嗜热复合菌对堆肥品质及微生物群落演替的影响

  【目的】  研究嗜热复合菌对畜禽粪污堆肥理化特性和腐熟度的影响,探讨嗜热菌影响堆肥过程的微生物机制。  【方法】  堆料由75%羊粪和25%养鸡发酵床垫料构成,初始原料C/N为28,堆料量1.2 t,高度70～90 cm,开放条垛式堆沤。处理组为堆肥添加0.1%嗜热菌B. fordii FJAT-51578和U. thermosphaericus FJAT-51579等比混合的发酵液,对照组为添加1%市售枯草芽孢杆菌堆肥菌剂(Bacillus subtilis)。堆肥时间为2021年9月18日—10月14日,每两天检测1次温度。堆肥前15天,每两天进行一次翻抛,后期每5天进行一次翻抛,保持堆肥含水量50%～60%,直至高温期结束。在堆肥开始后第1、9和26天取堆肥样品,分析氮磷含量、硝化指数和种子发芽指数。结合扩增子测序,分析堆肥细菌群落结构变化,并揭示其主要环境影响因子。采用PICRUSt分析堆肥有效氮和有效磷代谢的微生物机制。  【结果】  嗜热复合菌添加促进堆肥硝化指数的降低和种子发芽指数的升高,促进堆肥腐熟;堆肥产物碱解氮和有效磷的含量分别比市售菌剂组高11.8%和7.7%。同时,嗜热复合菌的添加改变了细菌群落的分布,降低了堆肥细菌的多样性和丰富度,提高了糖单胞菌、链霉菌和嗜热葡萄孢菌等降解菌的丰度。RDA分析表明,pH和C/N是影响堆肥微生物群落多样性的主要因素,碱解氮与芽孢杆菌和糖单胞菌属丰度正相关,有效磷与嗜热裂孢菌、直丝菌属和马杜拉放线菌属丰度正相关。氮、磷代谢相关京都基因和基因组百科全书同源基因(KO)的PICRUSt分析显示,微生物氮磷循环相关KO的丰度随着堆肥进程均有所增加。添加嗜热菌剂提高了氨化、铵同化、硝酸盐同化、同化/异化硝酸盐还原等氮循环相关KO,及无机磷溶解、酸性磷酸酶和碱性磷酸酶等磷循环相关KO。  【结论】  在畜禽粪污堆肥中添加嗜热复合菌剂加快并延长了高温期,降低了C/N,提高了堆肥中碱解氮和有效磷含量,其中C/N、硝化指数和GI指数等指标在堆肥中期达腐熟程度标准,促进堆肥腐熟。堆肥中添加嗜热复合菌剂增加了细菌氮磷代谢相关KO的表达,提高了腐熟中期堆肥中嗜热菌的丰度和种类,碱解氮与芽孢杆菌和糖单胞菌属丰度呈正相关,有效磷与嗜热裂孢菌、直丝菌属和马杜拉放线菌属丰度正相关。因此,添加嗜热复合菌促进了堆肥有效氮磷的含量。     

Soil physical quality of a Brazilian Oxisol under two tillage systems using the least limiting water range approach

Plant growth is directly affected by soil water, soil aeration, and soil resistance to root penetration. The least limiting water range (LLWR) is defined as the range in soil water content within which limitations to plant growth associated with water potential, aeration and soil resistance to root penetration are minimal. The LLWR has not been evaluated in tropical soils. Thus, the objective of the present study was to evaluate the LLWR in a Brazilian clay Oxisol (Typic Hapludox) cropped with maize (Zea mays L. cv. Cargil 701) under no-tillage and conventional tillage. Ninety-six undisturbed soil samples were obtained from maize rows and between rows and used to determine the water retention curve, the soil resistance curve and bulk density. The results demonstrated that LLWR was higher in conventional tillage than in no-tillage and was negatively correlated with bulk density for values above 1.02 g cm⁻³. The range of LLWR variation was 0–0.1184 cm³ cm⁻³ in both systems, with mean values of 0.0785 cm³ cm⁻³ for no-tillage and 0.0964 cm³ cm⁻³ for conventional tillage. Soil resistance to root penetration determined the lower limit of LLWR in 89% of the samples in no-tillage and in 46% of the samples in conventional tillage. Additional evaluations of LLWR are needed under different texture and management conditions in tropical soils.     

Soil physical responses to novel rice cultural practices in the rice–wheat system: Comparative evidence from a swelling soil in Nepal

Soil puddling in advance of rice (Oryza sativa L.) transplanting disperses surface aggregates and generates compaction at depth. As a management scheme for rice, puddling is typically considered advantageous for maximizing resource availability and yield. However, some experimental findings suggest a conflict between edaphic conditions created by this establishment technique and the performance of subsequent non-rice crops like wheat (Triticum aestivum L.). At a site in the mid-hills region of Nepal on a silt loam soil with vertic characteristics, we compared the impact of six rice tillage (surface tillage—T₁, shank subsoiler—T₂, shank subsoiler + moldboard plough—T₃) and establishment (soil puddling + transplanting—TPR, direct seeding—DSR) combinations on soil physical properties over two cycles of the rice–wheat rotation. For the rice season, 0–20 cm saturated hydraulic conductivity (K_sat) in the DSR plots was 2.6 and 4.3 times higher than their TPR counterparts in the first (Y₁) and second (Y₂) years, respectively (TPR-Y₁ = 93 mm day⁻¹, DSR-Y₁ = 241 mm day⁻¹, TPR-Y₂ = 133 mm day⁻¹, DSR-Y₂ = 582 mm day⁻¹), whereas tillage method did not significantly influence K_sat in this soil layer. The impact of rice establishment method was reflected in higher TPR bulk densities in the 5–10 (DSR = 1.19 g cm⁻³, TPR = 1.24 g cm⁻³) and 10–15 cm (DSR = 1.24 g cm⁻³, TPR = 1.29 g cm⁻³) depth increments in the wet season. Although none of the treatments significantly influenced the position or thickness of the plough sole, penetration resistance profiles suggest that vertical fractures with reduced soil strength were created within the pan region by deep tillage (T₂ and T₃), although these features were not associated with higher hydraulic conductivities from 20 to 50 cm. As the soils dried at the end of the rice season, crack propagation in the deep tilled plots (T₂ and T₃) was more pervasive. During the wheat season, comparable bulk density profiles and soil moisture retention characteristics across the treatments suggest that many of the edaphic changes induced by contrasting rice tillage and establishment practices did not persist in the self-mulching, vertic soils at our site. Conversely, significant increases in K_sat among the DSR plots from Y₁ to Y₂ (Y₁ = 241 mm day⁻¹, Y₂ = 582 mm day⁻¹) imply a temporal element to soil structural regeneration with adoption of direct seeding.     

The effect of urban refuse compost and different tractors tyres on soil physical properties, soil erosion and maize yield

Application of urban refuse compost to agricultural soil could help to solve municipalities' problems related to the increasing production of waste only if soil property improvement and environmental conservation can be demonstrated. The use of low-pressure tractor tyres is another proposal in modern agriculture for reducing soil compaction. This study thus aimed to detect the effects of both compost and low-pressure tractor tyres on soil loss, runoff, aggregate stability, bulk density, penetrometer resistance and maize (Zea mays L.) yield. A 3-year field experiment was carried out on a hilly (15% slope) clay loam soil in central Italy. Twelve plots (200 m² each) were monitored with tipping-pot devices for runoff and soil erosion measurement. Treatments were: compost addition (64 Mg ha⁻¹), mineral fertilisation, use of low-pressure tyres, use of traditional tyres, with three replicates, in a fully randomised block design. Compost was applied once at the beginning of the experiment. Runoff reduction due to compost ranged between 7 and 399 m³ ha⁻¹ during seasons, while soil erosion was reduced between 0.2 and 2.4 Mg ha⁻¹. Mean weight diameter (MWD) of stable aggregates, measured on wheel tracks, increased by 2.19 mm, then progressively decreased. Compost significantly increased bulk density by 0.08 Mg m⁻³ due to its inert fraction content. This effect was less evident in the second and third year, probably due to harrowing. Maize yields were slightly, but significantly, reduced in composted plots by 1.72 Mg ha⁻¹ in the third year. Low-pressure tyres significantly reduced soil loss in the third year by 1 Mg ha⁻¹. Furthermore, they did not significantly influence runoff volumes and soil structural stability. Low-pressure tyres or compost addition were singly able to prevent an increase in penetrometer resistance due to agricultural machinery traffic. Low-pressure tyres increased the maize yield during the 3 years and the difference (0.4 Mg ha⁻¹) became significant in the third year. In conclusion, results show the positive lasting effect of compost in ameliorating soil physical properties and reducing runoff and soil erosion. Low-pressure tyres appear justifiable both for the observed increase of grain production and reduction of soil compaction. This latter effect is, nevertheless, masked by compost addition which is also able to reduce penetrometer resistance. Further research is required to explain the causes of the slight inhibition of grain yield observed when compost was compared with mineral fertilisation.     

Effects of tillage and nitrogen management on soil chemical and physical properties after 23 years of continuous sorghum

Long-term tillage and nitrogen (N) management practices can have a profound impact on soil properties and nutrient availability. A great deal of research evaluating tillage and N applications on soil chemical properties has been conducted with continuous corn (Zea Mays L.) throughout the Midwest, but not on continuous grain sorghum (Sorghum bicolor (L.) Moench). The objective of this experiment was to examine the long-term effects of tillage and nitrogen applications on soil physical and chemical properties at different depths after 23 years of continuous sorghum under no-till (NT) and conventional till (CT) (fall chisel-field cultivation prior to planting) systems. Ammonium nitrate (AN), urea, and a slow release form of urea were surface broadcast at rates of 34, 67, and 135 kg N ha⁻¹. Soil samples were taken to a depth of 15 cm and separated into 2.5 cm increments. As a result of lime applied to the soil surface, soil pH in the NT and CT plots decreased with depth, ranging from 6.9 to 5.7 in the NT plots and from 6.5 to 5.9 in the CT plots. Bray-1 extractable P and NH₄OAc extractable K was 20 and 49 mg kg⁻¹ higher, respectively, in the surface 2.5 cm of NT compared to CT. Extractable Ca was not greatly influenced by tillage but extractable Mg was higher for CT compared to NT below 2.5 cm. Organic carbon (OC) under NT was significantly higher in the surface 7.5 cm of soil compared to CT. Averaged across N rates, NT had 2.7 Mg ha⁻¹ more C than CT in the surface 7.5 cm of soil. Bulk density (Δ_b) of the CT was lower at 1.07 g cm⁻³ while Δ_b of NT plots was 1.13 g cm⁻³. This study demonstrated the effect tillage has on the distribution and concentration of certain chemical soil properties.     

Effects of intensifying organic manuring and tillage practices on penetration resistance and infiltration rate

Soil erosion, along with the contributing factors of soil crusting and sealing, have received minimal scientific attention to date in Latin America. This study was conducted in an Andean hillside environment to determine how the local organic manuring and tillage practices influence the development of soil crusting and sealing, and the extent to which these practices influence soil water infiltration. The aim of this study was to identify treatments that prevented superficial soil structural constraints, i.e. treatments which maintain infiltration and therefore reduce potential soil erosion and run-off.

Treatment results were measured with a pocket penetrometer and a mini-rain simulator on nine different cropping systems, mainly based on cassava (Manihot esculenta Crantz), from February to November 2000 and 2001. The cropping systems were laid out on a Ferrallic Cambisol, an acid, vulcanically influenced soil of the Andean region.

In both cropping cycles, treatments with chicken manure application developed superficial soil crusts during the dry season. For a treatment manured with 8 t ha⁻¹ chicken manure, this crust meant an increase in penetration resistance from 2.3 kg cm⁻² in April 2000 to 16.2 kg cm⁻² in July 2000. The change in superficial soil structure created a notable reduction in final infiltration from 92 to 42.2 mm h⁻¹. A minimum tillage treatment which displayed the highest penetration resistance during the dry periods of up to 46.4 kg cm⁻² presented no restricting effects on soil water intake (76.2 mm h⁻¹ final infiltration in 2000) due to an optimal aggregate development during 10 years of consecutive conservation practice.

Measurements of penetration resistance and infiltration showed that soil conserving treatments, such as minimum tillage and crop rotations, improved the physical soil status and prevented soil crusting developing along with its negative effects on infiltration. These methods can therefore be strongly recommended to farmers.     

用稀悬液Wien效应测量法来研究重金属离子与水稻土的相互作用

Interactions of three heavy metal ions, Cu²⁺, Cd²⁺, and Pb²⁺, and, for comparison, Na⁺ with electrodialytic clay fractions (less than 2 μm in diameter) of four paddy soils as well as a yellow-brown soil as a control soil were evaluated based on measurements of the Wien effect in dilute suspensions with a clay concentration of 10 g kg^?1 in four nitrate solutions of 2 × 10^?4/z mol L^?1, where z is the cation valence, and a nitric acid solution of 3 × 10^?5 mol L^?1. Field strengths ranging from 15 to 230 kV cm^?1 were applied for measuring the electrical conductivities (ECs) of the suspensions. The mean free binding energies between the various cations and all of the soils determined from exchange equilibrium increased in the order: Na⁺ < Cd²⁺ < Cu²⁺ < Pb²⁺. In general, the ECs of the suspensions in the sodium nitrate solution were smaller than those of the suspensions in the heavy metal solutions because of the lower electrophoretic mobility of sodium compared to the divalent cations. In terms of relative electrical conductivity-field strength relationships, relative electrical conductivity (REC) of suspensions containing various cations at field strengths larger than about 50 kV cm^?1 were in the descending order: Na⁺ > Cu²⁺ > Cd²⁺ > Pb²⁺ for all tested soils. A characteristic parameter of the REC-field strength curves, ΔREC₂₀₀, REC at a field strength of 200 kV cm^?1 minus that at the local minimum of the concave segment of the REC-field strength curves, characterized the strength of adsorption of the cations stripped off by the applied strong electrical field, and for all soils the values of ΔREC₂₀₀ were generally in the order: Na⁺ < Cu²⁺ ≤ Cd²⁺ ≤ Pb²⁺.     

Emission of nitric oxide and nitrous oxide from soil under field and laboratory conditions

A detailed short-term (12 d) laboratory study was carried out to investigate the effects of applying animal urine, fertilizer (ammonium nitrate) and fertilizer+urine on emission of NO and N₂O from soil. A complementary 24 d field study measured the effect of fertilizer or fertilizer+sheep grazing on NO and N₂O emissions from pasture. The data generated were used to interpret the transformations responsible for the release of these gases. Application of urine to the soil (at a rate equivalent to 930 kg N ha⁻¹) increased the amount of mineral and microbial N in the soil. This was followed by increases in emissions of NO (from 0.02 to 1.76 mg NO-N m⁻² d⁻¹) and N₂O (from 15 to 330 mg N₂O-N m⁻² d⁻¹). Molar ratios of NO-N-to-N₂O-N were very low (<0.001 to 0.011) indicating that denitrification was the main process during the first 12 d after application. In the laboratory, nitrification was inhibited during the first 7 d due to an inhibitory effect of the urine, but even though nitrification was clearly underway 7–12 d after application, denitrification was still the dominant process. The fertilizer was applied at a lower rate (120 kg N ha⁻¹) than the urine. Consequently, the effect on soil mineral N was smaller. Nevertheless the fertilizer still increased NO and N₂O emission with denitrification the dominant process. The effects of fertilizer and grazing on NO and N₂O emissions was less obvious in the field compared with the laboratory and fluxes returned to background rates within 4 d. This was attributed to the rapid decline in soil mineral N in the field trial due to plant uptake and leaching, processes that did not occur in the laboratory.     

Role of nutrient amendments in the success of half-moon soil and water conservation practice in semiarid Burkina Faso

The half-moon technique has been recently introduced in northern Burkina Faso as a method for the rehabilitation of sealed and crusted bare soils locally called zipellé. As this technique, like zaï and mulching practices, interested many farmers, a trial was conducted to study the effect on soil productivity of half-moon technique in association with different sources of nutrients. The experimental design consisted of treatments in which the half-moon was combined with organic or mineral fertilisers. The soil was a Ferric Lixisol with a rooting depth of 30 cm, low contents of organic matter (12 g kg⁻¹), nitrogen (0.6 g kg⁻¹) and available phosphorus (6.6 mg kg⁻¹). Applying compost or animal manure allowed yields from 900 to 1600 kg ha⁻¹ of sorghum grain, i.e. 20–39 times the yield obtained in the half-moon treatment without any amendment. Combining local rock phosphate to compost in the half-moon basins increased sorghum grain yield by 10% the first year and 26% the second year. This study showed that restoring favourable soil moisture conditions by breaking up the surface crust to improve water infiltration was not enough to improve sorghum production on the degraded zipellé. Removal of the water constraint by destroying the surface hard pan revealed the second major constraint, i.e. soil acidity and nutrient deficiency. Well-decomposed organic matter such as animal manure and compost supplied in the half-moons were good substrates that provided sorghum with the nutrients required for growth. Moreover, adding local rock phosphate to compost appeared to be an alternative for improving soil productivity. It is concluded that in the Sahelian zone, half-moon technique with appropriate nutrient management could be an effective method for the rehabilitation of degraded soil productivity.     

Short-term compost effect on macroaggregation in a sandy soil under low rainfall in the valley of Mexico

Several studies have shown the importance of organic material in the formation and stability of soil aggregates. The organic matter of soil (SOM) is affected among other factors by the application of farmyard waste and compost, as well as tillage and crop rotation. This paper examines the aggregation and stability of a sandy soil (Haplic Fluvisol) in the valley of Mexico when treated with either 40 Mg ha⁻¹ of compost or urea (80 kg ha⁻¹ of N) and sown to amaranth (Amaranthus hypochondriacus L.) under dryland conditions. The application of compost resulted in a significantly larger proportion of aggregates in the fractions >1 mm (1.0–2.0, 2.0–2.3, 2.3–4.7 mm) than in the smaller fraction (<1 mm). However the stability of the macroaggregates >1 mm in the compost treatment was not higher than in contrasting treatments which did not include organic matter. Compost, which was applied under drought conditions, did not increase the aggregate stability of the soil probably because of the restricted transformation of the compost and microorganism activity.     

低蛋白饲喂技术对猪粪好氧堆肥腐熟度的影响

  【目的】  猪粪由于产生量大、碳氮比低、水分含量高等导致储存处理难度较大，好氧堆肥处理猪粪因原料所提供微生物活动环境较差，导致堆肥效率低下。低蛋白饲喂技术在不影响猪生长发育的同时降低了饲料中的氮投入，可以显著改变猪粪的养分组成。本研究通过多种有机肥腐熟指标判定，分析低蛋白含量日粮饲喂的猪粪通过不同堆肥方式是否可快速有效地达到腐熟，并符合安全施用标准。  【方法】  动物试验选取初始体重为60 kg的去势公猪72头，分高、低蛋白饲喂两个处理，每个处理6次重复，每个重复6头猪。试验饲料均适应喂养7天后，开始收集粪便，收粪期为60天。堆肥试验共设4个处理，分别是高蛋白饲喂静态堆肥 (MH)、低蛋白饲喂静态堆肥 (ML)、高蛋白饲喂好氧堆肥 (CH)、低蛋白饲喂好氧堆肥 (CL)，堆肥周期为14天。监测了堆肥过程中堆体温度和碳、氮含量等指标，并测定堆肥处理的小白菜种子发芽指数 (GI)。  【结果】  以堆肥过程中高温持续时间、堆肥NH₄+-N含量、T值 (堆肥结束C/N与堆肥初始C/N的比值) 和GI (小白菜种子发芽指数) 4项为腐熟判断指标，在14天堆肥周期内，高蛋白饲喂产生的猪粪在静态堆肥情况下 (MH)，高温持续时间为0天，NH₄+-N含量为0.43 g/kg、T值为0.91、GI指数为0，未能达到腐熟标准；高蛋白饲喂产生的猪粪堆肥在好氧堆肥条件下 (CH)，高温持续时间为5天，NH₄+-N含量为0.33 g/kg、T值为0.70、GI指数为0.31，T值和GI值均未能达到腐熟标准；低蛋白饲喂产生的猪粪，在静态堆肥中 (ML) 高温持续时间为0 天，NH₄+-N含量为0.54 g/kg、T值为0.81、GI指数为0.25，均未能达到腐熟标准；而在好氧堆肥 (CL) 中，高温持续时间为6天，NH₄+-N含量0.14 g/kg、T值为0.57、GI指数为0.96，均达到腐熟标准。  【结论】  高蛋白饲养产生的猪粪在静态和好样发酵条件下堆放14天，都不能完全腐熟。低蛋白饲喂产生的猪粪在静态堆放条件下，堆肥14天也不能达到腐熟标准。而低蛋白饲养产生的猪粪在好样条件下，可以在堆放14天时达到腐熟，因为低蛋白饲喂技术使猪粪碳氮比提高了约15%，高温发酵时长延长了40%，极大提高了猪粪短时间内的腐熟程度。因此，在循环农业中，通过上游低蛋白饲喂技术可促进下游猪粪的快速处理和循环利用。     

Comparative FT-Raman spectroscopy of Xanthoria lichen-substratum systems from temperate and antarctic habitats

Lichens have a primary role in the biodeterioration of rock substrata and in soil formation. In extreme Antarctic rock-face habitats, their exposed epilithic growth form makes them vulnerable to environmental stress, especially to increased UVB radiation within the late winter ozone “hole”. In this study, FT-Raman spectra of intact epilithic samples of the highly-pigmented lichen species Xanthoria elegans and Xanthoria mawsonii from a continental Antarctic habitat in central Victoria Land and Xanthoria parietina from a maritime temperate location in Scotland have been compared. Vibrational assignments have been made for their pigments, based on parietin and an anthraquinone model. Other significant spectral features are assigned to biodegradative secondary metabolites, cellulose and incorporated substratal rock particles. Differential distribution of parietin pigment bands in the profile of an X. elegans thallus is probably related to the high intensity of UV-radiation reaching its Antarctic cold desert surface environment. The significant differences in Raman spectra between epiphytic X. mawsonii and epilithic X. elegans at the same site possibly indicate different biochemical UV survival strategies. In contrast to spectra from other lichen species studied in our laboratories, the Xanthoria encrustations contain very little calcium oxalate, formed by reaction of oxalic acid with calcareous substrata. The 462 cm⁻¹ ν(SiO) band of quartz is found in the Raman spectra from both upper and lower surfaces of the lichen encrustations, confirms the physical incorporation of the substratum into the thallus.     

Changes in maturity indicators during the degradation of organic wastes subjected to simple composting procedures

Selected maturity indicators were monitored over a period of 335 days during the degradation of organic wastes subjected to four simple composting procedures, which varied in raw material (garden refuse with and without market refuse) and turning frequency (0×, 6×). All procedures produced mature composts. The inclusion of market refuse and frequent turning generally increased the cation exchange capacity of compost on an ash-free basis. Until day 118 of the composting process, compost samples which contained market refuse in their raw material mixture had the lowest redox potentials after anaerobic incubation. Cress grown on these composts also produced the lowest fresh mass. At a later stage of the composting process, the same composts displayed increased cellulolytic activity. Frequent turning of the compost heaps resulted in greater fluorescein diacetate hydrolysis, a greater occurrence of low-molecular-weight humic compounds and, occasionally, an inhibition of cellulolytic activity. The arginine ammonification assay gave information on the N-status of the composts, rather than on the compost maturity, and suggested that all the composts could be safely applied to soil with no risk of microbial immobilisation of soil N.     

基于卷积神经网络的堆肥腐熟度预测

【目的】目前堆肥腐熟度主要采用复杂的化学、生物学方法进行判断,操作繁琐且效率低。卷积神经网络 (convolutional neural network,CNN) 模拟人类视觉,既可保留堆肥图像的颜色信息,也提取了轮廓、线条、粒度等更加具有代表性的特征,从而避免了因光照条件不同对堆肥腐熟度预测识别效果的影响。本文提出了通过堆肥图像判断堆肥腐熟度的方法,构建基于卷积神经网络的堆肥腐熟度预测模型,并验证了该模型进行堆肥腐熟度判断的准确度。【方法】供试堆肥样本采集自江苏、山东、浙江三省,堆肥原料分别为秸秆、尾菜和畜禽粪便,堆肥周期依次为50 d、45 d和60 d。在厂棚内的堆肥槽中,用海康威视摄像头 (型号为C3W,焦段为广角,焦距2.8 mm,清晰度1080 p,夜间自动补光,摄像头距堆肥表面约1 m) 拍摄不同腐熟时期的堆肥图像,图像格式为JPEG。分别取三种不同原料的堆肥图像样本构成三组图像数据集,将三种原料的图像按照尾菜∶秸秆∶畜禽粪便原料1∶1∶1构成第四组图像数据集。每组数据集中,80%的图像数据用于训练基于卷积神经网络模型,并建立预测模型参数。剩余20%的图像用于测试,验证模型的腐熟度预测效果。【结果】搭建的堆肥腐熟度预测模型由输入层、3层卷积层、3层池化层、2层全连接层和输出层构成。构建的腐熟度预测模型在秸秆、尾菜、畜禽粪便及三者堆肥混合图像数据集上的腐熟度预测平均准确率分别为98.7%、98.7%、98.8%和98.2%。与几种经典高效的图像特征提取、分类方法相比,较每个数据集上最优经典算法的平均准确率提升了3～14个百分点。通过CNN方法判断堆肥腐熟度,纹理特征比颜色特征更加有效。【结论】采用卷积神经网络的堆肥腐熟度预测模型能够提取堆肥图像外观特征,实现在可见光条件下直接通过堆肥图像准确、快速地识别堆肥腐熟度,可为堆肥企业生产实践提供指导。     

Feedstock Carbon Influence on Compost Biochemical Stability and Maturity

Quantity and quality of readily degradable carbon influences the composting process especially for compost mixture high in lignocellulotic material. Effects of carbon source on stability and maturity of compost from in-vessel systems are poorly understood. Research was conducted to investigate the effects of carbon composition of feedstock on the evolution of stability indices and reliability of maturity tests for accelerated vessel composting systems. Rice straw, sugarcane bagasse, and coffee hulls were composted in a modified rotary in-vessel composter amended with either cattle or sheep manure. Distinct evolution patterns were observed across carbon sources for temperature, with the sugarcane compost never attaining thermophilic temperatures. Time to peak temperature and return to ambient were significantly different between the rice and coffee compost. Comparatively, organic matter degradation followed a similar pattern for all carbon sources, although rice straw showed the faster degradative rate and coffee hulls the greatest overall loss. Both pH and electrical conductivity were inappropriate stability indices across carbon sources, while the NH₄⁺/NO₃^? ratio was lower than the threshold from week 1. The Solvita® maturity test was the best suited quality indicator and was related to compost respiration. The rice compost at week 12 was the only mature compost with an index value of 7. However, the coffee compost was in the curing stage with a value of 6. In vitro phytotoxicity assays on hot pepper contrasted the Sovita® interpretation for rice compost, which showed the lowest germination index. All compost had a stimulatory effect on cucumber seeds. In vivo seeding assays corroborated in vitro results with rice compost showing the greatest negative effect, augmented at 100% compost inclusion. Carbon source significantly influenced compost stability and maturity indices, which suggests that greater attention should be directed to quality indices in relation to feedstock composition.     

Chemical and microbiological parameters for the characterization of maturity of composts made from farm and agro-industrial wastes

Bioconversion of farm wastes with agro-industrial wastes into enriched compost is an important possibility in need of research. In this article, changes in chemical and microbiological parameters were evaluated to determine the maturity of composts prepared from mixture of farm and agro-industrial wastes over a period of 150 days. Seven different composts were prepared by using a mixture of different farm wastes with or without enrichment with rock phosphate (RP), agro-industrial wastes and the inoculation of microorganisms. As composting proceeded, the organic C, water-soluble C (WSC), bacterial and fungal counts decreased, whereas total N, P, electrical conductivity (EC) and actinomycetes count increased gradually. Our results suggest that WSC <1%, C:N ratio < 20, neutral pH and a decrease in bacteria and fungal counts, along with an increase in actinomycetes count and stability at the end of composting, may be accepted as an indicator of compost maturity. Changes in organic C, EC, total N and P concentrations over time also proved to be reliable indicators of the progress of the composting process for establishing stability and compost maturity. Addition of RP, agro-industrial wastes and inoculation of microorganisms showed potential in improving the N and P contents of the composts.     

Effect of different tillage systems on the quality and crop productivity of a clay–loam soil in semi-arid north-western Turkey

A 2-year study was conducted to investigate the effect of three tillage systems on the properties of clay–loam soil (EutricVertisol) planted with winter wheat (Triticum aestivum L.) in the Canakkale province of north-western Turkey. Crop productivity was also evaluated. The three tillage treatments were: (1) conventional tillage involving mouldboard ploughing followed by two discings (MT); (2) shallow tillage consisting of rototilling followed by one discing (RT); (3) double discing (DD). In the first year of the study, bulk density (BD) was found significantly lower under RT at both 0–10 and 10–20 cm depths with 1.24 and 1.32 Mg cm⁻³, respectively, when compared to MT treatment. However, MT at 20–30 cm provided the highest BD, at 1.49 Mg cm⁻³. In the second year of the study, DD had the lowest BD at all depths followed by RT and MT. Based on the 2-year mean, aggregate size distribution (ASD) and mean weight diameter (MWD) were significantly influenced by tillage treatments. The greatest MWD was obtained with DD, followed by MT and RT. Increasing MWD and coarse aggregates decreased seedling emergence. Organic carbon increased after RT, DD, and MT by 58%, 30%, and 18%, respectively, when compared to the amount at the beginning of the study. Similarly, the total N in the soil and straw was higher after RT than the other treatments. At 1.76 MPa, penetration resistance at 18–30 cm was significantly higher during the growing period using DD, followed by RT with 1.35 MPa and MT with 1.33 MPa. There was no significant difference between treatments at 0–18 cm. Increasing OC and total N and decreasing BD and PR under RT increased grain yield to 4611 kg ha⁻¹, followed by MT and DD at 4375 and 4163 kg ha⁻¹, respectively, according to the 2-year mean.     

Soil fertility properties on Agave angustifolia Haw. plantations

This study examined the variations in soil physical, chemical and biological properties from Agave angustifolia fields in three sites with different topographic conditions (valley, hill and mountain), in Oaxaca, Mexico, associated with the tillage systems, disk ploughing (DP), animal drawn ploughing (ADP) and minimum tillage (MT), respectively. Plant ages were 1.5–3.5 years (class 1), 3.6–5.5 years (class 2) and 5.6–7.5 years (class 3). Soil samples were taken at two soil depths (0–20 and 21–40 cm) from plots of 4000 m² within each site and plant age classes, during the spring of 2005. The main changes in soil properties were found in the mountain site. Soil bulk density (2.0 g cm⁻³), cone penetration resistance (CPR) (3.96 MPa), 0.7 and 1.0 mm water stable aggregates (WSA) (28.3 g kg⁻¹ and 102.2 g kg⁻¹, respectively) were higher in the mountain site than in the hill and valley fields. This result is consistent with the rocky substrate beneath the shallow soil. Soil organic carbon (SOC) (23.9 g kg⁻¹), available N (23.1 mg kg⁻¹) and soil microbial biomass carbon (SMBC) (969.6 μg g⁻¹) at the mountain site showed the highest values, suggesting that MT practiced in this topographic condition favours the organic matter accumulation and biological activity. Soil microbial biomass carbon and SOC seem to be the soil properties that were mainly affected by the sites and soil management associated with them. For the three sites, SOC, P_Olsen, available N, exchangeable Na⁺ and SMBC were higher at 0–20 cm depth than at 21–40 cm depth within each site. Exchangeable Ca²⁺ and K⁺, P_Olsen and CPR increased with plant age. In contrast, available N decreased. Soil chemical properties were more affected by the age of the plant than physical and biological properties. Results reported here represent a reference of the fertility properties of soils cultivated with A. angustifolia, which could be used in further studies focused on management and tillage systems.     

微生物菌剂对猪粪堆肥过程中堆肥理化性质和优势细菌群落的影响

  【目的】  掌握猪粪堆肥过程中微生物群落的演替规律与理化指标的相互关系，对提高猪粪堆肥营养品质和加速堆肥进程具有重要的意义。  【方法】  以猪粪和玉米秸秆 (质量比6∶1) 混合物为堆肥原料，耐高温菌剂主要含Acinetobacter pittii、Bacillus subtilis subsp. Stercoris和Bacillus altitudinis。堆体设接种菌剂 (MI) 和未接种 (对照，CK) 两个处理。常规监测堆肥温度和理化指标值，于堆肥开始后第4、12、24和32天采集样品，以16S rRNA高通量测序技术研究堆肥细菌群落的变化。用堆肥第4、12、24和32天采集的新鲜样品制备浸提液，进行紫花苜蓿种子发芽试验。堆肥结束时，测定全氮、全磷和全钾含量，并探讨微生物菌剂对堆肥理化指标和细菌群落演替的影响。  【结果】  接种微生物菌剂可使堆肥高温期提前2天出现，并且能延长高温期2天。堆肥浸提液的促生试验发现，在堆肥24天后紫花苜蓿种子发芽指数 (GI) 大于80%，且MI对幼苗主根的促生能力大于CK (P < 0.05)。随着发酵过程的进行，堆体体积不断缩小，CK和MI中全钾 (TK) 和全磷 (TP) 含量一直呈增加趋势，在堆肥第32天，CK和MI的全磷含量分别为2.28%和2.63%，处理间差异显著 (P < 0.05)，而全钾含量分别为1.81%和1.86%，全氮含量分别为2.65%和2.63%，pH分别为8.72和8.78，处理间差异均不显著。在整个堆肥过程中，MI和CK的pH变化范围分别为8.40～8.95和8.61～8.93；CK和MI中总有机碳 (TOC) 的降解速率在堆肥的4～12和24～32天均表现为MI大于CK，CK和MI的碳氮比 (C/N) 分别为13.28和15.26，差异显著 (P < 0.05)。堆肥过程中在门水平上占据主导地位的细菌群落主要包括 Proteobacteria、Actinobacteria、Firmicutes和Bacteroidetes，在堆肥的高温期 (堆肥24天)，堆体CK和MI中Firmicutes的相对丰富度分别为17.4%和59.8%；在堆肥的升温期、高温期和腐熟期，优势门水平细菌群落Proteobacteria、Firmicutes和Actinobacteria依次演替，且MI堆体中细菌群落的相对丰度均大于CK。属水平优势细菌为Acinetobacter、Lysinibacillus、Solibacillus、Pseudomonas和Flavobacterium，添加微生物菌剂可使Acinetobacter的丰度在堆肥第4天增加21.41%，此外，添加复合微生物可使堆肥第12天的Shannon和Observed species指数增加。相关性分析表明，温度、全N (TN)、TP、TK、TOC及GI与堆体中细菌组成具有显著相关性，而pH和细菌的相关性不显著。  【结论】  在堆体内接种微生物菌剂可显著提高并维持堆肥过程中优势门、属细菌群落的丰度，进而促进堆体升温并延长高温时期，缩短堆肥腐熟周期，加快总有机碳的分解，最终提高堆肥产品中有效磷的含量。复合微生物菌剂在堆肥升温期起主要作用的为Acinetobacter pittii，高温期为Bacillus subtilis subsp. Stercoris和Bacillus altitudinis，我们建议筛选耐高温细菌时应集中在厚壁菌门的芽孢杆菌属。     

Cocomposting biosolids and municipal organic waste: effects of process management on stabilization and quality

The quality of compost made from the organic fraction of municipal organic waste (MOW), in terms of organic matter and nutrient concentrations, is inferior to that of compost from other feedstocks. The aim of this work was to improve the quality of MOW compost by means of cocomposting with biosolids (at ratios of 1:1, 2:1, and 3:1 MOW/biosolids) and vermicomposting. Vermicomposting (ground beds with worms) treatments were prepared from traditional pile material after 40 composting days; ground beds without worms were also included. Several parameters, including pH, electrical conductivity, carbon dioxide production, organic matter, total nitrogen, water-soluble carbon, nitrate, ammonium, and extractable phosphorus, were measured throughout the process. Organic matter in the products at 120 days ranged between 39 and 45%, whereas total nitrogen was between 1.7 and 2%. Considering these parameters, the quality of MOW and biosolids cocompost was better than that of MOW composted alone in a previous study (18% organic matter and 0.7% total nitrogen concentration). Extractable phosphorus was also greatly increased from 128 mg/kg in MOW compost to 542–722 mg/kg in the cocompost. Of the three MOW/biosolids ratios employed, only the 2:1 and 3:1 mixtures were adequate for composting and produced similar product qualities. However, the 2:1 mixture required more turnings and exhibited higher N losses. The improvement of quality by vermicomposting was limited. Compared to traditional piles, it did not affect concentrations of organic matter or total nitrogen. The direct action of worms, measured by comparing ground beds with and without worms, increased nitrate concentrations for mixtures 2:1 and 3:1 and extractable phosphorus concentrations for mixture 3:1.