Tillage and drainage impact on soil quality: I. Aggregate stability, carbon and nitrogen pools

Effects of two tillage treatments, tillage (T) with chisel plough and no-till (NT), were studied under un-drained and drained soil conditions. Soil physical properties measured were bulk density (ρ_b), total porosity (ƒ_t), water stable aggregates (WSA), geometric mean diameter (GMD), mean weight diameter (MWD), organic carbon (OC) and total N concentrations in different aggregate size fractions, and total OC and N pools. The experiment was established in 1994 on a poorly drained Crosby silt loam soil (fine mixed, mesic, Aeric Ochraqualf) near Columbus, Ohio. In 2007, soil samples were collected (0–10, 10–20, and 20–30 cm) from all treatments and separated into six aggregate size classes for assessing proportions of macro (5–8, 2–5, 1–2, 0.5–1, 0.25–0.5) and micro (<0.25 mm) aggregates by wet sieving. Tillage treatments significantly (P ≤ 0.05) influenced WSA, MWD, and GMD. Higher total WSA (78.53 vs. 58.27%), GMD (0.99 vs. 0.68 mm), and MWD (2.23 vs. 0.99 mm) were observed for 0–10 cm depth for NT than T treatments. Relative proportion of macro-aggregates (>0.25-mm) was also more in NT than T treatment for un-drained plots. Conversely, micro-aggregates (<0.25-mm) were more in T plots for both drained and un-drained treatments. The WSA, MWD and GMD decreased with increase in soil depth. The OC concentration was significantly higher (P ≤ 0.05) in NT for un-drained (P ≤ 0.01) treatment for all soil depths. Within macro-aggregates, the maximum OC concentrations of 1.91 and 1.75 g kg⁻¹ in 1–2 mm size fraction were observed in NT for un-drained and drained treatments, respectively. Tillage treatments significantly (P < 0.01) affected bulk density (ρ_b), and total porosity (f_t) for all soil depths, whereas tillage × drainage interaction was significant (P < 0.01) for 10–20 and 20–30 cm depths. Soil ρ_b was negatively correlated (r = −0.47; n = 12) with OC concentration. Tillage treatments significantly affected (P ≤ 0.05) OC pools at 10–20 cm depth; whereas drainage, and tillage × drainage significantly (P ≤ 0.05) influenced OC pools for 0–10 cm soil layer. The OC pool in 0–10 cm layer was 31.8 Mg ha⁻¹ for NT compared with 25.9 Mg kg⁻¹ for T for un-drained treatment. In comparison, the OC pool was 23.1 Mg ha⁻¹ for NT compared with 25.2 Mg ha⁻¹ for T for the drained plots. In general, the OC pool was higher in NT system, coupled with un-drained treatment than in drained T plots. The data indicate the importance of NT in improving the OC pool.     

The effectiveness of airborne LiDAR data in the recognition of channel-bed morphology

High-resolution topographic data have the potential to differentiate the main morphological features of a landscape. This paper analyses the capability of airborne LiDAR-derived data in the recognition of channel-bed morphology. For the purpose of this study, 0.5 m and 1 m resolution Digital Terrain Models (DTMs) were derived from the last pulse LiDAR data obtained by filtering the vegetation points. The analysis was carried out both at 1-D scale, i.e. along the longitudinal channel profile, and at 2-D scale, taking into account the whole extent of the channel bed. The 1-D approach analyzed the residuals of elevations orthogonal to the regression line drawn along the channel profile and the standard deviation of local slope. The 2-D analysis was based on two roughness indexes, consisting on the local variability of the elevation and slope of the channel bed. The study was conducted in a headwater catchment located in the Eastern Italian Alps. The results suggested a good capability of LiDAR data in the recognition of river morphology giving the potential to distinguish the riffle-pool and step-pool reaches.     

Quantifying macroinvertebrate taxon richness and abundance in open and forested pool complexes in the Sutherland Flows

1. The aquatic macroinvertebrates of two pool complexes, one open and one forested, in the Sutherland Flows containing temporary, drought sensitive and permanent pools were sampled to establish the most economical sampling for future investigation into the effects of afforestation. 2. Given the variation in pool type and size within each complex, (a) an estimate of the average number of taxa per pool of each type was needed to compare pools of different types, (b) the total number of taxa found in each pool type was needed to allow comparison between sites. 3. Thirty specimens from each pool established the average number of taxa per pool and showed that permanent pools had a higher taxon richness than temporary pools. 4. Four hundred and fifty specimens (and therefore 15 pools with 30 specimens each) were needed to give an estimate of the total number of taxa per pool type. However, the number of samples in some categories was insufficient to allow comparisons to be made between sites and rarefaction was used to make baseline comparisons. 5. Rarefaction suggests that at both sites the permanent pools had highest taxon richness. Rarefaction also indicated there may be slightly higher total invertebrate taxon richness in each pool type at the forested site. Copyright © 1999 John Wiley & Sons, Ltd.     

淡水鱼池生态系统的悬浮物结构及有机碳库储量

于2002年6月至2003年3月对辽宁省碧流河水库4个淡水池塘(鲢、鳙亲鱼池)的悬浮物结构及有机碳库储量进行了研究。结果表明:各池塘颗粒悬浮物重量(TS)为18.14~62.92 mg/L,平均为(37.53±22.02)mg/L,灰分含量平均为33%;浮游生物干重(PZ)占TS的16.81%~30.65%,平均为25.05%;浮游植物干重(DWP)为4.62~12.33 mg/L,平均为8.15 mg/L;浮游动物干重(DW Z)为0.08~0.81 mg/L,平均为0.50 mg/L;溶解有机碳(DOC)和颗粒有机碳(POC)的库储量分别为(11.32±3.66)mg/L和(8.75±4.28)mg/L。TOC∶DOC∶POC=1∶0.56∶0.44;池塘POC中细菌和腐质碳(BDC)、浮游植物碳(PC)、浮游动物碳(ZC)的比例为26.45∶16.30∶1;在浮游生物碳(PZC)中,浮游植物碳占94.22%,起主导作用。     

对虾封闭式淡化养殖试验

在虾池周围打机井，挖平塘，用地下水作水源，实行对虾封闭式淡化养殖，切断了海水污染源。结果；１１００亩虾池亩产对虾１０５ｋｇ，规格１２ｃｍ，尾重２０ｇ。共产对虾１１２ｔ，产值８６９万元，投入产出比１：２．９。专家鉴定认为，技术水平属国内先进。     

Long-term fertilization effects on carbon pools and carbon management index of loamy soil under grass–forage legumes mixture in semi-arid environment

ABSTRACT

Soil organic carbon (SOC) is a key component for sustaining crop production. A field experiment was conducted during 2004–2018 to assess the changes in soil carbon fractions under different fertilization practices in grass-legumes mixture. The result indicates that application of farmyard manure (FYM) at 80 Mg ha^–1 has increased SOC concentration leading to carbon sequestration rate of 4.2 Mg ha^–1 year^–1. Further, it has increased the proportion of labile carbon in the total SOC and have accumulated 126, 60, 83 and 95% higher very labile, labile, less labile and non-labile C stock than that of control plot, respectively, in top 30 cm soil layer. Inorganic fertilization and FYM 20 Mg ha^–1 influenced SOC concentration, SOC stock and C sequestration rate similarly. The highest carbon management index (264) was found in the treatment receiving FYM 80 Mg ha^–1 and it was positively correlated with SOC (r = 0.84**). The sensitivity index of the SOC varied from 26 to 152% and the differences were greatest in FYM treatments. The result indicates that grass-legumes mixture build-up the SOC in long term and the addition of FYM further increases it.     

镉在超富集植物滇苦菜叶子中细胞耐受性,镉的积累和分配研究

Climate change and elevated atmospheric CO2 should affect the dynamics of soil organic carbon (SOC). SOC dynamics under uncertain patterns of climate warming and elevated atmospheric CO2 as well as with different soil erosion extents at Nelson Farm during 1998-2100 were simulated using stochastic modelling. Results based on numerous simulations showed that SOC decreased with elevated atmospheric temperature but increased with atmospheric CO2 concentration. Therefore, there was a counteract effect on SOC dynamics between climate warming and elevated CO2 . For different soil erosion extents, warming 1 C and elevated atmospheric CO2 resulted in SOC increase at least 15%, while warming 5 C and elevated CO2 resulted in SOC decrease more than 29%. SOC predictions with uncertainty assessment were conducted for different scenarios of soil erosion, climate change, and elevated CO2 . Statistically, SOC decreased linearly with the probability. SOC also decreased with time and the degree of soil erosion. For example, in 2100 with a probability of 50%, SOC was 1 617, 1 167, and 892 g m 2 , respectively, for no, minimum, and maximum soil erosion. Under climate warming 5 C and elevated CO2 , the soil carbon pools became a carbon source to the atmosphere (P > 95%). The results suggested that stochastic modelling could be a useful tool to predict future SOC dynamics under uncertain climate change and elevated CO2 .     

LONG‐TERM MANURING AND FERTILIZER EFFECTS ON DEPLETION OF SOIL ORGANIC CARBON STOCKS UNDER PEARL MILLET‐CLUSTER BEAN‐CASTOR ROTATION IN WESTERN INDIA

Soil organic carbon (SOC) pools are important for maintaining soil productivity and reducing the net CO₂ loading of the atmosphere. An 18‐year old long‐term field experiment involving pearl millet‐cluster bean‐castor sequence was conducted on an Entisol in western India to examine the effects of chemical fertilizers and manuring on carbon pools in relation to crop productivity and C sequestration. The data showed that even the addition of 33.5 Mg ha⁻¹ C inputs through crop residues as well as farm yard manure could not compensate the SOC depletion by oxidation and resulted in the net loss of 4.4 Mg C ha⁻¹ in 18 years. The loss of SOC stock in the control was 12 Mg C ha⁻¹. Conjunctive use of chemical fertilizers along with farm yard manure produced higher agronomic yields and reduced the rate of SOC depletion. The higher average seed yields of pearl millet (809 kg ha⁻¹), cluster bean (576), and castor (827) over six cropping seasons were obtained through integrated use of fertilizers and manure. For every Mg increase in profile SOC stock, there was an overall increase of 0.46 Mg of crop yield, comprising increase in individual yield of pearl millet (0.17 Mg ha⁻¹ y⁻¹ Mg⁻¹ SOC), cluster bean (0.14) and castor (0.15). The magnitude of SOC build up was proportional to the C inputs. Carbon pools were significantly correlated with SOC, which increased with application of organic amendments. Threshold C input of 3.3 Mg C ha⁻¹ y⁻¹ was needed to maintain the SOC stock even at the low antecedent level. Copyright © 2011 John Wiley & Sons, Ltd.     

甘蔗抗褐锈病新基因抗感病池构建及SSR多态性引物筛选

由黑顶柄锈菌(Puccinia melanocephala H. Sydow ＆ P. Sydow)引起的甘蔗褐锈病是危害中国甘蔗生产的主要病害之一。为了鉴定和发掘抗褐锈病新基因,防止褐锈病爆发流行和保证甘蔗安全生产,本研究以杂交组合‘粤糖03-393’× ‘ROC 24’抗感分离真实性F₁代群体为材料,构建抗感基因池,合成449对引物对抗感亲本及抗感基因池进行抗、感连锁SSR分子标记筛选。结果表明,25对引物在抗感亲本间有多态性,其中4对引物(SMC236CG、SCESSR0928、SCESSR0636、SCESSR2551)在抗感亲本及抗感池间有多态性,初步判定这4个SSR标记在染色体上的位点可能与抗褐锈病新基因存在连锁关系。研究结果为后续开展抗褐锈病新基因定位、为中国甘蔗褐锈病防控及抗病育种奠定了良好的基础。     

有机污染水灌溉对土壤有机碳状况的影响

以长期采用有机污染型水灌溉的陕西交口灌区的农田土壤作为研究对象,并以气候条件、土壤条件以及耕作制度基本一致,长期采用未污染的地下水灌溉的农田土壤作为对照,分别测定土壤剖面上总有机碳含量、有机碳组成等指标,结合第二次全国土壤普查资料,分析长期采用有机污染水灌溉对土壤有机碳累积速率及有机碳密度的影响,探讨关中土壤"环境碳容量"水平及提升土壤有机碳潜力的途径。结果表明:长期采用有机污染水灌溉,土壤有机碳主要在耕层(0~20 cm)极显著地增加,且增加部分主要是活性有机碳组分,其累积速率是对照灌区的近3倍,非活性有机碳处于相对平衡状态。土壤有机碳的剖面分布发生了明显的分化现象,活性有机碳的变化比总有机碳的变化更为显著。有机污染水灌溉的土壤有机碳密度显著高于对照土壤,尤其在0~40 cm范围内其差异达极显著水平。结果证实渭河水中富含的有机污染物提升了灌溉农田土壤有机碳贮量,关中地区农田土壤环境碳容量仍未达到饱和水平,通过外源有机碳的输入,仍然有增加土壤有机碳含量的可能。