不同有机物料对潮土微团粒分形特征和速效养分的影响

以河南省中低产区砂质潮土为对象,研究不同有机物料（豆秆、玉米秆、鸡粪和猪粪）还田处理对土壤微团粒结构分形和不同粒级有效养分质量分数的影响.结果表明：1）与不施有机物料处理相比,随有机物料添入量增加,0.1 ～0.053mm土壤粒级所占比例高于对照7％～13％,达到5％显著性差异水平;＜0.053 mm土壤粒级的质量分数相应小于对照处理.2）土壤分形维数在2.52～2.72之间,与0.1 ～0.053 mm土壤粒级质量分数存在极显著负相关,相关系数为-0.945;与＜0.053 mm土壤粒级存在极显著正相关,相关系数为0.981.随着从单施到混合配施的处理,有机物料改变微团粒结构的分配比例,分形维数变小.3）与对照相比,有机物料的加入均能使土壤以及各粒级的速效养分质量分数呈显著性增加.施入有机物料后,碱解氮、速效钾和速效磷的质量分数在0.1～0.053 mm土壤粒级中分别比对照提高了168％～528％、141％～1000％和16％ ～ 81％,在＜0.053 mm的粒级中分别比对照提高了13.4％ ～ 44％、17％ ～ 170％和21％ ～66％.土壤碱解氮质量分数表现为秸秆施用（73.1 mg/kg）＞秸秆与粪肥双倍混合施用（69.3 mg/kg）＞秸秆与粪肥单倍施用、猪粪施用（63.0 mg/kg）＞鸡粪施用（59 mg/kg）＞对照（49.9 mg/kg）;速效钾质量分数表现为豆秆施用（140 mg/kg）＞秸秆与粪肥双倍混合施用、玉米秆施（120 mg/kg）＞秸秆与粪肥单倍施用（86.5 mg/kg）＞粪肥施用（76.8 mg/kg）＞对照（56.5 mg/kg）;有效磷质量分数表现为玉米秸秆（40.9 mg/kg）＞粪肥处理、秸秆与粪肥混合处理（35.91 mg/kg）＞豆秆处理（30 mg/kg）＞对照（26.8 mg/kg）;土壤总养分质量分数表现为豆32和玉32处理（259 mg/kg）＞秸秆与粪肥倍量处理及豆16处理（225 mg/kg）＞玉16处理（210 mg/kg）＞秸秆与粪肥单倍量和猪8处理（191 mg/kg）＞鸡粪处理（173 mg/kg）＞猪4处理?     

Effects of straw and its biochar applications on the abundance and community structure of CO2-fixing bacteria in a sandy agricultural soil

Purpose

Crop straw and biochar application can potentially increase carbon sequestration and lead to changes in the microbial community in agricultural soils. Sequestration of CO₂ by autotrophic microorganisms is key to biogeochemical carbon cycling in soil ecosystems. The effects of straw and its biochar, derived from slow pyrolysis, on CO₂ fixation bacteria in sandy soils, remain unclear. Therefore, this study compared the response of abundance and community of CO₂ fixation bacteria to the two straw application methods in a sandy agricultural soil. The overall aim of the study was to achieve an efficient use of straw residues for the soil sustainablility.

Materials and methods

We investigated the soil organic carbon content and autotrophic bacteria over four consecutive years (2014–2018) in a field experiment, including the following four treatments: whole maize straw amendment (S), whole maize straw translated biochar amendment (B), half biochar and half straw amendment (BS), and control (CK) without straw or biochar amendment. The autotrophic bacterial abundance and community structure were measured using molecular methods of real-time PCR, terminal restriction fragment length polymorphisms (T-RFLP), and a clone library targeting the large subunit gene (cbbL) of ribulose-1,5-bisphosphate carboxylase/oxygenase.

Results and discussion

The results showed that the content of soil total organic carbon (TOC), dissolved organic carbon (DOC), and microbial biomass carbon (MBC) in B, S, and BS treatments was significantly increased compared with the CK treatment. Soil TOC and available potassium (AK) in the B treatment significantly increased by 15.4% and 23.3%, respectively, but soil bulk density, DOC, and MBC significantly decreased by 8.5%, 10.6%, and 14.5%, respectively, compared with the S treatment. The abundance of the cbbL gene as well as of the bacterial 16S rRNA gene increased significantly in straw or biochar application treatments as compared to the CK treatment. The B treatment, but not the BS treatment, significantly increased the cbbL gene abundance when compared to the S treatment. No significant differences were observed in the bacterial 16S rRNA gene abundance among the three straw or biochar applications. The application of straw biochar could increase the diversity of the autotrophic bacteria, which also altered the overall microbial composition. Physicochemical properties of the soil, such as soil pH, SOC, and bulk density, can help explain the shift in soil microbial composition observed in the study.

Conclusions

Taken together, our results suggest that straw biochar, rather than straw application, leads to an increase in the abundance and diversity of CO₂-fixing bacteria, which would be advantageous for soil autotrophic CO₂ fixation.

     

施硒对冬小麦产量及硒吸收转运的影响

为探明施硒(Se)对冬小麦产量及Se吸收转运的影响规律,采用盆栽试验,研究了北方石灰性潮土中5种施Se量对冬小麦产量、Se吸收及分布的影响。结果表明,随着施Se量的增加,冬小麦籽粒产量、成穗数和穗粒数均呈先增加后降低的趋势,其中,Se0.5、Se1处理的籽粒产量和各产量构成要素均高于Se0处理,最大值均出现在Se0.5处理。施Se显著增加了冬小麦各部位的Se含量、Se累积量以及植株总Se累积量;施Se增加了Se元素从颖壳向籽粒的迁移系数,降低了Se元素从地下部向地上部、茎叶向颖壳的迁移系数;施Se增加了Se在冬小麦籽粒中的占比,降低了Se在颖壳、茎叶中的占比。Se0.5、Se1较Se0处理,增加了冬小麦籽粒产量、籽粒Se含量、籽粒Se累积量及籽粒Se的占比。     

新型就仓干燥设备用于高水分小麦就仓干燥试验

采用组合式立体通风系统、空气加热器和粮仓绿色处理机组成的新型移动式就仓干燥设备对平均水分16．5％的800多吨小麦进行就仓干燥处理。在干燥过程中，对粮食水分、粮食温度、粮食微生物和干燥后小麦的品质进行测定分析。结果表明在通风干燥过程中，降水均匀，最终平均水分为12．9％，没有出现过干或过潮现象，粮温正常。由于粮仓绿色处理机所产生的臭氧的作用，霉茵总数呈下降趋势，没有霉变粮和霉味出现。干燥后小麦品质良好。与同品种晾晒干燥的小麦没有明显差异。     

不同类型大麦品种间杂交若干性状的相关分析

用简单相关分析方法,对不同类型大麦品种间杂交获得的12个世代的15个生育期和经济性状进行分析。验证了大麦幼穗分化开始比小麦早的观点,提出了拔节—孕穗是有效分蘖的关健时期。各经济性状间相关系数也得到分析,为大麦栽培和育种提供了依据。