, increases in OC, N, and biological activities in COMP and COMP1/2 treatments imply that organic compost is superior to the chemical fertilizers tested.     

长期施肥对栗褐土有机碳矿化的影响

【目的】 土壤有机碳矿化是土壤中重要的生物化学过程,与土壤养分的释放、土壤质量的保持以及温室气体的形成密切相关。本文以 25 年长期定位施肥试验为依托,对栗褐土土壤有机碳矿化速率、有机碳累积矿化量的动态变化进行研究,为科学管理土壤肥力、增加栗褐土碳汇、减少温室气体排放提供依据。 【方法】 田间试验开始于 1988,共设置 8 个施肥处理:不施肥 (CK);单施氮肥 (N);氮磷肥合施 (NP);单施低量有机肥(M₁);低量有机肥与氮肥合施 (M₁N);低量有机肥与氮磷肥合施(M₁NP);高量有机肥与氮肥合施 (M₂N);高量有机肥与氮磷肥合施 (M₂NP)。于 2013 年玉米播种前,采集耕层 (0—20 cm) 土壤样品,采用室内培养方法,对土壤碳矿化释放 CO₂ 的数量和速率进行测定,并利用一级动力学方程计算出土壤有机碳库潜在矿化势和周转速率。 【结果】 各肥料处理不同程度地提高了栗褐土总有机碳含量,以高量有机肥与化肥配施作用最为显著。与 CK 相比,M₂N、M₂NP 处理土壤总有机碳含量增加了 121.1%、166.8%。不同处理土壤样品培养有机碳矿化速率均在第一天达到峰值,随后急剧下降。5 d 后,下降趋缓,不同处理 CO₂ 产生速率趋于一致。培养期间,各处理矿化速率变化符合对数函数关系。长期施用不同肥料均可以提高栗褐土有机碳的矿化速率,其大小顺序为:有机肥与化肥配施 > 单施有机肥 > 单施化肥 > 对照。培养 57 d 后,各处理土壤有机碳累积矿化量为 555.0～980.3 mg/kg,以 M₂NP、M₁N 的累积量较高,为对照的 1.77 倍、1.73 倍。长期施肥栗褐土有机碳矿化率呈下降趋势,以处理 M₂NP 下降最明显,与对照相比,降低了 6.3 个百分点。施肥处理土壤的潜在矿化势均高于对照,M₁N、M₂NP 最高,为 923.7 mg/kg 和 926.4 mg/kg,较对照增加了 74.0% 和 74.5%。不同施肥处理均可明显提升土壤有机碳的周转速率,减少周转时间,其中处理 M₁NP、M₂NP 效果最为明显。 【结论】 长期施用化肥、有机肥及有机无机肥配施可有效促进栗褐土有机碳的积累,提高有机碳的矿化速率和周转速率,降低有机碳的矿化率 (累积矿化量占有机碳总量的比率),加强了土壤的固碳能力,以 M₂NP 处理的效果更佳。      

长期不同培肥措施下玉米产量稳定性及棕壤氮素累积分布特征

  【目的】  研究长期不同培肥措施下玉米产量的稳定性、可持续性和土壤矿质氮累积分布、微生物量氮含量特征,为制定合理的施肥措施和保证东北棕壤地区农业的可持续绿色发展提供理论依据。  【方法】  棕壤肥料长期定位试验始于1979年。选取其中的12个处理:不施肥对照(CK)、单施氮肥(N)、氮磷肥配施(NP)、氮磷钾肥配施(NPK)、低量有机肥(M1)及其与化肥配施(M1N、M1NP和M1NPK)、高量有机肥(M2)及其与化肥配施(M2N、M2NP和M2NPK),分析长期施肥下玉米产量的变化,并于2018年在玉米收获期采集植株和土壤样品,阐明玉米地上部吸氮量变化,0—100 cm土层土壤矿质氮分布、累积及微生物量氮含量的差异。  【结果】  长期不同施肥下玉米产量呈波动变化,且在1979—1998年内玉米产量变化趋势较平稳,1999—2018年内变幅较大。M1NPK、M2NPK处理玉米平均产量最高,在试验前20年较NPK处理分别提高了10.3%、11.7%,后20年分别提高了17.1%、19.4%。随着试验年限增加,玉米产量的稳定性和可持续性增加,有机肥配施化肥各处理高于单施化肥处理,在试验前20年和后20年玉米产量的可持续性指数(SYI)介于0.43～0.58和0.50～0.67,低量有机肥配施处理高于高量有机肥配施处理。配施有机肥各处理肥料贡献率高于单施化肥处理,且试验后20年M1NPK处理肥料贡献率最高,达54%。施肥40年后(2018年)玉米地上部吸氮量以M1NPK处理最高(302 kg/hm2),与M2NPK处理差异不显著。配施低量有机肥玉米收获期80—100 cm土层土壤矿质氮含量较低,M1NPK处理 0—100 cm土层土壤矿质氮贮量为127 kg/hm2,显著低于M1N和M1NP处理。而高量有机肥配施各处理0—100 cm土层土壤矿质氮贮量较化肥试区和低量有机肥试区分别增加了324.5%和172.9%,增加了氮素损失风险。此外,长期配施有机肥处理0—40 cm土层土壤微生物量氮含量增加,但低量和高量有机肥试区各处理间差异不显著。  【结论】  长期不同培肥措施会影响玉米产量的稳定性和可持续性,改变土壤氮素分布和累积,进而影响玉米氮素吸收。低量有机肥(13.5 t/hm2)配施氮磷钾化肥可促进玉米生长和氮素吸收,降低0—100 cm土层土壤矿质氮贮量,降低氮素损失风险,增加微生物量氮含量,较高的微生物量氮又可作为有机氮库来增加土壤供氮并固持易损失的矿质氮和肥料氮,以保证玉米的高产稳产和环境友好。     

长期施肥对水稻土碳氮矿化与团聚体稳定性的影响

水稻土有机碳、氮矿化过程对水稻土质量和作物养分吸收具有重要的作用,但是它们对施肥措施的响应及其与土壤结构之间的关系尚不清楚。本研究基于红壤性水稻土长期施肥定位试验,分析了不施肥(CK)、施用常量化肥(NPK)、2倍化肥(NPK2)和常量化肥配施有机肥(NPKOM)等处理下水稻土碳氮矿化特征,并研究了其与土壤团聚体稳定性的关系。结果表明NPKOM处理显著提高了土壤有机碳和全氮含量(P0.05),而单施化肥处理(NPK2和NPK)则同CK处理没有显著差异。土壤有机碳矿化速率、累积矿化量和矿化率均为NPKOMNPK2NPKCK处理,其中NPKOM处理显著高于其他处理(P0.05),而后3个处理间没有显著差异。土壤氮矿化速率、累积矿化量和矿化率同土壤碳矿化的规律一致,NPKOM、NPK2和NPK处理累积矿化氮量较CK处理分别提高110.0%、29.4%和8.8%,矿化率分别提高110.8%、25.6%和13.0%。单施化肥处理(NPK和NPK2)的平均质量直径(MWD)分别降低了17.1%和15.5%,而NPKOM处理则增加了19.4%。相关分析表明,土壤碳氮矿化主要取决于土壤有机碳氮含量,而与土壤团聚体水稳定性无直接关系。在今后研究中,应重点分析土壤孔隙结构与有机碳氮周转的关系。     

适量有机肥与氮肥配施方可提高河西绿洲土壤肥力及作物生产效益

【目的】 河西绿洲灌溉农业区是我国主要的商品粮生产及玉米制种基地,结合当地耕作制度进行土壤有效培肥是提高农业生产效益和可持续发展的基础。本研究以河西灌漠土长期定位试验为依托,探讨了长期施用一种或者多种有机肥以及有机无机肥配合对土壤养分、土壤酶活性及产量的影响,为筛选出适于当地农业可持续发展的施肥模式提供理论依据。 【方法】 试验采用随机区组排列,除对照外,在施磷肥 (P₂O₅) 150 kg/hm2 的基础上,再设 12 个处理:单施用农家肥 120 t/hm2 (M);单施绿肥 45 t/hm2 (G);单施秸秆 10.5 t/hm2 (S);单施氮肥 375 kg/hm2 (N);农家肥 60 t/hm2 + 绿肥 22.5 t/hm2 (1/2MG);农家肥 60 t/hm2 + 秸秆 5.25 t/hm2 (1/2MS);农家肥 60 t/hm2 + 氮肥 187.5 kg/hm2 (1/2MN);绿肥 22.5 t/hm2 + 氮肥 187.5 kg/hm2 (1/2GN);秸秆 60 t/hm2 + 氮肥 187.5 kg/hm2 (1/2SN);农家肥 40 t/hm2 + 绿肥 15 t/hm2 + 氮肥 124.5 kg/hm2 (1/3MGN);农家肥 40 t/hm2 + 秸秆 3495 kg/hm2 + 氮肥 124.5 kg/hm2 (1/3MSN);农家肥 30 t/hm2 + 秸秆 2625 kg/hm2 + 绿肥 11.25 t/hm2 + 氮肥 94.5 kg/hm2 (1/4MGSN)。调查了耕层土壤有机质和速效养分含量变化以及几种主要土壤酶活力,采用主成分分析、聚类分析、经济效益分析综合比较了不同施肥方式对土壤质量与经济收益的影响。 【结果】 长期不施肥、单施氮肥(N)、氮肥配施绿肥或者秸秆均会造成土壤钾素匮缺,较 1988 年初测土土壤速效钾含量分别下降了 16.59%、39.37%、25.04%、23.31%;M、G、S 三种有机肥单施或与氮配施均能提高土壤碱解氮、土壤有效磷、土壤有效钾、土壤有机质(SOM)含量,不同施肥方式下,其含量大小总体表现为高量有机肥 > 减量有机肥 + 减量 N > N > CK;M、G、S、N 单施或 1/2MN、1/2GN、1/2SN 处理均能提高蔗糖酶、磷酸酶、脲酶、过氧化氢酶活性,以 G、1/2GN 处理对提高土壤蔗糖酶、脲酶的活性的效果最显著,M、G、MN、GN 处理对提高碱性磷酸酶活性的效果最显著;主成分得分进行聚类分析,不同处理培肥土壤质量效果由高到低分成四类,分别为一类高量有机肥 M、G、1/2MG > 二种有机肥与氮肥减量配施 1/2MN、1/3MSN、1/3MGN、1/2GN、1/2MS、1/4MSGN > 三类氮肥、秸秆、秸秆与氮肥 N、1/2SN、S > 四类不施肥(CK);各施肥方式均能提高作物产量,与不施肥(CK)相比,增产幅度为 12.21%～235.4%,肥料贡献率在 10.89%～70.18% 之间,单施肥增产总趋势为 N > G > M > S,减量配施肥增产总趋势为 1/2GN > 1/2MN>1/2MS,施肥方式以有机肥配施 N 对产量贡献最大;经济效益分析表明施 N 或有机肥与 N 配施对于提高净收益作用较大。 【结论】 通过主成分分析与聚类分析、经济效益与产量综合比较,农家肥、绿肥和秸秆长期单施成本高,产量和经济效益低,维持土壤养分和产量需要的用量大。因此,提倡适量有机肥与氮肥配施,达到提高作物产量,增加经济效益,保证土壤肥力可持续发展。      

基于长期定位试验的水稻土氮素剖面分布及养分供应特性研究

基于已持续26年的水稻土长期定位试验,研究了长期施肥对水稻土剖面氮素迁移分布和C/N的影响,不同施肥方式下土壤氮素矿化曲线和硝化强度变化,以及累积矿化量与有效积温的关系,结果表明:(1)长期施肥使土壤表层氮素累积量明显增加,土壤剖面含氮量分布曲线呈"S"形。0-20 cm土层,施有机肥处理的含氮量普遍高于施化肥处理,20-30 cm土层,化肥氮 磷处理(CNP)、化肥氮 磷 钾处理(CNPK)、秸秆 化肥氮处理(CRN)和不施肥对照C0的含氮量高于有机肥 氮 磷处理(MNP)、有机肥 氮 磷 钾处理(MNPK)、秸秆 有机肥 氮处理(MRN)和仅施有机肥处理(M0),而40-50 cm土层含氮量差异较小;(2)土壤矿化曲线在前期差异明显,7 d后的矿化量普遍达最大,28 d后趋于稳定,施有机肥处理7 d后的矿化量明显高于施化肥处理。土壤累积矿化量与有效积温的关系符合有效积温方程式,矿化常数K和n值反映了施有机肥土壤氮素的矿化潜力较大,而施化肥土壤的矿化过程达稳定状态需更长时间;(3)长期施肥使土壤的硝化强度明显提高,施有机肥处理普遍高于施化肥处理。MNPK最高,比C0提高了6.44倍,秸秆还田处理CRN高于CNP和CNPK;(4)施有机肥或秸秆使表层土C/N值有降低趋势。0-10 cm表层土壤的C/N值,CNPK>MNPK,C0>M0,而秸秆还田处理MRN的C/N值最低。20-50cm土层,施有机肥处理的C/N普遍高于化肥处理,施化肥土壤下层的有机质分解程度较高。     

Chemical soil properties and bromegrass hay composition as affected by 23 annual fall and spring applications of ammonium nitrate and urea

Abstract

The influence of nitrogen (N) fertilization on grass forage yield and quality as well as soil properties may vary with type of N fertilizer and time of application. The effects of 23 annual applications (from 1974 to 1996) of ammonium nitrate (AN) and urea (112 kg N ha^‐1) applied in early fall, late fall, early spring and late spring on chemical soil properties and composition of bromegrass hay were evaluated in a field experiment on a thin Black Chernozemic soil located near Crossfield, Alberta, Canada. The influence of N addition, fertilizer type and application time on the soil properties was most pronounced in the 0–5 cm layer and declined in deeper soil layers. Application of N increased extractable ammonium (NH₄)‐N, zinc (Zn), and iron (Fe) in the 0–5 cm layer; and sodium (Na), aluminum (Al), and manganese (Mn) in the 0–10 cm layer. But, N addition reduced extractable phosphoras (P) in the 0–30 cm; potassium (K) in the 0–60 cm; and pH, calcium (Ca), and magnesium (Mg) in the 0–5 cm soil layers. There was little effect of N fertilization on nitrate (NO₃)‐N in soil. Soil pH, and extractable Ca and Mg in the 0–5 cm layer and Zn in the surface 15‐cm soil depth were lower with AN compared to urea, whereas the opposite was true for Fe, Mn, and Cu in the 0–5 cm layer and Na and Al in the top 15‐cm soil depth. Most of the changes in chemical soil properties due to N fertilization were reflected in elemental concentration of bromegrass hay, except for the increase of P concentration in bromegrass with N fertilization. In bromegrass hay for example, N addition increased total N and Cu with both N fertilizers and Mn and Zn with AN, but it lowered K and Ca with both fertilizers. There was more N and less Na with AN than urea in bromegrass hay. The effect of application time on chemical soil properties and composition of bromegrass hay was much less pronounced than N addition and fertilizer type. In conclusion, both N fertilizers changed chemical soil properties and composition of bromegrass hay, but the effects of 23 annual applications on soil properties were confined to shallow soil layers only. The greater lowering of soil pH with AN than urea may have implications of increased liming costs with AN.     

长期施肥对黄土丘陵区土壤理化性质的影响

根据18年的长期定位试验，探讨了不同施肥处理对黄土丘陵区栗褐土土壤容重、土壤结构、孔隙性、水分物理性质以及对土壤有机质和土壤氮，磷含量的影响。结果表明，长期施用有机肥有利于保持和改善土壤孔隙状况，促进水稳性团聚体的形成，提高土壤的透水性和持水能力。单施化肥与不施肥相比，土壤物理性质有所改善，但与初始值比较则变劣。有机肥与化肥配合施用，可减轻化肥对土壤物理性质的不良影响。长期不施肥土壤物理性质有恶化趋势。单施有机肥和有机无机肥配合施用可显著提高土壤有机质和氮、磷含量，有机无机肥配合施用效果更明显，单施化肥的效果不显著。     

黄土高塬沟壑区农田土壤养分与作物产量变化的长期监测

【目的】 土壤养分含量是反映土壤肥力状况的重要指标,对农田肥料投入和土壤养分进行长期定位监测,有利于准确反映土壤养分变化趋势。利用黄土高塬沟壑区不同施肥监测区 10 年的长期监测资料,分析对比不同监测区土壤养分含量和作物产量的变化,分析土壤养分、产量与施肥的关系,为当地农田生产的施肥管理提供理论依据。 【方法】 本研究试验监测区的农田管理完全参照大田管理模式,共设置四大试验监测区,包括无肥监测区(CK)、化肥监测区(HF)、化肥有机肥监测区(HM)和农民地块监测区(NM),肥料均于作物播种前作为基肥撒施。在每年冬小麦收获期 6 月中下旬,或玉米收获期 9 月中下旬,采集表层(0—20 cm)土壤样品,处理后进行土壤养分的分析,并且在作物收获期测算作物产量以及植株地上部分的氮、磷、钾含量。 【结果】 与试验前相比,CK 监测区土壤有机质降低 1.73 g/kg,HF监测区增加 1.97 g/kg,HM监测区增加 2.20 g/kg,NM 监测区增加 1.44 g/kg;CK 监测区土壤全氮减少 0.08 g/kg,其他施肥监测区增加 0.05～0.13 g/kg;HF 监测区土壤碱解氮增加 7.8 mg/kg,而其他监测区均不同程度地降低;HM 监测区土壤有效磷增加最为显著,增幅达到 11.86 mg/kg,HF 监测区增加 8.42 mg/kg,NM 监测区增加 3.06 mg/kg,CK 监测区增加 2.44 mg/kg;CK 监测区土壤速效钾明显下降,降低 38 mg/kg 左右,NM 监测区增加最为显著,增加量为 27.5 mg/kg。对冬小麦而言,相比于 CK 不施肥区,HF、HM 和 NM 监测区都能够显著提高产量,但各施肥监测区之间产量差异不显著。农田养分平衡分析表明,化肥和有机肥配施,可使土壤中 N、P、K 素均有盈余;只施化肥时会导致土壤 K 素亏缺严重;当土壤长期不施用任何肥料时,土壤各养分元素均出现亏缺。 【结论】 在黄土高塬沟壑区,作物生育期降水量及其分配、积温条件和肥力水平对小麦产量影响显著。施肥 10 年后,各施肥区土壤有机质、全氮、有效磷和速效钾含量都有不同程度的提高,土壤碱解氮只有单施化肥的增加。无肥监测区由初始含量的最高水平最终降至最低,证明了长期施肥对于土壤肥力的维持具有重要意义。另外,该地区农民地块存在过量施肥现象。      

不同施肥模式对设施土壤CO2排放特征及碳平衡的影响

  目的  探讨不同施肥模式对土壤CO₂排放特征及碳平衡的影响,为设施土壤固碳减排和合理施肥提供数据支持。  方法  以“粉太郎”番茄为试材,基于设施微区试验,利用LI-8100A土壤碳通量自动测定仪观测了不同施肥模式[50%化肥N + 50%有机肥N + 改良剂组（HYG）、50%化肥N + 50%有机肥N组（HY）、100%有机肥N组（Y）、100%化肥N组（H）和不施肥处理组（CK）]土壤CO₂的排放特征,探讨了土壤含水量、温度、pH、全氮、微生物生物量碳、土壤孔隙度、土壤有机质等因子对CO₂排放量的影响。  结果  在番茄生长初期和施肥后,设施土壤CO₂排放速率均表现为先升高后下降的趋势,土壤含水量和土壤温度的双因素复合模型可以解释76.0%（P < 0.01）土壤CO₂排放速率的变化,不同施肥模式下造成土壤水热环境的变化会显著影响土壤CO₂排放速率。整个生育期,不同施肥模式之间土壤CO₂排放累积量差异显著（P < 0.05）,相比CK处理,施入肥料的H、Y、HY和HYG处理的土壤CO₂排放累积量分别提高了26.7%、83.2%、47.3%和44.2%。相关分析表明,土壤CO₂排放累积量与土壤pH、全氮、微生物量碳、土壤孔隙度和有机质均呈极显著正相关关系(P < 0.01)。HYG处理相较其余各施肥处理可以显著提高番茄产量和总生物量,提高幅度分别为9.4% ~ 38.2%和9.0% ~ 32.9%。HYG处理相较当前设施土壤施肥方式（HY处理）显著降低土壤碳释放总量和作物碳排放效率,降幅分别为2.2%和10.9%,同时HYG处理可以使生态系统固碳潜力增加（11.5%）。  结论  从固碳减排的角度,50%化肥N + 50%有机肥N + 改良剂处理是辽宁地区设施番茄栽培适宜的施肥模式。     

Decadal Nitrogen Fertilization Decreases Mineral‐Associated and Subsoil Carbon: A 32‐Year Study

Crop residues and manure are important sources of carbon (C) for soil organic matter (SOM) formation. Crop residue return increases by nitrogen (N) fertilization because of higher plant productivity, but this often results only in minor increases of SOM. In our study, we show how N fertilization and organic C additions affected SOM and its fractions within a 32‐year‐long field‐experiment at Puch, Germany. Five organic additions, no‐addition (control), manure, slurry, straw and straw + slurry, were combined with three mineral N fertilization rates (no, medium and high fertilization), which resulted in 1·17–4·86 Mg C‐input ha^‐1 y^‐1. Topsoil (0–25 cm) SOM content increased with N fertilization, mainly because of the C in free light fraction (f‐LF). In contrast, subsoil (25–60 cm) SOM decreased with N fertilization, probably because of roots' relocation in Ap horizon with N fertilization at the surface. Despite high inputs, straw contributed little to f‐LF but prevented C losses from the mineral‐associated SOM fraction (ρ > 1·6 g cm^‐3) with N fertilization, which was observed without straw addition. Above (straw) and belowground (roots) residues had opposite effects on SOM fractions. Root C retained longer in the light‐fractions and was responsible for SOM increase with N fertilization. Straw decomposed rapidly (from f‐LF) and fueled the mineral‐associated SOM fraction. We conclude that SOM content and composition depended not only on residue quantity, which can be managed by the additions and N fertilization, but also on the quality of organics. This should be considered for maintaining the SOM level, C sequestration, and soil fertility. Copyright © 2016 John Wiley & Sons, Ltd.     

不同施肥模式对设施菜田土壤微生物量碳、氮的影响

【目的】 本文利用天津日光温室蔬菜不同施肥模式定位试验,研究了不同施肥模式对设施菜田土壤微生物量碳、氮含量的影响,为设施蔬菜高效施肥和菜田土壤可持续利用提供依据。 【方法】 调查在第 9 茬蔬菜 (秋冬茬芹菜) 和第 10 茬蔬菜 (春茬番茄) 进行。定位试验设 8 个处理,分别为:1) 不施氮;2) 全部施用化肥氮 (4/4CN);3) 3/4 化肥氮 + 1/4 猪粪氮 (3/4CN + 1/4PN);4) 2/4 化肥氮 + 2/4 猪粪氮 (2/4CN + 2/4PN);5) 1/4 化肥氮 + 3/4 猪粪氮( 1/4CN + 3/4PN);6) 2/4 化肥氮 + 1/4 猪粪氮 + 1/4 秸秆氮 (2/4CN + 1/4PN + 1/4SN);7) 2/4 化肥氮 + 2/4 秸秆氮 (2/4CN + 2/4SN);8) 农民习惯施肥 (CF),除不施氮肥和农民习惯施肥外,其余处理为等氮磷钾处理。在不同生育时期,采 0—20 cm 土壤样品,测定土壤微生物量碳、氮含量,并分析其与蔬菜产量之间的关系。 【结果】 两茬蔬菜不同施肥模式土壤微生物量碳、氮含量总体上均随生育期的推进呈先增后降的趋势。芹菜季较高土壤微生物量碳含量出现在定植后 90 d,土壤微生物量氮较高含量出现在定植后 60 d;番茄季分别出现在定植后 20～80 d 和 60 d。芹菜季 5 个有机无机肥料配施模式土壤微生物量碳、氮含量分别在 185.0～514.6 和 34.3～79.1 mg/kg 之间,较化肥(4/4CN)模式平均分别增加 15.1%～81.7% 和 24.5%～100.0%,其中以配施秸秆模式土壤微生物量碳、氮含量相对较高,平均分别增加 62.0%～81.7% 和 81.1%～100.0%;番茄季 5 个有机无机肥料配施模式土壤微生物量碳、氮含量分别在 120.7～338.0 和 25.5～68.8 mg/kg 之间,较 4/4CN 模式平均分别增加 16.9%～86.9% 和 12.2%～109.3%,又以配施秸秆模式土壤微生物量碳、氮含量最高,平均分别增加 61.4%～86.9% 和 78.2%～109.3%。两季蔬菜不同生育期土壤微生物量碳、氮含量与当季蔬菜产量和定位试验开始以来蔬菜总产量之间均呈极显著正相关关系。 【结论】 同等养分投入量下,有机无机肥料配合施用提高土壤微生物量碳、氮的效果显著好于单施化肥,又以化肥配施秸秆效果更佳;土壤微生物量碳、氮含量与设施蔬菜产量之间呈极显著正相关关系。证明有机无机肥配施,特别是配施一定量的秸秆可有效提高土壤微生物量碳、氮含量,维持较高的菜田土壤肥力,有利于设施蔬菜的可持续和高效生产。