Soil Fertility Degradation Research Articles

Incorporation of Leguminous Cover Crops in Smallholder Cassava-Based Production System in Western Tanzania

Small-scale crop production in many parts of Tanzania is constrained by many problems among which soil fertility degradation is a major problem. Over 80% of cassava (Manihot esculenta) production in Tanzania is done by the small-scale farmers who continuously cultivate their fields, but use limited inputs to restore depleted plant nutrients. The objective of this study was to examine the best legume species that could be incorporated in cassava (Manihot esculenta) production systems under farmers’ conditions and result in increase in soil fertility and crop yields. Mucuna pruriens and Canavalia ensiformis were either incorporated with cassava (Manihot esculenta) or planted as sole crop in rotation with cassava. Mucuna pruriens and Canavalia ensiformis were found to produce almost similar amount of biomass. The two legumes, however, produced higher biomass in rotation than intercropping system. The amount of biomass produced by Mucuna pruriens and Canavalia ensiformis in rotation system was 6.28 t·ha-1 and 5.31 t·ha-1, respectively. The Mucuna use represents an input of nitrogen into the soil which simulates a saving cost of 181.42 and 141.96 US$ ha-1. In the first year, cassava root yields were significantly increased (p -1) by the use of intercropping of cassava (Manihot esculenta) with Mucuna pruriens (2.41 t·ha-1) and or Canavalia ensiformis (2.25 t·ha-1). Intercropping and rotation of cassava with legumes increase cassava yield and represent a sustainable alternative to reduce the farms’ dependence on external inputs and to enhance inherent soil fertility.

Alfalfa (Medicago sativa L.) overseeding on mature switchgrass (Panicum virgatum L.) stand: biomass yield and nutritive value after the establishment year

Perennial crops can positively act on the environment providing a better inter-annual protection of soil cover from water erosion, limiting soil fertility degradation, the risk of nutrient leaching and the exploitation of water for irrigation. Switchgrass (Panicum virgatum L.), a warm-season grass native from North America, has been cultivated for decades as forage crop and only recently as bioenergy crop. Even if several studies reported a positive effect of nitrogen (N) supply on switchgrass yield and quality, potential indirect and direct environmental risks (e.g., eutrophication and greenhouse gas emission) are related to this practice. For this reason grass-legume intercropping can represent a sustainable practice able to increase biomass yield and quality, and at the same time to improve N use efficiency, soil structure and fertility. Based on this, the aim of this study was to evaluate the suitability of switchgrass to Mediterranean environment as forage crop and to improve biomass yield and its nutritional value by intercropping with alfalfa (Medicago sativa L). During spring 2013, in two switchgrass pure stands (varieties Alamo and Blackwell, respectively), alfalfa was established through direct seeding implementing a split-plot experimental design. Our first year results report a positive effect of the intercropping in increasing the total annual yield of the stand, of about 20% with respect to the pure switchgrass stand. However, the presence of alfalfa negatively affected switchgrass yield in the mixture. In both varieties, the crude protein content was higher in the mixture than in the pure switchgrass stands. Conversely, the neutral detergent fibre content in the mixture was lower than in pure switchgrass. Then, our results show that switchgrass-alfalfa intercropping leads to increase the profitability of grassland-based livestock production.

Methodology of effective monitoring of a soil cover (on the basis of the analysis of 25-years European experience)

The purpose of the article is to state the most essential methodological aspects of monitoring of a soil cover which is spent in the Europe during more than 25 years, to approach the Ukrainian model of monitoring to European and to formulate requirements to the organization of monitoring in Ukraine which will guarantee its efficiency. According to the European concept under monitoring the existential system of supervision over soil properties on constant platforms with use of the wide program of indicators with the purpose of creation of information-analytical databases, divisions into districts and allocation of problem territories, the forecast of soil development (including by means of pedotransfer modelling), a correcting of the contents and intensity of agricultural activity, planning of soil-saving actions, improvements of granting process to farmers, activization of work with mass media and in other purposes means. Advantage has regular distribution of points which meets the requirements of geostatistic analysis and geoinformatics is better and is better considers spatial features of soil characteristics which are important in mapping. Organizational principles of construction of monitoring: independence of departments influence; simple 2-unit structure (regional laboratory – the centre of information-analytical), the coordinated and approved normative estimated base; coordination with supervision over other components of an environment; financing from the state budget; regular informing on results power structures and the public. Monitoring is meaningful only when with its help a long number of the equidistant supervision received mainly in a regular network is formed. Only under these conditions probably objective estimation and the reliable forecast of negative changes in soils, and also contours of territories with problem characteristics are precisely defined. Accordingly means for their elimination are economically spent. Monitoring should be spent at the greatest possible quantity of definitions of display soil properties in modes in situ and on-line. Mainly by results of monitoring a soil cover in the majority of the European countries bases of a new agrarian policy protection of an environment and active support of soil-saving technologies to which interest increases in the European countries have been certain is. In the European countries the atmosphere of assistance to monitoring was generated and it is considered, that without high-quality information system about a soil cover to create comfortable conditions of a life and a clean environment is impossible. In Ukraine it is necessary to organize monitoring of a soil cover on the basis of the newest program, mathematical tool, and cartographical bases, agreed with the European experience. In connection with intensive use the soil cover of Ukraine quickly changes, the increasing urgency is got with processes of degradation. Therefore the control of changes and over its base formation of corresponding programs on stay of degradation and reproduction of soil fertility – very actual problem.

Tanggap Tiga Varietas Padi Sawah terhadap Kombinasi Pemupukan dengan Sistem Pembenaman Jerami

<p>ABSTRACT</p><p>Degradation of soil fertility due to inaccurate application of fertilizer become one of the factors causing the stagnant rice productivity improvement in Indonesia. Straw incorporation, organic fertilizers and biofertilizers applications potentially reduces a rates of inorganic fertilizers and improves soil fertility. The aim of this study was to evaluate growth and yield of 3 lowland rice varieties (high yielding variety, new plant type, and local variety) in response to reduce NPK rates with straw incorporation, organic fertilizer, and biofertilizer in 7th planting season. The research was conducted at rice field in Karawang, West Java, from April-August 2013. The research was arranged in split plot randomized block design with 3 replications. The main plot was fertilizer application consisted of 10 treatments (combination of organic and inorganic fertilizers), while the sub plot was rice varieties (Ciherang, IPB 3S, and Mentik Wangi). The application of inorganic fertilizer, 400 kg NPK 30-6-8 ha-1, was control treatment. Plot size was 6.5 m x 10 m, with a double row spacing (25 cm x 15 cm x 50 cm). The result showed that growth of the three varieties was not significantly different so as the yield at 50% reduced NPK rate with incorporation of straw, organic fertilizer and biofertilizer. Adding of solid and liquid organic fertilizer, and biofertilizers on treatment of straw incorporation + 50% NPK rate was unnecessary due to insignificant yield increase.</p><p>Keywords: Ciherang, fertilizer, IPB 3S, local variety, Mentik Wangi, new plant type</p>

SOIL QUALITY INDEX IN THE UPSTREAM OF BENGAWAN SOLO RIVER BASIN ACCORDING TO THE SOIL FUNCTION IN NUTRIENT CYCLING BASED ON SOYBEAN PRODUCTION IN AGROFORESTRY

Over the function of the upstream region watersheds causes the soil susceptible to degradation of soil fertility. Agroforestry systems that have been implemented should be reviewed to determine their effectiveness in improving soil fertility using a soil quality index. The varieties of soybean that cultivated in the study site were Grobogan, Kaba, and Argomulyo. The variables of this study consists of organic-C, pH, cation exchange capacity (CEC), total-N, available-P, available-K, Na, Ca, Mg, base saturation, and electrical conductivity (EC). Soil quality index calculation performed on selected outcome variables principal component analysis (PCA) which is then multiplied by the weights index on each PC. Selected variables from PCA consist of available-P, available-K, base saturation, and pH. Soil quality index values for all types of Agroforestry in the upstream of Bengawan Solo river basin ( Wonogiri ) is under secondary forest (<4.1) so that it can be concluded that the adoption of Agroforestry in the upstream of Bengawan Solo river basin has not effect on soil quality based on soil functions in the recycling of nutrients. Mean of soybean grain yield in agroforestry system are higher than the mean of national soybean production, but there are an obstacle such as light conditions.

Agroecological estimation of the mineralogical composition of the soil

It is shown that the mineralogical composition of the soil is a factor when considering the lithology of soil at a lower hierarchical level. The mineralogical composition and determines the content ratio in the soil of nutrients and toxicants, ion exchange processes, soil resistance to degradation of soil fertility. It is the matrix of the formation of soil and regulates the transformation, migration and accumulation in soil of substances, energy and information of environmental and human impact.

Germination and Early Seedling Growth of &amp;lt;i&amp;gt;Moringa oleifera&amp;lt;/i&amp;gt; Lam with Different Seeds Soaking Time and Substrates at the Yongka Western Highlands Research Garden Park (YWHRGP) Nkwen-Bamenda, North-West Cameroon

Moringa oleifera is a multipurpose tree used to remedy problems related to food insecurity and soil fertility degradation. Proper husbandry of this crop is contingent on the use of seedlings of good quality. This study aimed at assessing the germination and early seedling growth with different soaking durations and substrates composition. The seeds were obtained from the Far North region of Cameroon. A randomized complete block design with three replications was used. Two factors were tested; soaking duration with 4 treatment levels of 0 day, 4 days, 8 days and 12 days and substrates with 8 treatment levels: 100% soil, 75% soil + 25% poultry manure (PM), 50% soil + 50% PM, 25% soil + 75% PM, 100% sand, 75% sand + 25% PM, 50% sand + 50% PM and 25% sand + 75% PM. Germinated seeds and growth parameters were collected after every 5 days. The results showed that soaking duration and substrate composition influence germination and initial development of M. oleifera (p ≤ 0.05). At 25 days after soaking (DAS), soaking durations of 0 day (68.7%) and 8 days (53.1%) showed the highest germination percentages while seeds soaked for 12 days occupied the least position with 37.5%. At the same time, 75% soil + 25% PM (68.7%), 100% sand (64.5%) and 100% soil (60.5%) with the unsoaked seeds showed the highest germination percentages. The least germination percentages were represented by 50% sand + 50% PM and 25% sand + 75% PM with 35.5% and 27%, respectively. Unsoaked seeds with the substrates of 50% soil + 50% PM are the best practice for M. oleifera seedling production in the nursery.

Degradation of soil fertility can cancel pollination benefits in sunflower.

Pollination and soil fertility are important ecosystem services to agriculture but their relative roles and potential interactions are poorly understood. We explored the combined effects of pollination and soil fertility in sunflower using soils from a trial characterized by different long-term input management in order to recreate plausible levels of soil fertility. Pollinator exclusion was used as a proxy for a highly eroded pollination service. Pollination benefits to yield depended on soil fertility, i.e., insect pollination enhanced seed set and yield only under higher soil fertility indicating that limited nutrient availability may constrain pollination benefits. Our study provides evidence for interactions between above- and belowground ecosystem services, highlighting the crucial role of soil fertility in supporting agricultural production not only directly, but also indirectly through pollination. Management strategies aimed at enhancing pollination services might fail in increasing yield in landscapes characterized by high soil service degradation. Comprehensive knowledge about service interactions is therefore essential for the correct management of ecosystem services in agricultural landscapes.

Indigenous Phosphate Solubilizing Bacteria from Peat Soil for an Eco-friendly Biofertilizer in Oil Palm Plantation

&lt;p&gt;Degradation in soil fertility is an enormous problem in agricultural intensification system. Availability in phosphate is one of among encountered problems. Peat soils have large areas and great potential for agriculture and plantations, but have many obstacles in their management. One of the issues is the low soil fertility and low availability of nutrients, especially phosphate which exists in many organic forms that are not available to plants. Phosphorous is an essential element after nitrogen, which plays an important role in plant growth and metabolism and the process of soil microbiology. Introduction of phosphate- solubilizing bacteria (PSB) as biofertilizer, is a renewable energy based which can increase the availability of phosphate to plants can overcome this problem and at the same time reducing the use of inorganic P fertilizer. Indigenous PSB, isolated from palm oil plantation could be used as a better and friendly bio-agent to improve soil fertility, specifically for phosphate availability. Eight PSB have been isolated from peat soil in oil palm platation. Morphological, biochemical characterization and molecular identifications showed that the 8 isolates belonged to Flavobacterium and Enterobacter genera, more precisely the species of Burkholderia sp and Novosphingobium nitrogenifigens. Characterization of isolates of the highest PSB activity consisted of the ability to dissolve phosphate in Pikovskaya solid medium, temperature resistance optimization and the ability to produce phosphatase enzyme. Results showed that isolate with the highest potentiality of dissolving phosphate formed 3.5 cm of clear zone diameter and the phosphatase activity at 9 days of incubation 5.992 units (μmol / ml / min). The peak of enzyme’s activity was reached at 6 days , which corresponded to 54.782 ppm of phosphorus solubilised. The lowest pH (3.2) was reached at 1st day of incubation. These isolates showed the ability to grow optimally at temperature range of 25 to 300C. Indigenous PSB could be used as biofertilizer agents which are eco friendly.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Keywords&lt;/strong&gt;: indigenous; biofertilizer; renewable energy, phosphate solubilizing bacteria;phosphatase; oil palm&lt;/p&gt;

6-2-3 Degradation of soil fertility and fertilization system in the mid-hill region in Nepal

6-2-3 Degradation of soil fertility and fertilization system in the mid-hill region in Nepal

Factors Affecting Adoption of Agroforestry and Evergreen Agriculture in Southern Africa

This paper examines the factors that affect adoption of agroforestry and integrated soil fertility management (ISFM) practices in Southern Africa. Agroforestry practices, especially evergreen agriculture and conservation agriculture with trees have emerged as sustainable measures of addressing land degradation and loss of soil fertility. Although agroforestry is known to be beneficial to farmers and the environment, its adoption rate falls far behind the projected goals. The present study reviewed several publications on adoption of agroforestry in Southern Africa and complemented the review with household and key informant interviews to obtain evidence from farmers and promoters of the technologies on the factors affecting adoption. The study revealed that the major factors affecting adoption of agroforestry fall into two main categories of socioeconomic and biophysical factors. The factors are high initial costs of agroforestry practices (75%), low extension knowledge (69%); unavailability of agroforestry germplasm (69%) for economic, social and biophysical categories respectively. Up to 84% of the key informants indicated that awareness of the connection between agroforestry and land quality improvement could lead to wide scale adoption of the technology. We conclude that Government policies will strongly influence adoption of agroforestry technologies. There is need to institutionalise sustainable agricultural land management practices through policy formulation, budgetary allocation for extension officers and farmer training and starter up inputs. Promotion of agroforestry should be coupled with investment in awareness creation, farmer-centered approaches in selection of technology and provision of inputs in the initial stages. Strong collaboration among policy makers, researchers and extension providers will be required to harmonise messages to be delivered to farming communities.

English

This paper reports on studies of soil samples from the region of Xiaoliang water conservation station, in China, and its naturally restored forest. 32 indices based on the physical, chemical, microbiological and enzyme properties of the soil are studied, from 9 different vegetation patterns at 45 observation points. Grey correlation analysis and integrated evaluation is used for the analysis of soil fertility. From experimental measurements, it is shown that the integrated evaluation of the sample soil fertility by grey correlation analysis provides excellent agreement with the actual soil characteristics. Eucalyptus may be considered as a primary forest choice to recover bare land, however, it is not suitable for long-term planting and cropping since it will eventually result in degradation of soil fertility, and is therefore not favourable for long-term ecological restoration. Nevertheless, if chosen, additional actions can be taken to benefit soil fertility, such as regular changes of breed variety, crop rotation, mixing with broad-leaf forest, protecting undergrowth vegetation and reducing forest litter coverage. Key words: Grey correlation, integrated evaluation, regional scale, soil fertility, water conservation station.

Climate Change and Food Security at Salinity Prone Area in Southwest Coastal Region of Bangladesh

The availability, accessibility, utility and stability of food production and consumption interrupted due to the climatic transformation and intensity of salinity in the southwest salinity prone area of Bangladesh. 96.7% of the respondents can perceive climate change explicitly, among the 120 respondents of whom the mean age of the respondents was 50.6 years. 40.8% of the respondents responded that crops became more limited from 20 to 25 years ago. 43.3% of the respondents argued that salinity was responsible for the degradation of soil fertility. The problems of drinking water prevails that 29.79% of the respondents spent 61 taka to 80 taka monthly for water. 96.22% of the respondents availed microcredit facilities from NGO and 22.0% of the respondents used microcredit for purchasing food products. 64.2% of the respondents don’t consume nutritional foods and the day to day consumption highly depends on purchasing which was domestically produced few years ago.

Kinetics of potassium release in sweet potato cropped soils: a case study in the highlands of Papua New Guinea

Abstract. The present study attempts to employ potassium (K) release parameters to identify soil-quality degradation due to changed land use patterns in sweet potato (Ipomoea batatas (L.) Lam) farms of the highlands of Papua New Guinea. Rapid population increase in the region increased pressure on the land to intensify subsistence production mainly by reducing fallow periods. Such continuous cropping practice coupled with lack of K fertilization practices could lead to a rapid loss of soil fertility and soil-resource degradation. The study aims to evaluate the effects of crop intensification on the K-release pattern and identify soil groups vulnerable to K depletion. Soils with widely differing exchangeable and non-exchangeable K contents were sequentially extracted for periods between 1 and 569 h in 0.01 M CaCl2, and K-release data were fitted to four mathematical models: first order, power, parabolic diffusion and Elovich equations. Results showed two distinct parts in the K-release curves, and 58–80% of total K was released to solution phase within 76 h (first five extractions) with 20–42% K released in the later parts (after 76 h). Soils from older farms that were subjected to intensive and prolonged land use showed significantly (P &lt; 0.05) lower cumulative K-release potential than the farms recently brought to cultivation (new farms). Among the four equations, first-order and power equations best described the K-release pattern; the constant b, an index of K-release rates, ranged from 0.005 to 0.008 mg kg−1 h−1 in the first-order model and was between 0.14 and 0.83 mg kg−1 h−1 in the power model for the soils. In the non-volcanic soils, model constant b values were significantly (P &lt; 0.05) higher than the volcanic soils, thus indicating the vulnerability of volcanic soils to K deficiency. The volcanic soils cropped for several crop cycles need immediate management interventions either through improved fallow management or through mineral fertilizers plus animal manures to sustain productivity.

Contrasting impacts of grass species on nitrogen cycling in a grazed Sudanian savanna

We investigated the impact of perennial and annuals grass species on nitrogen cycling in a Sudanian savanna of Burkina Faso. We also analysed how the local context in terms of grazing and soil properties modifies these impacts. We selected four plots differing both by the intensity of grazing by cattle and soil depth, and used soil and grass biomass 15N as integrative indicators of N cycle. If perennials are able to foster a more efficient nitrogen cycling there should be lower 15N abundances in their biomass and soil. If soil depth and cattle pressure significantly modify nitrogen fluxes, soil depth and cattle pressure should influence 15N signatures. Our results suggest that perennial grasses are more conservative for nitrogen (inhibition of nitrification, less leaching via a perennial root system, slower cycling). The increase in leaf δ15N with N concentration is steeper in Loudetia togoensis than in the three other grasses. No significant difference was found between the 15N signatures of the four plots. Our results on 15N signatures and the fact that perennial grasses are much more abundant in the plots that are less grazed and have deeper soils, confirm that the switch from perennial to annual grasses is linked to a degradation in soil fertility and pasture quality. This suggests that 15N signatures can be used as indicators of fertility.

南亚热带格木、马尾松幼龄人工纯林及其混交林生态系统碳氮储量

PDF HTML阅读 XML下载 导出引用 引用提醒 南亚热带格木、马尾松幼龄人工纯林及其混交林生态系统碳氮储量 DOI: 10.5846/stxb201401030018 作者: 作者单位: 中国林业科学研究院,中国林业科学研究院,中国林业科学研究院,中国林业科学研究院,中国林业科学研究院热带林业实验中心 作者简介: 通讯作者: 中图分类号: 基金项目: 中国科学院碳专项(XDA05060100);林业公益性行业科研专项(201104006) Carbon and nitrogen storage in monoculture and mixed young plantation stands of Erythrophleum fordii and Pinus massoniana in subtropical China Author: Affiliation: Chinese Academy of Forestry,Chinese Academy of Forestry,Chinese Academy of Forestry,Chinese Academy of Forestry,Experimental Center of Tropical Forestry,Chinese Academy of Forestry Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:研究比较了南亚热带6年生格木(Erythrophleum fordii)、马尾松(Pinus massoniana)幼龄人工纯林及马尾松与格木混交林生态系统碳氮储量及其分配特征。结果表明,生态系统总碳储量依次为马尾松-格木混交林(137.75 t/hm2) >格木纯林(134.07 t/hm2) >马尾松纯林(131.10 t/hm2),总氮储量则为格木纯林(10.19 t/hm2) >马尾松-格木混交林(8.68 t/hm2) >马尾松纯林(7.01 t/hm2)。3种人工林生态系统碳氮库空间分布基本一致,绝大部分储存于0-100 cm土壤层,平均占生态系统总储量的81.49%和96.91%,其次为乔木层(分别占17.52%和2.69%),林下植被和凋落物层所占比例最小。林地土壤碳主要集中于表土层,其中0-30 cm土层平均碳储量为52.52 t/hm2,占土壤总碳储量(0-100 cm)的47.99%,土壤氮的分布则无明显规律。相比于纯林,与固氮树种混交的营林方式表现出更大的碳储存能力。3种幼龄人工林生态系统较低的地上与地下部分碳氮分配比,表明其仍具有较强的碳氮固持潜力。 Abstract:Carbon sequestration in forest ecosystems is recognized as a key mechanism for mitigating the accumulation of atmospheric carbon dioxide. However, both forest carbon pools and sequestration vary according to tree species, age of the stand, soil types, climate, environmental disturbances, and management practices. Tree species composition and management practices are important tools for increasing carbon storage in forest ecosystems. Plantation is becoming a key component of the world's forest resources and is playing an important role in sustainable forest management. Well-designed, multi-purpose plantations can reduce the pressure on natural forests and complement some ecological resources provided by natural forests in addition to mitigating climate change through direct carbon sequestration. Afforestation and reforestation are important measures for managing commercial forests in subtropical China. However, the large-scale development of monoculture plantations of coniferous species (e.g., Pinus massoniana and Cunninghamia lanceolata) and exotic species (Eucalyptus spp.) has caused a number of problems, such as the loss of biodiversity, degradation of soil fertility, reduction of ecosystem stability, and loss of ecological resources. Thus, some broad-leaved tree species with different functions (e.g., indigenous valuable broad-leaved species and nitrogen-fixing species) have been developed for restructuring the plantations. In this study, three young plantation stands (monoculture of Erythrophleum fordii, monoculture of P. massoniana and a mixed stand of the two species) were selected to study carbon and nitrogen storage in these ecosystems and their spatial distribution. The results showed that the total carbon storage of the mixed plantation stand was 137.75 t/hm2, higher than that of monoculture stands of E. fordii (134.07 t/hm2) and P. massoniana (131.10 t/hm2). Nitrogen storage was highest in E. fordii (10.19 t/hm2), followed by the mixed plantation (8.68 t/hm2), and then P. massoniana stands (7.01 t/hm2). The spatial distribution of carbon and nitrogen was identical in the three plantation stands, with the majority found in the 0-100 cm soil (occupying an average 81.49% and 96.91% of the total storage, respectively), followed by the above-ground biomass represented by the trees (17.52% and 2.69%, respectively), and the understory vegetation and litterfall. Soil organic carbon was mainly distributed in the top-soil, while soil nitrogen was irregularly distributed. Average organic carbon storage in 0-30 cm soil was 52.52 t/hm2 (47.99% of the total 0-100 cm soil storage). The mixed plantation stands showed a greater capacity for carbon storage in comparison to the other two monoculture stands. The above-/underground ratio of carbon and nitrogen suggested that these three young plantation stands had a high potential for carbon and nitrogen sequestration. The results are significant in that they provide scientific references for tree species selection and plantation management to enhance productivity and carbon sequestration in subtropical China. 参考文献 相似文献 引证文献

Advance research on Striga control: A review

The parasitic weed–(Striga spp.), is a major biotic constraint and a serious threat to subsistence cereal crop (sorghum, maize, pearl millet, finger millet and upland rice) production in sub-Saharan Africa. Severity of the parasitic weed in this area is aggravated by the inherent low soil fertility, recurrent drought and overall natural resource degradation. Striga hermonthica (Del.) Benth. and S. asiatica (L.) Kuntze are the major biotic constrains to crop production, especially in the non-fertile semi-arid region of Africa, whereas S. aspera (Willd.) Benth. and S. forbesii Benth. are of lower economic importance. Striga produces numerous minute seeds, which can remain dormant in the soil for as long as up to 20 years. Yield losses due to Striga damage range between 20-80% in Africa but total crop failure is possible in the worst situations. A review of these findings has been discussed for the benefit of poor-resource farmers. Based from these findings, different control measures has been recommended in tackling the negative effects of this weed. Striga can be managed using one or more methods: use of cultural and mechanical control practices, nitrogen fertilizers, push pull technology, biological control practices, resistant host crops, use of herbicides and integrated Striga control methods. However, an integrated Striga management strategies suitable approach, a combined use of two or more control measures, is required to achieve success against this pernicious weed. Key words: Striga spp., host crops, crop losses, control methods.

Grain Productivity, Fertilizer Response and Nutrient Balance of Farming Systems in Tigray, Ethiopia: A Multi‐Perspective View in Relation to Soil Fertility Degradation

AbstractApplication of nutrients is an important way to increase crop productivity. In our study area, Tigray, development agents recommend fertilizer application to boost productivity and counteract nutrient depletion. We analysed soil fertility from different perspectives, using responses and nutrient balances on the basis of on‐farm experimentation. Three perspectives, embedded in the People–Planet–Profit framework and with different temporal and spatial scales and ownership, were considered. Taking a farmer perspective, we found no significant differences in response between recommended and current farmer practices. Taking an agronomist perspective, phosphorus seemed to limit productivity. It however also became obvious that closing nutrient balances at field scale to achieve sustainability is difficult. Only by using considerable amounts of manure and at the cost of productivity this can be achieved. From a long‐term environmentalist perspective, the traditional agricultural system seems sustainable in combining mixed farming and relatively low yields. We conclude that depending on the perspective taken, different interventions will be appropriate. All perspectives however indicate that gradually strengthening the existing mixed farming system by using fertilizers, organic manure and legume fallows supports crop productivity while maintaining other aspects of sustainability such as food security and profitability. In line with this, our analysis of different perspectives suggests that in our study area, farmers will only consider transitions with low risk and this specifically should be addressed in proposing pathways of transition. In processes where stakeholders with different perspectives cooperate, it is important to be aware and make use of the possibilities of comparable multi‐perspective analyses. Copyright © 2014 John Wiley &amp; Sons, Ltd.

Options to improve family income, labor input and soil organic matter balances by soil management and maize–livestock interactions. Exploration of farm-specific options for a region in Southwest Mexico

AbstractFarming systems in the Costa Chica region in Mexico face limitations linked to low yields and soil fertility degradation. Several alternative maize-based cropping systems have been proposed to improve current limitations. These field-level options need to be evaluated at farm level in order to assess their feasibility, taking into account input requirements, contributions to self-sufficiency in food and long-term soil fertility, and the availability of labor. In this study, we defined four scenarios to explore consequences of changes in current farming systems for eight typical farms in the region; the first two scenarios comprised redressing current imbalances in crop nutrition and organic matter (OM) supply, respectively, and the last two scenarios explored high fertilizer input and animal husbandry. Farms responded in different ways to the various options depending on available land, current soil quality, current cropping systems and presence of livestock. Improvements in crop nutrition based on mineral fertilizers increased family income but only had substantial effects on soil OM (SOM) balances when fertilizer rates were double the amount currently subsidized. Addition of organic fertilizers resulted in positive effects on SOM balance, but with often strong trade-offs with family income due to costs of acquisition, transport and application. Animals played an important role in increasing SOM balances, but had relatively little effect on improving family income. The results demonstrated that improvements in family income and SOM balance at farm scale were feasible but that without more fundamental system changes trade-offs between short-term yield increases and longer-term soil fertility increases should be expected. The results highlight the need for policies that take into account farm-specific differences in crop and livestock intensification opportunities.

Effect of 26 Years of Intensively ManagedCarya cathayensisStands on Soil Organic Carbon and Fertility

Chinese hickory (Carya cathayensis), a popular nut food tree species, is mainly distributed in southeastern China. A field study was carried out to investigate the effect of long-term intensive management on fertility of soils under a C. cathayensis forest. Results showed that after 26 years' intensive management, the soil organic carbon (SOC) content of the A and B horizons reduced by 19% and 14%, respectively. The reduced components of SOC are mainly the alkyl C and O-alkyl C, whereas the aromatic C and carbonyl C remain unchanged. The reduction of active organic matter could result in degradation of soil fertility. The pH value of soil in the A horizon had dropped by 0.7 units on average. The concentrations of the major nutrients also showed a decreasing trend. On average the concentrations of total nitrogen (N), phosphorus (P), and potassium (K) of tested soils dropped by 21.8%, 7.6%, and 13.6%, respectively, in the A horizon. To sustain the soil fertility and C. cathayensis production, it is recommended that more organic fertilizers (manures) should be used together with chemical fertilizers. Lime should also be applied to reduce soil acidity.