温州蜜柑叶片黄化果园土壤及叶片的养分含量特征

弄清叶片黄化柑橘园土壤与叶片的养分含量特征,为改善柑橘园营养状况,提高柑橘产量和品质提供理论与技术支撑。通过对黄化和无黄化温州蜜柑园土壤、叶片的养分含量进行分析,研究影响温州蜜柑叶片黄化的关键因子。结果表明,温州蜜柑叶片的钙、镁、硼含量与SPAD值呈显著或极显著正相关,叶片黄化是由叶片中钙、镁、硼含量不足所造成的,属于综合缺素型,同时叶片中钾、铁、锰含量较高,叶片对钙、镁、硼的吸收与对钾、铁、锰的吸收之间存在相互拮抗的关系;土壤酸化是叶片黄化的主要驱动因子,pH值较低一方面降低了土壤中钙、镁、硼的有效性,另一方面,土壤中较高的铁、锰含量抑制了柑橘对钙、镁、硼的吸收,最终导致叶片因缺钙、缺镁、缺硼而出现黄化。喷施含钙、镁、硼的叶面肥料,防止土壤酸化是改善温州蜜柑叶片黄化的有效措施。     

Measurement of Nitrate Efflux from Roots and Its Relation to Nitrate Accumulation in Two Oilseed Rape Cultivars

Studies have reported significant differences in nitrate accumulation among genotypes within a crop species, but the reason for these differences is not clear. This study investigated nitrate (NO₃) efflux from roots of two oilseed rape cultivars (Brassica napus L. cvs. ZY821 and D89) and the relationship between nitrate efflux and plant nitrate accumulation. Nitrate efflux was estimated by measuring nitrate released from roots into nitrate-free nutrient solutions 58 days after sowing. The solutions were buffered with either 2.0 mM (n-morpholino) ethanesulfonic acid (MES) or 0.05 mM phosphate. Whole-plant and petiole nitrate accumulations were significantly greater for ZY821 compared to D89. Nitrate efflux varied diurnally, and the difference between cultivars was greater in the morning than in the afternoon. Data suggested that the relatively high pH of the phosphate-buffered solutions increased nitrate efflux rates from oilseed rape plants; therefore phosphate buffer should not be used when making direct determinations of nitrate efflux. Maximum cumulative nitrate efflux was 0.97 μmol g^?1 fresh-weight (FW) root for ZY821 and 1.9 μmol g^?1 FW root for D89. Maximum nitrate efflux rate was 0.084 μmol g^?1 FW min^?1 for ZY821 and 0.097 μmol g^?1 FW min^?1 for D89. These results indicated that between the two cultivars, ZY821 had the greatest petiole nitrate nitrogen concentration and the lowest total nitrate efflux. We suggest that cultivars with low nitrate efflux rates are able to translocate and store greater amounts of nitrate in aboveground plant organs, especially in petioles.     

下辽河平原不同水肥条件对玉米养分吸收与分配的影响

利用持续16年的长期田间试验与气象观测资料,研究了下辽河平原不同施肥与降水条件对玉米体内养分浓度、养分在籽实与秸秆中的分配比以及每形成单位籽实产量所收获养分量等的影响。结果表明,玉米体内养分浓度及养分在籽实与秸秆中的分配比例明显受施肥、降水及作物生长状况的影响。在平水年条件下,养分在籽实内累积的比例最高,其中N、P、K分别较偏旱或偏涝年景平均相对提高26．2％、33．3％和21．3％。同时,作物生长状况愈好,形成单位籽实产量所需养分量有减少的趋势,这些都说明良好的水肥条件有利作物生长,也有利于提高作物体内养分的转化利用效率。     

Application of the end-of-season stalk nitrate test for a high-yield maize production system in Northwestern China

Excessive nitrogen application has caused serious environmental pollution under high-yield maize system in China. Our objective was to evaluate critical stalk nitrate (NO₃^?) levels that support high yield (>13 Mgha^?1), but are not in excess. Optimal stalk NO₃^? concentration was determined by conducting seven nitrogen levels experiments in two high yield maize regions: Dongyang County (DY) and Wenshui County (WS). Optimal stalk NO₃^? concentration category range to obtain maximum yield in DY (sandy loam, higher accumulated temperature and solar radiation compared with WS) was 0.44–1.19, which similar to the criteria of US (0.70–2.0 g kg^?1). While for WS (loam soil, lower accumulated temperature and solar radiation compared with DY), optimal stalk NO₃^? concentration category range to obtain maximum yield was 1.95–4.15, greatly higher than the US criteria. These results suggested thatit is necessary to establish matching optimal stalk NO₃^? category ranges for different ecological regions in China.     

下辽河平原不同水肥条件对玉米养分吸收与分配的影响

利用持续16年的长期田间试验与气象观测资料，研究了下辽河平原不同施肥与降水条件对玉米体内养分浓度、养分在籽实与秸秆中的分配比以及每形成单位籽实产量所收获养分量等的影响。结果表明，玉米体内养分浓度及养分在籽实与秸秆中的分配比例明显受施肥、降水及作物生长状况的影响。在平水年条件下，养分在籽实内累积的比例最高，其中N、P、K分别较偏旱或偏涝年景平均相对提高26.2%、33.3%和21.3%。同时，作物生长状况愈好，形成单位籽实产量所需养分量有减少的趋势，这些都说明良好的水肥条件有利作物生长，也有利于提高作物体内养分的转化利用效率。     

Response to lime and P by several genetic sources of corn (Zsa mays L.) on a low pH and P soil in the greenhouse 1

The objective of this study was to investigate the response of 16 different genetic sources of corn (Zea mays L.) to lime and P application on a low pH and P Parsons silt loam soil in the greenhouse. A highly significant lime x P interaction was found for both dry matter production and P concentration. Phosphorus increased both dry matter production and P content of plant tissues with or without lime application. However, liming produced a detrimental effect when P was applied but no effect when no P was applied. Corn genetic sources showed a highly significant interaction with P treatment, but not with lime for both dry matter production and P concentration. The results suggest that improvement in corn growth could be achieved in a low P soil environment by genetic selection.     

Soil development on loess substrate in central Germany — results of a long‐term trial on soil formation§

In 1948, a model soil formation trial was started in Halle/Saale by Schmalfuß. Loess nearly free of soil organic matter (SOM) was used as substrate and the soil formation has been studied in dependence on the level of mineral P and N fertilization. The trial consists of 48 glazed clay cylinders (∅︁ 40 cm × 100 cm), which are open at the bottom. The cylinders are embedded in the ground and stand on a layer of gravel. The trial is divided in a section with constant P and graduated N application and a section with constant N and graduated P application respectively. In the first 30 years, yields increased strongest in the highest NP fertilizer treatment compared with the no‐N or no‐P fertilizer treatment. Afterwards yields in the different fertilization treatments remained nearly constant on the reached levels. Actually the mean shoot dry matter per year is 2.5 times higher in the highest fertilizer treatment as compared to the no‐N fertilizer treatment. The C_org content in the topsoil increased over 49 years in the highest fertilized treatment from 0.18% at the beginning of the trial to 1.94%. Compared to the treatments without N or P fertilization this corresponded, however, only to a 1.2 fold increase. With higher levels of fertilizer application, humus accumulation and biological activity increased relatively faster than the C_org content in the topsoil. Soil organic matter improved the nutrient availability (increase of cation exchange capacity, mobile P fractions). It is assumed that decalcification and the decrease in the C/N ratio will continue. The lower C_org and N_org contents and the lower cation exchange capacity in comparison with soils developed in‐situ near to the parent loess material suggest a still ongoing soil formation process in the trial.     

Soil quality and fertility in sustainable agriculture,with a contribution to the biological classification of agricultural soils

Soils and crops are particularly vulnerable to climate change and environmental stresses. In many agrosystems, soil biodiversity and ecosystem services provided by soils are under threat from a range of natural and human drivers. Agricultural soils are often subject to agronomic practices that disrupt soil trophic networks and make soils less productive in the long term. In this scenario, sustainable soil use aimed at improving plant/root status, growth and development plays a crucial role for enhancing the biological capacity of agricultural soils. This commentary paper is divided into the following four main sections: (i) the contentious nature of soil organic matter; (ii) soil biological quality/fertility; (iii) soil classification; and, (iv) which agricultural practices can be defined as sustainable? The published literature was analyzed within a holistic framework, with agrosystems considered as living systems where soil, vegetation, fauna and microorganisms co-evolve and are reciprocally influenced. Ultimately, this article will suggest a better stewardship of agricultural soils as a natural capital.     

Nitrogen Application Rate and the Concentration of Other Macronutrients in the Fruit and Leaves of Gold Kiwifruit

ABSTRACT

Gold kiwifruit (Actinidia chinensis Planch. var. chinensis ‘HORT16A’, marketed as ZESPRI?' ‘HORT16A’) is an important export crop for New Zealand. Nutrient management, including the application of nitrogen (N), for ‘HORT16A’ kiwifruit has mimicked strategies for the green (A. deliciosa ‘Hayward’) cultivar, however, physiological differences between Actinidia species necessitate the development of specific nutrient regimes for ‘HORT16A’ vines. In this trial, all nutrients, except N, were applied at levels comparable to commercial practice. The Control treatment received approximately 145 kg N ha/y, and was based on estimates of total N removed each year in the harvested fruit. The Zero-N treatment vines received all nutrients except N, and the High-N treatment received double the Control, approximately 295 kg N ha/y, for two consecutive seasons. The High-N treatment represents the upper limit of N application practices in commercial ‘HORT16A’ kiwifruit production. Zero-N fruit had higher calcium (Ca) and lower N concentration than High-N fruit in both seasons. Fruit potassium (K) and magnesium (Mg) concentrations were equivalent between these treatments in both seasons. Fruit phosphorus (P) concentration throughout the season was increased in the High-N treatment in both years. Fruit sizes were not different between treatments at final harvest in Year 1, being 130.5 ± 4.13 g, 125 ± 1.49 g, and 125 ± 3.29 g for the High, Control, and Zero-N vines, respectively. Larger fruit were harvested from the High-N vines (125 ± 4.69 g) in Year 2, than from either Control (113 ± 2.03 g) or Zero-N (118 ± 1.03 g) vines. Percent fruit dry matter (DM) content was higher in the Zero-N fruit (17.2 ± 0.06, 17.2 ± 0.06, and 16.8 ± 0.14 for Zero, Control, and High-N vines) at final harvest in Year 1. But values of fruit DM for all treatments were similar in Year 2 in spite of fruit size differences between treatments. Fruit DM for all treatments was slightly higher in Year 2 than in Year 1. Differences in fruit mineral concentration and fruit maturity at harvest may have contributed to increased incidence of low temperature breakdown (LTB) in the High-N fruit in Year 1. In Year 2, when fruit DM was higher in all treatments, yellow coloration was more developed. Total fruit N concentration was lower in Year 2 for all treatments than in Year 1, and LTB was minimal and not different between treatments.

Leaves from Zero-N vines had reduced N in both years compared with Control and High-N vines. In contrast, leaf Ca and Mg concentrations were reduced in High N-vines, compared with values recorded in Zero-N vines in both seasons. Leaf K concentrations were comparable between treatments in both seasons. Leaf sulfur (S) concentration was reduced under the High-N treatment, and leaf P levels were increased under the High-N treatment in both years.

These data demonstrate that N application influences the uptake and accumulation of other mineral elements in ‘HORT16A’ kiwifruit. In order to encourage desirable nutrient concentrations in both the fruit and leaves of ‘HORT16A’ kiwifruit, a reduction in N applied is suggested, and this would have little or no detrimental effect on vine performance over two seasons. Reduced N application will also reduce nitrate leaching which is estimated at 39 kg N ha/y under the Control treatment.     

Nutrient acquisition and nitrate reductase activity of mycorrhizal Retama sphaerocarpa L. seedlings afforested in an amended semiarid soil under two water regimes

Abstract. We studied the effect of inoculation with three arbuscular-mycorrhizal (AM) fungi ( Glomus intraradices Schenck & Smith, Glomus deserticola (Trappe, Bloss. & Menge) and Glomus mosseae ([Nicol & Gerd.] Gerd. & Trappe) and the addition of composted sewage sludge on root nitrate reductase (NR, EC 1.6.6.1.) activity, mycorrhizal colonization, plant growth and nutrient uptake in Retama sphaerocarpa L. seedlings afforested in a semiarid, degraded Mediterranean soil under well-watered and non-watered conditions. Six months after planting, the mycorrhizal inoculation and the irrigation of plants had a strong effect on the growth parameters. The effect on plant growth was a negative interaction between plant irrigation and mycorrhizal inoculation and a positive interaction between plant irrigation and composted sewage sludge addition. The latter treatment had a significant, but moderate, effect on the growth but conferred no additional benefit when combined with mycorrhizal inoculation. Mycorrhizal inoculation, composted sewage sludge and irrigation had a significant effect on NR activity in roots and on foliar nutrients. The irrigation significantly increased the positive effect of composted sewage sludge on NR activity and the concentrations of foliar N and K. The effect of mycorrhizal inoculation on NR activity did not depend on the water regime. The effectiveness of mycorrhizal inoculation on the establishment and growth of R. sphaerocarpa seedlings in these Mediterranean conditions was independent of water regime. The addition of composted sewage sludge was only effective when soil water was freely available. The combination of mycorrhizal inoculation and composted sewage sludge addition had no synergistic effect on plant growth.     

黄土高原刺槐林对土壤养分时空分布的影响

以不同树龄刺槐纯林林地和撂荒地作对比,研究了黄土高原刺槐人工林对土壤养分时空分布特征的影响。结果表明,刺槐林地土壤有机质、pH值、全氮、有效氮、有效磷、速效钾、交换性钙和交换性盐基总量随刺槐树龄增加无明确变化规律,土壤全磷和交换性镁含量则呈现波动性变化;刺槐林地土壤有机质、全氮、有效氮含量随土壤深度增加按幂函数衰减,有效磷含量有递减趋势,土壤全磷、速效钾、交换性钙、交换性镁和交换性盐基总量随土壤深度增加无明显变化规律,而土壤pH随深度呈波动性变化;与撂荒地相比,刺槐林地土壤有机质、全氮、有效氮、有效磷、速效钾、交换性钙、交换性镁含量及交换性盐基总量分别增加21.6%~96.8%,34.3%~160.1%,191.5%~238.4%,2.1%~24.1%,19.82%~92.71%,64.2%~80.0%,25.0%~46.5%和67.2%~89.5%,表明刺槐林对改善土壤养分状况具有重要作用。     

世界主要国家精准农业发展概况及对中国的发展建议

中国是一个农业生产和消费大国,同时也面临着投入产出比率相对较低、环境污染等一系列问题,尤其在国际形势变化、自然灾害频发的背景下,中国传统农业生产方式亟需转型升级。在人工智能、物联网、云平台等新兴技术的带动下,精准农业孕育而生,成为了全球农业实现绿色、高产的有效途径。该文瞄准世界精准农业发展较好的发达国家和地区,通过文献梳理和总结,凝练出政府引导、信息化建设、科技支撑、新型农民培育等发达国家和地区发展精准农业的成功经验。在此基础上,着眼于中国大田种植,分析中国发展精准农业的基础,从农田配套设施及信息化建设、农业信息获取、自动变量作业系统及装备等方面充分认识中国发展精准农业的薄弱环节。该文旨在厘清中国精准农业的发展方向,借鉴国际经验,提出中国精准农业今后的发展建议,如强化政府组织领导作用、加强基础设施和信息化建设、聚焦核心技术研发、培养新型农业人才、分区域试点示范。     

坡地土壤侵蚀与养分流失过程的研究

本文采用人工降雨室内试验,研究了坡地土壤侵蚀与有机质、全氮和有效磷养分的流失过程。坡度、雨强对其流失过程的影响;比较分析了裸露坡地及沙网覆盖两种处理的土壤侵蚀与养分流失过程。结果表明:随坡度,雨强增大,养分流失量也增加;试验小区覆盖纱网消除雨滴动能后,土壤养分流失量比裸露坡地减少60%左右;养分流失量与土壤流失量呈正相关,多数泥沙样中有效养分的含量高于土壤中养分含量,尤以有效磷更为显著。     

The problem of soil interpretation according to the WRB 2014 classification system in the context of anthropogenic transformations

Evaluation of soil transformations and degradation is important not only for agriculture, but also for fundamental research on identification of new features for classification. In 1999, new Lithuanian soil classification (LTDK-99) was developed by adopting the diagnostic principles of WRB 1998. Together with new knowledge, it highlighted some relevant soil research and classification problems. Not only new terms but also diagnostic features of several newly distinguished first-level soils groups are being discussed, especially for the identification of cambisols, planosols, arenosols, and regosols. Additionally, a group of stagnosols is suggested for inclusion into this classification. The presence of glaciogenic secondary clay minerals in Lithuanian cambisols does not imply unambiguous brownification involvement, neither any study shows cambisols having specific to brownification iron minerals. The intensively occurring lesive in these soils questions correctness of identification of cambisols additionally aggravated by strong and deep anthropogenization of the soil profiles within the territorial range. Complex glaciogenesis makes it difficult to identify Lithuanian planosols. WRB 2014 (update 2015) identifies planosols according to the pedogenesis in old, strongly weathered binomial deposits using examples mostly from South American, South and East African plateaus of the subtropical zone. The same classification assigns planosols identified in Lithuania to stagnosols, that is, to the soils characterized by binomial genesis and stagnification. The diagnostic features of arenosols and regosols are similar in both groups and are related to primitive pedogenesis. Difficulties in distinguishing between the two groups in Lithuania are strengthened by the intensive cultivation of the ecosystems in their territorial range. The existing problems in Lithuanian soil diagnostics underline the questions of soil classification in general, especially regarding the evolution tendencies in soil classification. The article draws attention to the soil diagnostic aspects like distribution and genesis of clay particles, genesis of territory, and anthropogenic transformation for the improvement of soil identification.     

Human-altered and human-transported (HAHT) soils in the U.S. soil classification system

ABSTRACT

Human-altered and human-transported (HAHT) soils are widespread across the globe and are concentrated near where people live and work. Although some of the HAHT soils are significant because they can be hazardous to human, animal, and plant health, most are not mapped or classified to the same extent as agricultural soils. The purpose of this article is to discuss the occurrence, types, and importance of HAHT soils and to document the historical and proposed classification of HAHT soils in Soil Taxonomy. There are two main forms of materials that define HAHT soils: human-altered soils formed in human-altered materials (HAM) from the soil surface to 50 cm (or to bedrock if shallower) or more and human-transported soils formed in human-transported materials (HTM) from the soil surface to 50 cm (or to bedrock if shallower) or more. The HAHT soils mainly occur in urban areas, transportation corridors, mined lands, landfills, filled shallow water, and agricultural areas on anthropogenic landforms. Hazards include danger from radioactivity, pollution, content of hazardous artifacts, or presence on unstable landforms that may fail during heavy rains or earthquakes. The HAHT soils are extensive, and their extent is growing. In the past, few HAHT soils were described or classified adequately because the U.S. Soil Taxonomy system was established for agricultural and other naturally occurring soils. However, HAHT soils are now being recognized and classified in many soil classification systems at very high levels. A new soil order is proposed for U.S. Soil Taxonomy that would include the most obvious profoundly and intentionally altered HAHT soils. A discussion and justification is given for an unofficial proposal. Input will be collected from international groups of scientists, and modifications of the unofficial proposal are expected. The long-term result of establishing a new soil order will be to enable proper classification, allocation, and mapping of HAHT soils worldwide.     

农用聚磷酸铵在土壤中的有效性研究进展及在农业上的应用

近年来,农用聚磷酸铵作为一种新型肥料逐渐进入我国化肥领域,常用作高浓度液体复合肥料的基础磷肥。聚磷酸铵pH值近中性,结晶温度低,具有螯合性、缓释性,有着很大发展空间。本文综述了聚磷酸铵在土壤中有效性(溶解性与移动性)的影响因素,重点分析水解速率、土壤矿物、土壤质地与水分对聚磷酸铵在土壤中的有效性,并分析聚磷酸铵在农业上的应用与发展前景。     

海南省芒果主产区土壤养分现状与果实矿质养分相关性评价与分析

研究海南省芒果主产区土壤养分丰缺及与果实矿质养分相关性,以期掌握芒果园土壤肥力现状,为科学、合理制定海南省芒果主产区的施肥策略奠基础。通过对海南省芒果主产区陵水、三亚、乐东、东方四市县芒果园0~20 cm、20~40cm土层采集的342个土壤样品和90个植物样品进行养分测定分析。研究发现,芒果园土壤pH均值为5.51,果园土壤呈酸性;果园有机质含量偏低,随土层加深而降低,四地土壤有机质含量在三级以下水平占各地土壤的比例分别为:陵水60%、三亚69%、乐东93%、东方100%;果园土壤全氮、碱解氮含量较低,基本在三级及以下水平,土壤速效钾、速效磷含量较高,大部分土壤在三级及以上水平范围,磷含量变异系数较大,分别为:0~20 cm土层为123.07%,20~40 cm土层为138.32%;芒果园土壤交换性钙含量较丰富,交换性镁含量较低,钙含量随土层加深而增加,镁则相反;芒果园微量元素含量比较丰富,随土层的加深有效铁、有效铜、有效锌含量减少,有效锰略微增加,有效硼基本不变;果园土壤养分含量与果实矿质元素含量的相关性较强,其中果实锰与土壤速效钾(相关系数0.990)、果实锰与土壤碱解氮(相关系数0.995)、果实锰与土壤有效锌(相关系数0.960)及土壤铜与果实铜(相关系数0.926)为显著的正相关,土壤有效磷与果实微量元素含量呈负相关关系,土壤有效铁与果实大量元素含量呈负相关,土壤速效钾和碱解氮与果实微量元素呈正相关。海南省芒果园土壤有机质、土壤氮(全氮、碱解氮)含量均较低,速效磷和速效钾含量为中上水平,交换性镁含量较低,果园土壤微量元素较丰富。建议生产中以基肥为主,增施有机肥,适当配施锰等微量元素,可以喷施少量叶面肥补充微量元素。在施肥时应平衡施肥,合理用量。