Maintenance Of Soil Fertility Research Articles

Effects of quebracho tannin extract (Schinopsis balansae Engl.) and activated charcoal on nitrogen balance, rumen microbial protein synthesis and faecal composition of growing Boer goats

ABSTRACTUnder irrigated arid conditions, organic fertiliser rich in slowly decomposable nitrogen (N) and carbon (C) is needed for soil fertility maintenance. Feeding ruminants with condensed tannins will lower ruminal protein degradation, reduce urinary N excretion and might increase the faecal fraction of slowly decomposable N. Supplementation with activated charcoal (AC) might enrich manure with slowly degrading C. Therefore, we investigated the effects of feeding quebracho tannin extract (QTE) and AC on the N balance of goats, the efficiency of microbial protein synthesis in the rumen (EMPS) and the composition of faeces. The feeding trial comprised three periods; in each period, 12 male Boer goats (28 ± 3.9 kg live weight) were assigned to six treatments: a Control diet (per kg diet 500 g grass hay and 500 g concentrate) and to further five treatments the Control diet was supplemented with QTE (20 g and 40 g/kg; diets QTE2 and QTE4, respectively), with AC (15 g and 30 g/kg, diets AC1.5 and AC3.0, respectively) and a mixture of QTE (20 g/kg) plus AC (15 g/kg) (diet QTEAC). In addition to the N balance, EMPS was calculated from daily excretions of purine derivatives, and the composition of faecal N was determined. There was no effect of QTE and AC supplementation on the intake of organic matter (OM), N and fibre, but apparent total tract digestibility of OM was reduced (p = 0.035). Feeding QTE induced a shift in N excretion from urine to faeces (p ≤ 0.001) without altering N retention. Total N excretion tended to decrease with QTE treatments (p = 0.053), but EMPS was not different between treatments. Faecal C excretion was higher in QTE and AC treatments (p = 0.001) compared with the Control, while the composition of faecal N differed only in concentration of undigested dietary N (p = 0.001). The results demonstrate that QTE can be included into diets of goats up to 40 g/kg, without affecting N utilisation, but simultaneously increasing the excretion of slowly decomposable N and C fractions. Feeding AC up to 30 g/kg of the diet increases slowly degradable faecal C concentration, without negative effects on N metabolism of goats.

Sustainable viticulture: The carbon-sink function of the vineyard agro-ecosystem

In addition to food production, tree crop-based agrosystems can provide other ecosystem services (ES) such as soil fertility maintenance, soil and water retention and landscape preservation. Tree crops can also act as carbon (C) storage facilities and climate change mitigating systems. We focus on the nature of viticulture as a provider of ES, in particular C storage. This study has been carried out focusing on two different wine-grape growing areas in central Italy (Latium region; natural and peri-urban hilly areas) where the vines (Vitis vinifera sativa L., cv Merlot) were cultivated according to two different management techniques (conventional vs organic farming). Grapevine C storage levels were analyzed in the two main vine C pools during the 2011 and 2012 growing seasons, i.e., above-ground and below-ground biomass, in accordance with the Net Ecosystem Production (NEP) methodology. In order to quantify C sequestration at the vineyard level, we determined soil C sequestration and soil functionality through the measurement of Total Organic Carbon (TOC), microbial biomass and soil and grapevine root respiration. To conclude, the net C balance was assessed at both the grapevine and the vineyard scale.Although the highest dry matter partitioning in the grapevines was measured in the above-ground organs, the root systems contributed to between 9 and 26% of the total vine C fixation. The soil’s C fixation was maximized in the organically managed vineyards (73.35tCha−1). The CO2 sequestration of one hectare of vineyard ranged between 5.72 (±0.07) and 7.23(±1.11)tCha−1year−1. Soil respiration represented the main (99%) CO2 emission source in the vineyard agro-ecosystems.The Principal Component Analysis (PCA) indicated that the soil physical characteristics, the grapevine’s biological properties, and the vineyard’s management techniques, like those handling the inter-row space that highly differ in the organic and conventional farming, turned out to be the main factors influencing the soil’s C storage and consequently the vineyard’s C balance.Together, these findings prove that vineyards can act as C sinks, if properly managed. Furthermore, vineyards could represent a crucial cropping system able to provide pivotal ecological services such as carbon dioxide sequestration. Viticulture can also contribute to the preservation and regulation of natural resources –, such as soil and agricultural landscapes, according to the new European Commune Agricultural Policy (CAP).

Support vector machines and generalized linear models for quantifying soil dehydrogenase activity in agro-forestry system of mid altitude central Himalaya

In natural ecosystems, the linkages between inputs of carbon from plants, soil moisture (SM) and microbial activity are central to our understanding of nutrient cycling. Predictions of microbial activities in soil are important as they indicate the potential of the soil to support biochemical processes that are essential for the maintenance of soil fertility as well as productivity. The dehydrogenase activity (DHA) in soil provides information on microbial activities of the soil. However, estimation of DHA activity over complex terrain such as soils of the central Himalaya is not always possible due to very harsh environment and climatic conditions. In this study, the attempts were made to estimate the DHA in the soil of mid altitude central Himalaya using computational intelligence techniques. The linear and non-linear correlation results indicate that the fluctuations in SM and organic carbon (OC) in the root zone affect DHA and can be used as predictors for DHA. Therefore, the performances of support vector machines (SVMs) and generalized linear models (GLMs) were attempted for the prediction of DHA over mid altitude central Himalaya using information of SM and OC. The results showed that the SVM was giving a much better performance than GLM using SM and OC and could be promising and cost effective approach for soil DHA prediction over complex ecosystem. Our results are also of considerable scientific and practical value to the wider scientific community, given the number of practical applications and research studies in which SM and OC datasets are used.

Effect of NPK 16-16-16, poultry-mushroom waste compost and their combinations on growth and yield of okra

A pot experiment was conducted to study the effects of poultry-mushroom waste compost (PMWC), NPK 16-16-16 (NPK) and their combined applications on vegetative growth and yield of okra [Abelmoschus esculentus (L.) Moench] during June-November 2014. The experiment included nine treatments: Unfertilized control (T1), NPK 2.5 g/kg (T2), NPK 5 g/kg (T3), NPK 10 g/kg (T4), NPK 2.5 g/kg+PMWC 120 g/kg (T5), NPK 5 g/kg+PMWC 120 g/kg (T6), PMWC 60 g/kg (T7), PMWC 120 g/kg (T8) and PMWC 240 g/kg (T9). Results showed that all fertilizations increased growth and yield of okra compared with no fertilization. 10 g/kg NPK (T4) greatly inhibited the growth of plant height before 30 days after sowing (DAS) and leaf growth before 15 DAS, with maximum numbers (19.17) of flowers and minimum fruit-setting rate (35.26%). 5 g/kg NPK combined with 120 g/kg PMWC (T6) advanced maximum growth rate of plant height and most greatly enhanced early flowering. T9 with 240 g/kg PMWC obtained maximum numbers (9.83) of fruits. Individual applications of NPK (T2, T3 and T4) significantly promoted more fallen leaves and higher defoliation ratio at 90 DAS over other treatments and decreased the fruit-setting rate as increasing NPK levels. Individual applications of PMWC increased plant height, leaf number and fruit number with increasing PMWC levels. As mentioned above, application of 240 g/kg PMWC is recommended in south-eastern China for its highest yield, low cost of production and maintenance of soil fertility.

Nutrient Usage in Punjab Agriculture-Status and Constraints

Many natural resources, which were once regarded as free goods, have now become scarce resources. Economic development affects the environment more often in a negative way, same is true for land use in Punjab agriculture. The profitable combination of rice-wheat crops has led to higher doses of inputs like chemical fertilizers and pesticides. But, the trend undertaken to sustain productivity in an imbalanced way has affected the soil health adversely. Excessive use has created deficiencies of nutrients in the soil leading to higher fertilization, increased costs and squeezing profit margins. Consumption of chemical fertilizers was found to be almost double of Indian consumption in 2012–13. Nutrient cost in Punjab was found to be about 18 per cent of the total operational cost in wheat crop, followed by 12.5 per cent in paddy and nearly eight per cent in case of cotton crop respectively. Sampled farmers in sub-mountainous zone (zone I) were found to be using fertilizer sprays according to recommendation, followed by zone III and lastly by zone II. Zone II is the central plain zone or wheat paddy zone, where farmers were not using fertilizers as per the package of practices. If we see category-wise, small farmers were using fertilizers more optimally than medium and large farmers in the state. The expenditure on fertilizer use was higher than that calculated at recommended level of fertilize use. The prominent reason to use higher levels of fertilizer than recommended was cited as to enhance the yields of crops, followed by maintenance of soil fertility and to cope with deficit rains/water availability. Only 2 per cent of the farmers showed ignorance about proper knowledge regarding fertilizer doses but they highlighted the constraints regarding the issue and the associated environmental problems to be solved.

Effect of Mineral and Organic Nutrient Management on Sweet Corn Production System in Acid Lateritic Soil of India

Introduction: Nutrient management plays a key role in improving crop yield with maintenance of soil fertility for sustainable production in intensive cropping. Aim: A field experiment was conducted to study the effect of organic and mineral sources of fertilizer on yield and quality of sweet corn grown in acid laterite soil of India during the years 2009 and 2010. Materials and Methods: The organic inputs were vermicompost (VC), vermiwash (VW), biofertilizer (BF), and crop residue (CR) and the inorganic input was mineral fertilizer. Results: Optimal application of N, P, and K (100% recommended dose) either through organic source or mineral source was significantly superior to their suboptimal dose in increasing the yield of sweet corn, wherein mineral fertilizer recorded maximum production. Between organic and mineral sources of fertilizer application, ascorbic acid and total phenolics content of sweet corm were higher in organic nutrient management. The ascorbic acid was higher by 133% in VC100 and 37% in VC50 + CF50 compared to mineral (CF100) treatment. But crude protein content was low by 13.5% in VC100 and 2.9% in VC50 + CF50, respectively, as compared to CF100 treatment. Organic carbon content and pH of the acid lateritic soil were improved in organic nutrient management as compared to mineral fertilizer. Conclusion: Organic fertilizer application, therefore, exhibited potential in improving sweet corn yield and quality and soil health in acid lateritic soil of the subtropical climate.

Validation of Soil Test and Yield Target Based Balanced Fertilizer Prescription Model for Rainfed Maize on Inceptisol

Soil Test Crop Response based fertilizer prescription equations for desired yield target of rainfed maize were developed under Integrated Plant Nutrition System (STCR-IPNS) on Irugur soil series (Typic Ustropept) of Tamil Nadu. On farm testing of fertilizer prescription equations are essential to demonstrate the effectiveness of technology delivery to the stake holders in need. The present study was undertaken to evaluate the targeted yield model through field experiments at six locations in Dindigul district, Western Zone of Tamil Nadu. The treatments included control, blanket recommendation, soil test crop response (STCR) based fertilizer dose for the yield targets of 4.0 to 6.0 t ha-1 , STCR-IPNS based fertilizer dose for the yield targets of 4.0 to 6.0 t ha-1 and farmer’s practice. In all the six locations, the per cent achievement of the targeted yield was within  10 per cent variation proving the validity of the equations for prescribing integrated fertilizer doses for rainfed maize. The highest mean grain yield was recorded in STCR-IPNS – 6.0 t ha-1 (5013 kg ha-1 ) recording an increase of 52.2 per cent over blanket recommendation. The highest per cent achievement, response ratio and B:C ratio of 97.2,17.47 and 2.28, respectively were recorded in the yield target of 5.0 t ha-1 under STCR-IPNS. The post-harvest soil available NPK indicated the build up and maintenance of soil fertility due to soil test based fertilizer recommendation under IPNS. The fertilizer prescription equations developed for rainfed maize under IPNS can be recommended for red non calcareous soils of Tamil Nadu for achieving the yield target of 5.0 t ha-1 with sustained soil fertility and it can be extrapolated to other agro-climatic zones of Tamil Nadu on similar and allied soil types.

English

It is essential to find ways and mean to increase the yield and lessen the cost of production so that there is enough fruit production to meet the requirement of the consumers. The yearly growth of plants, excessive growth of weeds and production of fruits deplete the soil of its nutrient reserves resulting in reduction of native-soil fertility. Mulching of organic and inorganic materials create favourable conditions for getting maximum production of quality fruits on sustainable basis within the limits of soil, water and fertility management. There is a need to conserve soil moisture and reduce weed population for proper maintenance of soil moisture and fertility. Mulching is thus, one of the most important cultural practice which affects growth, yield and quality in fruit crops. Tree growth is greatly influenced by the use of different organic and inorganic mulching materials. They conserve soil moisture in the root zone of fruit trees. The presence of adequate moisture in the soil is vital for growth and physiological processes. Besides conserving moisture, mulching also prevents sudden and extreme temperature changes, reduces erosion by wind or water, checks surface run-off and suppresses the weed growth. The application of organic and inorganic mulches in fruit orchards create an additive effect by restricting the nutrient removal through weeds and ultimately creating favourable conditions for availability of nutrients for getting higher productivity of good quality fruits on sustainable basis.   Key words: Mulching, growth, fruit quality, yield, moisture conservation, weed control.

Effects of Nitrogen Addition on Leaf Decomposition of Single-Species and Litter Mixture in Pinus tabulaeformis Forests

The litter decomposition process is closely correlated with nutrient cycling and the maintenance of soil fertility in the forest ecosystem. In particular, the intense environmental concern about atmospheric nitrogen (N) deposition requires a better understanding of its influence on the litter decomposition process. This study examines the responses of single-species litter and litter mixture decomposition processes to N addition in Chinese pine (Pinus tabulaeformis Carr.) ecosystems. Chinese pine litter, Mongolian oak (Quercus mongolica Fisch. ex Ledeb.) litter, and a pine–oak mixture were selected from a plantation and a natural forest of Chinese pine. Four N addition treatments, i.e., control (N0: 0 kg N ha−1·year−1), low-N (N1: 5 kg N ha−1·year−1), medium-N (N2: 10 kg N ha−1·year−1), and high-N (N3: 15 kg N ha−1·year−1), were applied starting May 2010. In the plantation, N addition significantly stimulated the decomposition of the Chinese pine litter. In the natural forest, N addition had variable effects on the decomposition of single-species litter and the litter mixture. A stimulatory effect of the high-N treatment on the Chinese pine litter decomposition could be attributed to a decrease in the substrate C:N ratio. However, an opposite effect was found for the Mongolian oak litter decomposition. The stimulating effect of N addition on the Chinese pine litter may offset the suppressive effect on the Mongolian oak litter, resulting in a neutral effect on the litter mixture. These results suggest that the different responses in decomposition of single-species litter and the litter mixture to N addition are mainly attributed to litter chemical composition. Further investigations are required to characterize the effect of long-term high-level N addition on the litter decomposition as N deposition is likely to increase rapidly in the region where this study was conducted.

Macronutrient status and yield stability of arecanut (Kahikuchi) under integrated nutrient management practice in Assam

<div><table cellspacing="0" cellpadding="0" align="center"><tbody><tr><td align="left" valign="top"><p>A long term field experiment was carried out in clay-loam soil at ICAR-CPCRI, Kahikuchi campus, Guwahati, Assam during 2000-2012 with arecanut variety Kahikuchi with seven nutrient combinations. The treatments included control (T1), 100 per cent vermicompost (T2), 200 per cent vermicompost (T3), 100 per cent chemical fertilizer (T4), 50 per cent vermicompost + 50 per cent chemical fertilizer (T5), 1/3<sup>rd</sup> vermicompost + 2/3<sup>rd</sup> chemical fertilizer (T6) and 2/3<sup>rd</sup> vermicompost + 1/3<sup>rd</sup> chemical fertilizer (T7). The treatment T7 produced highest fresh ripened arecanut yield of 16.7 kg <em>i.e., </em>about 3.6 kg dry chali per palm. Positive correlations were obtained between yield of arecanut and soil available N, P, K content. Significant and positive correlation was found between leaf N, P, K and available N, P, K content in surface and sub-surface soil. Available N, P and K content increased over the year under nutrient applied plot that reflected in yield of arecanut. The average yield in various treatments followed in the order of T7 > T5 = T6 > T2 = T3 > T4 > T1. The application of targeted, sufficient and balanced quantities of organic and inorganic fertilizer will be the need of the hour to make nutrients available for higher yield, soil fertility maintenance and agricultural sustainability without polluting environment.</p></td></tr></tbody></table></div>

Diversity of Soil Invertebrate Communities near the Gohagoda Dumping Site and Udawattakele Forest Reserve in Kandy, Sri Lanka

Soil faunal activity is essential for the functioning of all terrestrial ecosystems. Soil fauna are important in physical and chemical transformation of litter, maintenance of soil fertility and sustained productivity. By-products of human activities affect the proper functioning of the soil fauna with a concomitant decrease in long term soil productivity. The fauna could be used as early indicators of changes brought about in soil properties by pollutants. In Sri Lanka studies of this nature are lacking and even baseline data against which changes could be measured are not yet available. A field experiment was set up in Kandy in two forest areas near the Gohagoda dumping site and the Udawattakele forest reserve area to investigate the soil and leaf litter invertebrates. The soil invertebrate fauna was extracted in both sampling sites by using NaCl floatation method and Baermann funnel. The leaf litter invertebrates were extracted using the Tulgren funnel. Collembola, Acarina and Nematoda were the dominant phyla in both forests accounting for more than 80% of the total individuals. The Udawattakele forest area had the highest taxon and individual numbers of invertebrates. It shows that according to the Tulgren funnel method, Udawattekele area has high species diversity by both Shannon and Simpson indices which is significantly higher (<0.001). The results of Bearmann funnel method showed that it has higher diversity values for Udawattekele than Gohagoda. Overall Udawattekele has a high diversity and evenness than that of Gohagoda area. This comprehensive analysis of invertebrate diversity shows that they may be used as possible indicators of soil quality. They should also be considered as a resource that needs to be properly managed to enhance ecosystem services. Keywords: Soil invertebrates, Diversity, Gohagoda, Udawattakele

Sustainability of Wood Productivity of Pinus TaedaBased on Nutrient Export and Stocks in the Biomass and in the Soil

ABSTRACT The impact of intensive management practices on the sustainability of forest production depends on maintenance of soil fertility. The contribution of forest residues and nutrient cycling in this process is critical. A 16-year-old stand of Pinus taeda in a Cambissolo Húmico Alumínico léptico (Humic Endo-lithic Dystrudept) in the south of Brazil was studied. A total of 10 trees were sampled distributed in five diameter classes according to diameter at breast height. The biomass of the needles, twigs, bark, wood, and roots was measured for each tree. In addition to plant biomass, accumulated plant litter was sampled, and soil samples were taken at three increments based on sampling depth: 0.00-0.20, 0.20-0.40, 0.40-0.60, 0.60-1.00, 1.00-1.40, 1.40-1.80, and 1.80-1.90 m. The quantity and concentration of nutrients, as well as mineralogical characteristics, were determined for each soil sample. Three scenarios of harvesting intensities were simulated: wood removal (A), wood and bark removal (B), and wood + bark + canopy removal (C). The sum of all biomass components was 313 Mg ha-1.The stocks of nutrients in the trees decreased in the order N&gt;Ca&gt;K&gt;S&gt;Mg&gt;P. The mineralogy of the Cambissolo Húmico Alumínico léptico showed the predominance of quartz sand and small traces of vermiculite in the silt fraction. Clay is the main fraction that contributes to soil weathering, due to the transformation of illite-vermiculite, releasing K. The depletion of nutrients from the soil biomass was in the order: P&gt;S&gt;N&gt;K&gt;Mg&gt;Ca. Phosphorus and S were the most limiting in scenario A due to their low stock in the soil. In scenario B, the number of forest rotations was limited by N, K, and S. Scenario C showed the greatest reduction in productivity, allowing only two rotations before P limitation. It is therefore apparent that there may be a difference of up to 30 years in the capacity of the soil to support a scenario such as A, with a low nutrient removal, compared to scenario C, with a high nutrient removal. Hence, the effect of different harvesting intensities on nutrient availability may jeopardize the sustainability of P. taeda in the short-term.

Nitrogen fixing Cyanobacterial flora of Nadia District in West Bengal, India

Cyanobacteria play an important role in maintenance and build-up of soil fertility, consequently increase rice growth and yield as a natural bio fertilizer. The paddy field ecosystem provides a favourable environment for the growth of Cyanobacteria with respect to their requirement for light, water, temperature and nutrient availability. Continued three successive years (2011 -2014) studied the Occurrence of Cyanobacteria in rice growing fields of Nadia district in West Bengal, India. We survey and studied 3 different rice growing fields of Nadia district namely Haringhata, Kalayani and Jaguliya for studying the cyanobacterial diversity. These rice growing fields mainly comprises unicellular, non-heterocystous and heterocystous cyanobacteria. Total 37 species of Nitrogen fixing Cyanobacteria samples belonging to 21 genera and four orders i.e., Chroococcales, Oscillatoriales, Nostocales, and Stigonematales were isolated from various rice growing localities. Present investigations revealed that the pH range of soil was mostly acidic in Rabi season and it was more than Kharif crop season. Three major Cyanobacterial groups; Unicellular and colonial were slight more than Non-heterocystous i.e., 6 genera and 8 species. Non-heterocystous filamentous cyanobacteria were minimum and its 5 genera and 8 species and heterocystous filamentous cyanobacteria were maximum, its 10 genera and 19 species were occurrence in most of all low and upland rice growing areas.

Litterfall and nutrient return along a disturbance gradient in a tropical montane forest

Litterfall plays an important role in nutrient cycling and maintenance of soil fertility in terrestrial ecosystems. Annual and seasonal variation in litterfall have been investigated in various habitats, however, seasonality in nutrient supply is less well documented. We studied litterfall over two years and seasonal litter nutrient input over one year across a tropical disturbance gradient from mature forest to monoculture tea plantation. Total litter production in the mature forests and regenerating forests was not significantly different. However, tea plantations had significantly lower litter production. Total litterfall in forest habitats showed a clear seasonal pattern with a peak during the dry season (Mar.–May), as has been reported for other tropical seasonal forests. Contrary to expectations, there was no significant difference in litter nutrient concentrations across the disturbance gradient, although there was a substantial change in plant species composition. Litter nutrient concentrations also did not vary significantly across seasons, again contrary to our expectations. Thus, nutrient input was driven solely by the seasonal litterfall pattern. Our results suggest that at a landscape scale turnover in species composition linked to anthropogenic disturbance may not always lead to changes in litter quality, presumably because a similar spectra of leaf types may exist across communities. Seasonal litterfall patterns, which have been more commonly studied, may prove a reasonable proxy for nutrient input in forests.

Land-use intensity and soil properties shape the composition of fungal communities in Mediterranean peaty soils drained for agricultural purposes

Anthropogenic effects on soil fungi have been poorly investigated in peaty soils, where they have a crucial role in the maintenance of soil fertility and in the regulation of nutrient cycles. In this study, we assessed the effects of land-use intensification on the composition of fungal communities in Mediterranean peaty soils drained for agricultural purposes. To this end, a continuous maize cropping system was compared with an extensive grassland and an agricultural soil left abandoned for 15 years. Molecular diversity and community composition of total soil fungi and arbuscular mycorrhizal fungi (AMF) were assessed, as well as soil chemical properties potentially responsible for fungal shifts. The relative roles of intensification and soil chemical properties were also quantified by applying variation partitioning analysis. Multivariate analyses show that: (i) land-use intensification shapes the composition of the community of total soil fungi and AMF in soil and roots; (ii) base saturation (Bas Sat) and exchangeable calcium (ExchCa) in soil are the significant soil chemical drivers of the composition of the total soil fungal community; (iii) Bas Sat is the only significant chemical parameter shaping the soil AMF community; and (iv) no soil chemical properties affect root AMF. Based on variation partitioning, which highlights a large overlap between land-use intensification and Bas Sat, we can assert that land-use intensification is well-correlated with Bas Sat in shaping the total soil fungal community composition, as well as the AMF. By contrast, intensification acts as a major driver with respect to ExchCa in shaping the composition of the total soil fungal communities.

Cotton as an entry point for soil fertility maintenance and food crop productivity in savannah agroecosystems–Evidence from a long-term experiment in southern Mali

Given the scarcity of manure and the limited land available for fallowing, cotton cultivation with its input credit schemes is often the main entry point for nutrients in cropping systems of West Africa. In an experiment carried out during 25 years in southern Mali, the crop and soil responses to organic fertilizer (=OF), inorganic fertilizer (=IF), and a combination of both (=OIF) were quantified and compared to a control treatment for a typical cotton-sorghum-groundnut rotation. From 1965 to 1979 (15 years, period 1), fertilizers were only applied on cotton and the control treatment was not fertilized. From 1980 to 1989 (10 years, period 2), the amount of manure applied was split between cotton and sorghum, and inorganic fertilizers were applied to the three crops. Inorganic fertilizers were also applied to plots with cotton and sorghum that were previously unfertilized control treatments.In favorable rainfall seasons maximum yields of fertilized treatments reached ca. 3.5tha−1 in the case of cotton and groundnuts, and ca. 2tha−1 in the case of sorghum. During period 1, cotton yields were steady (ca. 1tha−1) when no fertilizers were added. Cotton yields were 20% higher in the OF and OIF treatments than in the IF treatment. Sorghum and groundnut benefited from residual effects of fertilizer application on cotton leading to a 200% and 50% yield increase respectively compared to the control treatment. During period 2, yields of the three crops were similar across fertilized treatments. Groundnut yields in the OF treatment, and cotton yields in the OF and IF treatments were respectively 45%, 30% and 20% significantly higher than those in the respective control treatments. No added benefit on crop yields was observed from the combined use of inorganic and organic fertilizer. Soil nutrient contents (SOC, N, P, K) did not significantly change in any of the treatments after 25 years. Soil pH decreased in treatments receiving inorganic fertilizer.Despite low level of soil organic matter, crops responded to organic or inorganic fertilization and crop productivity over time was mostly influenced by the interaction between fertilization and rainfall variability. Our results highlight the role of cotton in West African landscapes as an entry point of nutrients via fertilization, which impacts positively on the productivity of the other crops in the rotation. Credit schemes by the cotton company for farmers to purchase fertilizer to which they would otherwise not have access are thus crucial for sustained crop productivity.

ARBUSCULAR MYCORRHIZAL SYMBIOSIS, ECOSYSTEM PROCESSES AND ENVIRONMENTAL CHANGES IN TROPICAL SOILS

Arbuscular mycorrhizal fungi (AMF) are more widely distributed and associate with a wide range of plant species. AMF are keystone organisms that form an interface between soils and plant roots, and are sensitive to changes in soil and plant conditions. They are important microbial symbioses for plants and under conditions of P-limitation and are significant in the maintenance of soil health and fertility. AMF are crucial for the functioning of terrestrial ecosystems and plants form symbiotic interactions with AMF and colonize more than 80% of plant roots. Mycorrhizal fungi are known to influence plant diversity patterns in a variety of ecosystems globally. AMF hyphae form an extensive network in soil and length is a common parameter used to quantifying fungal hyphae. The mycelial network of AM fungi extends into the soil volume and greatly increases the surface area for uptake of immobile nutrients. Also, AM symbioses improve drought tolerance of plants and enhance tolerance of or resistance to root pathogens. Furthermore, networks of AM hyphae play a role in the formation of stable soil aggregates, building up a macroporous structure of soil that allows penetration of water and air and prevents erosion. The functioning of AMF symbiosis is mediated by direct and indirect effects of biotic and abiotic factors of the surrounding rhizosphere, community, and ecosystem. They have great potential in the restoration of disturbed land and low fertility soil. Little is known about the effects of environmental changes on AMF abundance, activity and the impact on ecosystem services. Also, we still have much to learn regarding the extent of mycorrhizal fungal diversity. It is critical to gain a clearer understanding of functional variation among AM fungal species to guide conservation and restoration efforts.

English

The potency and competitive ability of indigenous rhizobia population in soil to nodulate a non-native legume host has been contentious especially in tropical Africa. This study examined the symbiotic compatibility between the indigenous rhizobia population and a non-native legume species. Soil samples were randomly collected with soil auger at 0 - 30 cm depth from agricultural fields southeast, Nigeria. The control soil samples were obtained from the Badagry beach which had no previous history of legume cultivation at the same depth. Mucuna pruriens seeds were aseptically sown in plastic pots containing these soils kept in the greenhouse for 10 weeks. The test pots were watered with sterile distilled water while the control pots received inorganic nitrogen (N) &nbsp;as source of N nutrient. The agronomic features of the host legume were evaluated after 10 weeks and the presence of appropriate Rhizobium inoculant contributed positively to biomass production in M. pruriens. The Mucuna microsymbiont was found to thrive under favorable climatic and edaphic factors for effective nodulation of the host legume. The microsymbiont was identified on yeast-extract mannitol salt agar (YEMA) containing bromothymol blue (BTB) as Bradyrhizobium and Rhizobium species. This study convincingly showed the importance of rhizobia to soil fertility maintenance in sustainable agricultural practice as well as the adaptability of the legume microsymbiont to different ecological zones particularly the tropical humid environment. &nbsp; Key words: Inoculation, Mucuna pruriens, nodulation, organic agriculture, Rhizobium, soil fertility.

Lentil (Lens Culinaris Medikus) Current Status and Future Prospect of Production in Ethiopia

Lentil is among the oldest domesticated crop in the world. It is a cool season food legume playing a significant role in human and animal nutrition as well as soil fertility maintenance. It can be grown in rotation to cereal crops which promote sustainable cereal-based production systems with a potential of fixing free nitrogen reached up to 107 kg ha-1. It is the most important crop because of its high protein content and fast cooking characteristic. The major lentilgrowing countries are Canada, India, Turkey, Australia, USA, Nepal, China, and Ethiopia. Lentils have an indeterminate growth habit and flowering begins from the lowest branches, gradually moving up the plant and continuing until harvest. It is well adapted to various soil types and also considered as drought-resistant crop. But it is susceptible to excessive water stress. World lentil production has been increasing in recent years with most of the production coming from North American and Asian countries. Productivity of lentil in Ethiopia varies from region to region due to variation in environment and biotic factors. Currently, lentil is considered as a cash crop that fetches higher price compared to most of the cereals and pulses grown in Ethiopia. It is often claimed that, the internal (local) market seriously competes with the external market. Lentil has huge potential of reducing poverty and contributes to sustainable economic development in Ethiopia. Despite the country’s potential and sustained development efforts to get the pulse sub-sector moving, the competitiveness of lentil and hence its contribution to economic development is threatened by low productivity and inconsistent supply of products that does not met both export quality and quantity. On the other hand, the ever increasing population and ever changing client demand of lentil is the good opportunity for boosting production at farm level. In Ethiopia, lentil has received little attention in research, development and external fund attraction. Thus, it is essential to work with federal and regional seed enterprises, farmers’ cooperatives, unions, and seed producing farmers with involvement of private sectors in a coordinated manner to ensure adequate supply of locally certified seeds. It is also necessary to develop recommendations for organic and inorganic fertilizers that are most suitable for lentil production. These recommendations will depend on soil maps and controlled trials of blended fertilizers to determine the optimal balance of macro- and micronutrients. Providing of effective extension service is inevitable to break the existing resistance by awareness creation through demonstration at farmers training centers. Complementary lentil technologies including tillage frequency, seed treatment, planting techniques, genetically improve seed, pests and weed management practices have to be provide to boost production. Indeterminate growth habits of lentil makes not to mature at the same time and brought sever shattering problems before harvest. Harvesting while it is still green is recommended as one option to reduce shattering. Research on the development and promotion of tools (harvester) that would enable farmers to harvest lentil on time is important. Increasing farmers’ access to price information, increase the transparency of the market and would enable farmers make better selling decisions and provide increased bargaining power. The establishment of strong linkage among producers, suppliers, consumers, processors, whole sellers, and retailers is inevitable to begin value chain. A review has been made for boosting production and creating the demand for the use of improved technology keeping in view the enormous contribution of lentil for food and nutritional security.

Effect of Various Organic Manures on Chlorophyll Content and Leaf Surface Area of Guar

Guar (Cyamopsis tetragonoloba L.) is an upright, deep rooted plant of family Leguminosae (Fabaceae), highly valued for its yield, nutritional importance and drought tolerance. Due to increasing cost of chemical fertilizers and its adverse impact on soil, using organic amendments is an alternative method for the improvement of crop production and soil fertility maintenance. The humic substance in organic manure helps in development of plant roots and this in turn helps plants in drawing water as well as other nutrients from the soil. In the present study, enriched vermicompost treated variety RGC 1003 showed maximum growth, increased number of leaves and leaf surface area when compared to other manurial treatments, while RGC 936 showed maximum growth and number of leaves on enriched vermicompost and leaf surface area showed increase in plants grown on vermicompost. The total chlorophyll content was found maximum in RGC 936 on treatment with vermicompost and in RGC 1003 on treatment with farmyard manure. Value of drought tolerant crop like Guar can thus be enhanced by use of organic manure by farmers.