甘肃陇南粮油作物合理种植比例的气候分析

通过对夏粮、秋粮和油料作物降水的增减产效应分析，找出了降水对产量影响的关键时段，提出了作物合理种植比例方案。     

株洲市白马乡土壤和农作物重金属污染评价

本文对株洲市白马乡土壤及其农作物中重金属含量进行了调查并对其污染进行了评价。结果表明:该乡土壤和作物均受到了不同程度的重金属污染,土壤达不到土壤环境质量二级标准要求,作物达不到食品卫生标准要求,土壤重金属污染因子主要为Cd,作物中主要重金属污染因子为Cd、Pb。附近清水塘工业区排放的大气污染物重金属尘是造成白马乡土壤和作物重金属污染的主要因素。不同测点土壤和作物污染程度差别极大,主要和各测点与最大重金属尘污染源距离的远近、方位及风向有关。     

植物化感作用表现形式及其开发应用研究

综述了作物自毒现象、作物间他感作用以及作物与杂草间他感互作的研究进展,指出化感作用在克服连作障碍、构建高效间套复合群体、防除病虫草害和生物调控方面的应用潜力。     

右江河谷一年三熟的气候可行性研究

从气候角度论证右江河谷双季稻作区改制“春玉米＋中稻＋秋冬玉米”一年三熟种植的可行性,并提出实施一年三熟改制的相应技术措施。     

Critical review of the impact of cover crops on soil properties

Grasses as well as leguminous and non-leguminous broadleaves are the major categories of commonly grown cover crops worldwide. This review focuses on the contribution of cover crops to soil properties. The review first considers the single and mixed cover crops and shows that grass species are desirable for their decay and ability to provide substantial soil cover, broadleaf species are used for their quick decomposition and capacity of releasing residues into the soil, while the leguminous species are used for their ability to fix atmospheric nitrogen. Secondly, the impacts of cover crops on soil health are reviewed. Integrating cover crops into conventional cropping systems may reduce soil bulk density, improve soil structure and hydraulic properties to facilitate increased water infiltration and storage. Crop residue additions from cover crops may enhance soil organic C and N accretion as well as increase availability of P, K, Ca, Fe and Mg in some soil types under certain climatic conditions. Further, cover crops may provide a better condition for microbial activity, abundance, and diversity. Finally, the review shows that through proper management, cover crops may be utilized as an essential component of soil conservation practices for enhanced soil health. Still, further investigation is necessary to determine cover crop effects in additional cropping systems and climatic zones as well as the long-term effects of cover crops on soil properties, subsequent crop yield, and overall cropping system profitability. This review is an important source of information for crop growers, crop management institutions, universities, and crop consultants for sustainable agricultural production.     

Agronomy and Physiology of Tropical Cover Crops

Cover crops are important components of a sustainable crop production system. They can be planted with plantation crops such as cacao, coffee, banana, rubber, and oil palm or in rotation with cash crops. Their use in a cropping system is mainly beneficial for soil and water conservation, recycling of nutrients, control of pests and improved microbiological activities. However, beneficial effects depend on the selection of appropriate cover crops and their management. Hence, understanding their agronomy and physiology is fundamental for their use in sustainable cropping systems. Growth and development of a crop (physiological aspects) is determined genetically as well as influenced by environmental variables. This information can be useful in improving production of these crops and, consequently, their incorporation in farming systems, wherever it is possible. There are hundreds of tropical cover crops and, therefore, it is not possible to include all of them in one article. Hence, selected cereals and legumes are included.     

Traditional Food Crops and Their Role in Food and Nutritional Security in Kenya

In Kenya, traditional food crops play an important role in food and nutritional security, especially in the dry parts of Kenya. This study set out to document the most important traditional food crops in Kenya and highlight their production levels, production ecologies, as well as their nutritional value. The findings reveal that the relative importance of traditional food crops differs from one area to another and, while some are produced for subsistence use; others, like sweet potatoes, are grown for commercial purposes. Despite their potential contribution to food and nutritional security, production of traditional food crops is far below that of maize (the main staple food in Kenya). The authors recommend rigorous promotion to increase their production and consumption, since traditional food crops are grown in the arid and semi-arid parts of the country where maize does not perform as well.     

Cover crop growth and impact on N leaching as affected by pre‐ and postharvest sowing and time of incorporation

In Northern Europe, cover crops are traditionally established before spring crops by undersowing, but some cover crops might also have an effect if preharvest sown before spring crops and even winter crops. The effects of cover crop sowing date, sowing technique and succeeding main crop on biomass production, N uptake, nitrate leaching and soil inorganic N were tested in lysimeters and in the field. Cruciferous cover crops (oil radish, white mustard) were sown preharvest by broadcasting into winter wheat in July and were allowed to grow until a following winter wheat was established in September. Other preharvest cover crops were left in place until late autumn. For comparison, the same cruciferous cover crops were established postharvest after light harrowing. Perennial ryegrass undersown in spring barley was also included. Aboveground N uptake in preharvest cover crops amounted to a maximum of 24 kg N/ha in September before sowing winter wheat. When left until late autumn, preharvest oil radish took up a maximum of 66 kg N/ha, and ryegrass and postharvest cover crops 35 kg N/ha. Preharvest establishment of cruciferous cover crops before a spring‐sown crop thus seems promising. The soil was depleted of inorganic N to the same extent in late autumn irrespective of cover crop type, sowing time and technique within winter wheat or spring barley. However, the reduction in nitrate leaching of preharvest cover crops incorporated after 2 months and followed by winter wheat was only half of that achieved by cover crops left until late autumn or spring.     

Role of Cover Crops in Improving Soil and Row Crop Productivity

Abstract

Cover crops play an important role in improving productivity of subsequent row crops by improving soil physical, chemical, and biological properties. The objective of this article is to review recent advances in cover crops practice, in the context of potential benefits and drawbacks for annual crop production and sustained soil quality. Desirable attributes of a cover crop are the ability to establish rapidly under less than ideal conditions, provide sufficient dry matter or soil cover, fix atmospheric nitrogen (N), establish a deep root system to facilitate nutrient uptake from lower soil depths, produce organic matter with low‐residue carbon/nitrogen (C/N) ratio, and absence of phytoxic or allelopathic effects on subsequent crops. Cover crops can be leguminous or nonleguminous. Leguminous cover crops provide a substantial amount of biologically fixed N to the primary crop, as well as ease of decomposition due to their low C/N ratio. Legume cover crops also possess a strong ability to absorb low available nutrients in the soil profile and can help in increasing concentration of plant nutrients in the surface layers of soil. Some nonleguminous cover crops having high N scavenger capacity compared with leguminous crops and sometimes, the growth of these scavenging grass cover crops is limited by N deficiency, growing grass/legume mixtures appears to be the best strategy in obtaining maximum benefits from cover crops.     

Biofortification of Trace Elements in Food Crops for Human Health

Micronutrient deficiencies have been reported in food crops worldwide. Several macro- and micronutrients are essential for human health. However, among these elements, the trace elements zinc (Zn), iron (Fe), iodine (I), selenium (Se), and cobalt (Co) are limiting in the diets of much of the world's population. According to United Nations estimates, about 1 billion people, especially woman and children, are suffering from malnutrition of trace elements, especially in Africa, Asia, and South America. Improving bioavailability of these elements in food crops is an important strategy to overcome trace-element deficiencies in food crops and improving human health. Genetic variability in micronutrient contents in the grain of crops such as rice, corn, wheat, barley, soybean, and dry bean is widely reported in the literature. Hence, use of genetic variability among crop species and genotypes within species is an important strategy to achieve biofortification of grain of staple food crops. Other practices that can be adopted to improve bioavailability of essential elements in food crops are adopting appropriate agronomic practices, such as adequate rate, effective sources, and effective methods of fertilizer application. Use of biotechnology is also feasible to biofortification of staple food crops. Planting indigenous and traditional food crop species with high nutritive value is another important strategy to improve trace elements in human food.     

Arbuscular mycorrhizal fungi-mediated nitrogen transfer from vineyard cover crops to grapevines

Cover crops are often planted in between vineyard rows to reduce soil erosion, increase soil fertility, and improve soil structure. Roots of both grapevines and cover crops form mutualistic symbioses with arbuscular mycorrhizal (AM) fungi, and may be interconnected by AM hyphae. To study nutrient transfer from cover crops to grapevines through AM fungal links, we grew grapevines and cover crops in specially designed containers in the greenhouse that restricted their root systems to separate compartments, but allowed AM fungi to colonize both root systems. Leaves of two cover crops, a grass (Bromus hordeaceus) and a legume (Medicago polymorpha), were labeled with 99 atom% ¹⁵N solution for 24 h. Grapevine leaves were analyzed for ¹⁵N content 2, 5, and 10 days after labeling. Our results showed evidence of AM fungi-mediated ¹⁵N transfer from cover crops to grapevines 5 and 10 days after labeling. N transfer was significantly greater from the grass to the grapevine than from the legume to the grapevine. Possible reasons for the differences between the two cover crops include lower ¹⁵N enrichment in legume roots, higher biomass of grass roots, and/or differences in AM fungal community composition. Further studies are needed to investigate N transfer from grapevines to cover crops and to determine net N transfer between the two crops throughout their growing seasons, in order to understand the significance of AM fungi-mediated interplant nutrient transfers in the field.     

Pseudocereals and millets: the lost crops of Kashmir

The aim of present study was to know about past cultivation of pseudocereals and millets in Kashmir province of Indian state of Jammu and Kashmir. These crops which were cultivated throughout Kashmir in plains as well as in hilly areas are buckwheat species, Fagopyrum esculentum and Fagopyrum tataricum; amaranth and minor millets, Setaria italica and Panicum miliaceum. In Kashmir these are now forgotten crops. Few plants of amaranth (Amaranthus caudatus) are still grown in almost every kitchen garden in Kashmir. The crop is however not cultivated commercially neither in Kashmir nor in Ladakh or Jammu provinces of the state. Our study has revealed that cultivation of all these crops has been abandoned some five or six decades back throughout Kashmir excepting in few farflung hilly areas in north Kashmir. Currently these crops are also cultivated in Ladakh, but here also their cultivation is dwindling rapidly. The reasons as to why farmers have abandoned these crops and are increasingly losing interest in these biological assets in the areas of their present cultivation have been discussed. There is a need to rescue these threatened crops which have many advantages besides, being nowadays categorized as quality health foods. During our survey in Ladakh province we have collected 30 germplasm accessions of these crops from various locations. These have been deposited in National Seed Gene Bank at NBPGR, New Delhi for conservation and evaluation. The improvement and revival of these lost crops has the potential to diversify agriculture, food system and income of the poor farmers and have the ability to ensure food security and livelihood of the people in this Himalayan state under future adverse climatic conditions.     

黄淮海平原农业战略区划与布局研究

许多学者对黄淮海平原农业区划进行过大量研究, 但定量化的研究尚不多见。本文在对黄淮海平原301县(区)大量调查的基础上, 综合黄淮海平原的自然资源条件、主要农作物产量及农业总产值等指标, 通过定性与定量结合, 对其进行了农业总体战略区划与布局。将黄淮海平原区划为高产区、中低产区两大类产区, 高产区又细分为粮食优势产区、棉花优势产区、油料优势产区、粮棉优势产区、粮油优势产区、棉油优势产区、粮油棉优势产区7个优势产区。在此基础上对各小区进行了具体布局研究, 这对整个黄淮海平原农业发展具有战略指导及理论意义。     

Reduced tillage in north-west Europe—A review

The main features of the climate and soils of the main crop production areas of different countries in north-west Europe are outlined, and the main crops grown are summarised. The need for tillage is considered; provided that suitable conditions exist for germination, root growth is most likely to be influenced by mechanical impedance and aeration. Traditional tillage may not always be necessary and may hinder timely sowing of crops. Shallow tillage can facilitate planting a larger area of crops closer to the optimum dates in autumn and in spring, which also saves energy and labour.Research experience with reduced tillage over the last 20–25 years is reviewed. Shallow tillage has been as good as mouldboard ploughing at the traditional depth in most countries on a wide range of soil types, if weed control was satisfactory. Direct drilling has often proved satisfactory in the absence of crop residues for autumn sown crops (wheat, barley, oil-seed rape and beans) where drainage (and therefore soil aeration) was not limiting. Direct drilling has not generally been successful for spring sown crops. Direct drilling is inappropriate for root crops, but strip tillage for sugar beet may become practicable. Some research on soil conditions associated with these experiments is considered.Crop residues are a major constraint to shallow tillage or direct drilling of autumn sown crops. The limitations of reduced tillage due to inadequate weed control, wheel-traffic damage and unsatisfactory drainage are reviewed. The need for occasional deep loosening is also discussed. Where the amount of residues is small, much tillage may be unnecessary, except to relieve compaction by wheels; bed systems or wide-span gantries to avoid wheel damage could become practical developments for some crops.     

鄂西南山地垂直气候生境地带

本文分析了鄂西南山地光、温、水等主要气候因子随海拔高度变化的规律。在此基础上结合各种作物和林木的生物学特性，估算出它们在不同高度的生物生产量，进而分析得出山区各种作物和林木的适生地带。     

Cover crop potential of winter oilseed crops in the Northern U.S. Corn Belt

ABSTRACT

Winter camelina [WC, Camelina sativa (L.) Crantz] and field pennycress (FP, Thlaspi arvense L.) are emerging oilseed crops in corn–soybean rotations, but little is known about their cover crop potential. A 2-year study was conducted in Minnesota, USA to evaluate the effect of winter oilseed crops on nitrogen (N) use, growth and yield of corn and soybean. Treatments included WC, FP, winter rye (WR, Secale cereale L.), and a no cover crop (NC) control. Oilseed crops produced 40–50% less spring biomass and accumulated less N compared to WR. The tissue-N of WC and FP was 39.0% and 6.6% higher than WR, respectively. The C:N ratio of cover crops was lower than 20:1, suggesting rapid decomposition. Compared with NC, cover crops lowered soil nitrate before major crops planting, but the post-harvest N profile following corn and soybean was not affected. Compared with NC, cover crops significantly decreased corn yield, with 8.7%, 9.5% and 9.8% reduction following WC, FP and WR, respectively. Cover crops did not affect growth, yield and N uptake of soybean. Oilseed crops showed potential to improve N cycling in the rotation, but more research of their impact on major crops is needed.     

施肥对蔬菜累积硝酸盐影响的研究进展

施肥是提高蔬菜产量的重要措施,然而不合理施肥会引起蔬菜硝酸盐的积累。本文主要对近年来国内外有关氮、磷、钾和有机肥料等的施用对蔬菜硝酸盐积累的影响进行了讨论并对今后的研究提出了一些建议。     

不同作物对铬毒害耐性的研究

铬是一种重要的环境污染物,土壤中过量的铬将抑制作物生长,降低产量;作物中累积的铬又通过食物链富集于人体。因此,铬对粮食、蔬菜作物生长的影响,以及铬在农作物中的累积已为许多研究者所关注。但不同作物对铬毒害耐性的研究尚少见报道。本文采用4种粮食作物(6个品种)、5种牧草和7种蔬菜作物(10个品种)为对象,分析比较作物耐铬性的差异,并从生理生化方面探讨作物耐铬性的实质,以探讨重金属铬的毒害机理。     

Surface activity of soil ecosystem engineers and soil structure in contrasted land use systems of Colombia

This study describes the impact of the conversion of native Colombian savannahs into crops and pastures on: (1) the quantity and diversity of the bio-structures produced by soil ecosystem engineers and (2) soil structure. Bio-structure diversity decreased in all agroecosystems (12 types in the savannah, four to six in pastures and three in crops). Bio-structures were mostly earthworm casts in native savannah and pastures, and ant mounds in crops. Compared with the savannah (750 cm³ m^–2), their volume increased in the old pasture (+48%) and decreased in recent pasture and crops (–65% to –97%). Soil structure was similar to savannah soil in the older pasture, but was sharply affected in annual crops. In contrast to crops, pastures appear to sustain soil structure and are also suitable for engineering activity.     

Cover crop identity determines root fungal community and arbuscular mycorrhiza colonization in following main crops

Cover crops (CC) can promote nutrient retention and recycling for main crops yet may also promote soilborne pathogens or suppress beneficial root symbionts such as arbuscular mycorrhizal fungi (AMF). We investigated how root fungal communities of main crop are affected by preceding CC monocultures and mixtures and by main crop identity. We expected that AMF abundance and diversity in main crops are promoted by AM-host CC, and suppressed by non-AM-host CC, and that mixtures of CC species can promote beneficial and suppress pathogenic root fungi. Our full-factorial field experiment comprised crop rotation in sand soil with different CC treatments (monocultures of radish [AM non-host], ryegrass, clover, vetch [AM hosts], mixtures of radish + vetch, ryegrass + clover and fallow) and two main crops (oat and endive). At peak crop growth, we investigated the root fungal communities in the main crops using microscopy and high throughput sequencing (Illumina MiSeq). Cover crop identity was of prime importance and CC legacy overruled main crop identity in determining root fungal communities in main crops. Compared with fallow, CC with ryegrass increased AMF colonization and richness in both main crops and of non-AMF in oat. Legacies of ryegrass, ryegrass + clover and vetch resulted in distinct root fungal communities in the main crops, while the legacy of CC with radish were similar to the legacy of fallow. Root fungal community in crops after clover had highest abundance of representative fungal pathogens in contrast with the other CC treatments that resulted in fungal communities where pathogens were scarce. Oppositely to expected, CC mixtures did not enhance fungal symbionts or suppressed pathogens. Overall, fungal communities in roots of the main crops in our field experiment were determined by the preceding CC species in monoculture, rather than by the CC AMF preference or functional group. This research highlights that the choice of CC determines the root fungal community in main crop which may influence crop quality.