Soil Science Collection

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    Evaluation of the impact of alternative wheat residue and water management on soil properties and soybean yield in a wheat-soybean double-crop system, Eastern Arkansas
    (University of Arkansas, 2008-12) Amuri, Nyambilila
    Long-term agricultural sustainability requires evaluation of agricultural management practices that may improve and sustain soil quality and crop productivity over time. The objective of this study was to determine the 6-yr effects of tillage [conventional (CT) and no-tillage (NT)], wheat residue burning (bum and no bum), residue level (low and high), and 3-yr irrigation (irrigated and dry-land condition), on soybean [Glycine max (L.) Men-.] yield, soil physical and chemical properties in the top 10 cm, and weed population diversity in a wheat [Triticum aestivum (L.)]-soybean double-crop production system. A field experiment was conducted from fall 2001 through fall 2007 in the Mississippi River Delta region of eastern Arkansas on a Calloway silt loam (fine silty, mixed, active, thermic Glossaquic Fraglossudalf). Soil bulk density increased at a greater magnitude under NT (1.22 to 1.35 g cm'3) than CT (1.19 to 1.26 g cm*3) during the first 3 years, but declined at a similar rate in both tillage treatments after the third year. Irrigation increased soil pH (0.2 pH unit yr*1), Mehlich-3 extractable soil Mg (55.1 kg Mg ha*1 yr*1), and total C contents (0.11 kg C m*2 yr*1) compared to dry-land condition which had no pH change, but had less increase of extractable Mg (36.6 kg Mg ha*1 yr*1), and total C content (0.04 kg C m*2 yr*1). Soil organic matter (SOM) increased over time in all treatment combinations. Total C (TC) increased at a greater rate in the no bum (0.077 kg C m*2 yr*1) and high-residue-level (0.073 kg C m*2 yr*1) than in the bum (0.051 kg C m*2 yr*1) and low-residue-level (0.054 kg C m*2 yr*1) treatments. The total weed species density was greater under CT (513 plants m*2) than under NT (340 plants m*2) early in the soybean growing season in 2006, but did not differ between tillage treatments in 2007. Perennial weed density was greaterunder bum (99 plants m"2) than no bum (59 plants m’2) in 2006, and in 2007, was greater under NT than CT but unaffected by bum. Retaining crop residues and herbicide application reduced the density of all weed species, grass, and broadleaf weed species. Tillage, burning, and residue level generally did not affect soil penetration resistance in the top 0.20-m in 2003 and in 2006, but soil cone index (CI) was consistently lower under bum than no bum at all depth below 0.20 m. The CI at the 0.05-m depth increased by 35% after 4 years compared to after 1 year of NT soybean. Soybean yield differed over years of the trials. Soybean yield declined during the first 3 years, but increased over the subsequent 3 years in all treatment combinations. Economic analysis showed that management practices with NT will likely be more profitable than the traditional CT practice even when the fertilizer and diesel costs continue to increase. Therefore, NT and non-burning with any residue level have great potential to improve soil quality, reduce weed pressure in the soybean growing season, and maintain profitability in the wheat­ soybean double-crop production system.
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    Human activity spaces and plague risks in three contrasting landscapes in Lushoto district, Tanzania
    (Department of Agricultural Engineering and Land Planning, Sokoine University of Agriculture, P.O. Box 3003, Morogoro, Tanzania, 2014-07-14) Hieronimo, P; Gulinck, H; Kimaro, D. N
    Since 1980 plague has been a human threat in the Western Usambara MountainsinTanzania.However,thespatial-temporal pattern of plague occurrence remains poorly understood.The mainobjectiveofthisstudywastogain understanding ofhumanactivity patterns in relation to spatialdistribution offleasin Lushoto District.Data werecollected in threelandscapesdiffering in plagueincidence.Field survey coupled with Geographic Information System (GIS)and physical sample collectionswereused to collect datainwet(April to June 2012) anddry(August to October 2012)seasons.Dataanalysis was done usingGIS,one-wayANOVAand nonparametricstatistical tools.The degree of spatial co-occurrence of potential disease vectors (fleas) and humans in Lushoto focus differs significantly (p≤0.05)amongthe selected landscapes, and in both seasons.This trend gives a coarseindicationof the possibleassociation of the plague outbreaks and the human frequencies of contacting environments with fleas.Thestudy suggests that plague surveillance and control programmes at landscape scale should consider theexistence of plague vector contagion risk gradientfrom high to low incidence landscapes due to humanpresence and intensity of activities.
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    Climate Impacts on Agricultural and Natural Resource Sustainability in Africa
    (Springer, 2020) Singh, Bal Ram; Safalaoh, Andy; Amuri, Nyambilila A; Eik, Lars Olav; Sitaula, Bishal K; Lal, Rattan
    The major challenge related to sustainable management of natural resources, agricultural and livestock production, and the assessment of innovative technologies and policies is to identify solutions for these problems. Soil degradation, a serious problem in sub-Saharan Africa, is affected by climate change through emission of greenhouse gases (GHGs). Thus, restoration and sustainable management of soil to minimize risks of soil degradation are important to adaptation and mitigation of climate change and to advancing sustainable development goals of the United Nations. Livestock is a source of animal proteins for humans on the one hand and a source of nutrients and energy (biogas) on the other. However, livestock is vulnerable to many climate change-induced disasters such as prolonged droughts and floods, resulting in loss of animals and feed resources. In order to fully benefit from livestock, the targeted interventions needed include adoption of feed preservation technologies, including hay and silage for use during lean periods, controlled planning and management of com- munal grazing areas, rehabilitation of degraded communal grazing areas, and range- lands as a way of improving pasture availability. Research and development priorities and emerging issues include conservation agriculture (CA), use of legume-based crop- ping systems, integrated nutrient management (INM), climate-resilient livestock and feed systems, value addition policies, and adoption of innovative technologies.
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    Report on agronomic practices and soil fertility analysis for improved rice production in the Kilombero and Wami Valley Area in Tanzania
    (USAID & Feed the Future, 2012-11-13) Massawe, B. H. J.
    Tanzanian economy is dominated by smallholder agriculture accounting for more than 90% of rural employment with food crop production dominating the agriculture economy. Rice is the second most important cereal crop in Tanzania after maize and the majority of rice farmers depend on it both for food and cash (Bucheyeki et al., 2011; RLDC, 2011). Tanzania rank second as a largest producer of rice in Southern Africa after Madagascar with production level of 818,000 tons produced from 681,000 ha (USDA world rice statistics, 2007). Like in other food crop production, most of the rice production in Tanzania is undertaken by small scale farming. Small scale rice farming is characterized by many small holder farmers, cultivating small farms (0.5 to 10 acres), whereby rain fed accounts for 71% and traditional irrigation accounts for 29% of rice grown in Tanzania (RLDC, 2011). These small scale farmers use no or low inputs. The major constraints facing the rice production sector includes erratic weather condition and declining land productivity due to application of poor technology, inaccessibility of improved seeds, inherent low soil fertility and poor soil fertility management practices. As a result of these factors the average rice yield per unit area under small scale farms is 1.0 to 1.5 t ha-1. These yields are lower than yield in the developed countries which hikes to over 10 t ha-1 in some seasons (Bucheyeki et al., 2011). To increase rice productivity under small scale farming, identification of gaps between what is recommended for adequate rice production and what is practiced by small scale farmers is required. Most of the current recommendations in soil fertility management in rice fields are blanket. This is not helpful in extension services because as matter of fact, soils are variable and need different packages for their improvements in order to intensify rice production. Therefore, a survey at a somehow detailed scale is important to have area specific recommendations. This report therefore presents: a) Review of current fertilizer and soil management recommendations for rice in the study area; b) Current rice farming practices and their effect on soil fertility depletion in the study area; and c) Site specific soil fertility status and recommendation of measures to be taken in order to improve rice productivity.
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    Report on agronomic practices and soil fertility analysis for improved maize production in Kiteto and Kongwa Districts in Tanzania
    (USAID & Feed the Future, 2012-11-13) Massawe, B. H. J.
    As the pillar of both the domestic and the export economy, the agricultural sector in Tanzania engages about 80 percent of the labor force. The Tanzania’s agriculture economy is dominated by food production which accounts for about 85 percent of over 5 million hectares cultivated per year. Maize is the most important staple food in Tanzania and in the East Africa region in general. In Tanzania, it accounts for 31 per cent of the total food production and constitutes more than 75 per cent of the cereal consumption in the country. The crop is cultivated on an average of two million hectares, which is about 45% of the cultivated area in Tanzania (Katinila et al., 1998). Maize represents about 30 per cent of the value of crop production in the country and 10 per cent of total value added in agricultural sector respectively (Sassi, 2004). The crop provides 60% of dietary calories and more than 50% of utilizable protein to the Tanzanian population. Maize is not only a staple crop in surplus regions but a cash crop as well. About 85% of the maize produced in Tanzania is grown by peasants whose farms are less than 10 ha. Smallholder productivity is very low and highly variable, ranging from 0.01t/ha to 6.77t/ha, averaging 1.19t/ha. This low level of productivity is said to be due to low levels of education, lack of extension services, limited capital, land fragmentation, and unavailability and high input prices (Msuya et al, 2008) Studies carried out by Isinika et al (2003) and MAFC (2006) show that smallholder maize productivity in the country is suffering due to the fact that, most smallholders do not practice high-yield farming methods, and produce mainly for subsistence. The Poverty and Human Development Report of 2007 (R&AWG, 2007) showed that 87 percent of Tanzanian farmers interviewed by the research and analysis group under Tanzania's NSGRP said that they were not using chemical fertilizers; 77 percent said that they were not using improved seeds; 72 percent said that they were not using pesticides, herbicides or insecticides (agrochemicals), due to the high costs of agricultural inputs and services. Kongwa and Kiteto maize farmers are not exceptional. To increase maize productivity under small scale farming, identification of gaps between what is recommended to exploit the production potential and what is practiced by small scale farmers is required. This report covers a work done in maize producing areas of Kongwa district in Dodoma region and Kiteto district in Manyara region of Tanzania. The two districts share a common border. The report is a prelude to a soil test exercise which intends to assist in providing site specific soil fertility status and recommendations for soil and fertilizers management in the identified maize producing areas of Kongwa and Kiteto districts. Specifically, the report covers: a) a review of current fertilizer and soil management recommendations for maize in the study area; b) a review of current maize farming practices and their effect on soil fertility depletion in the study area; c) an analysis of soil variability within the study area in order to establish different sampling units (sites); and d) site specific fertility status and management recommendations for improved maize production based on soil test results.
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    Livestock resources inventory and mapping in agro-pastoral area of Senani, Maswa District, Shinyanga, Tanzania
    (Sokoine University of Agriculture, 2011) Boniface, H.; Massawe, J.; Meliyo, J. L.; Mwilawa, A.; Mashalla, B.
    The agro-pastoralist economy is based on livestock and crop production. The societies practicing agro-pastoralism are equally highly dependent on livestock for their basic food, income and social needs as it is for crop production. The Agro-pastoral production system has developed in semi arid lands and is arguably the best form of land use for these areas. In Senani area where agro-pastoralism is practiced, the agro-pastoralists tend to leave some portions of their land as grazing reserves. The herds of cattle, sheep and goats utilize the forage and water in these grazing reserves only during dry season. This system allows the set aside land to be left free from human activities and livestock grazing during rainy season, which allows natural re-establishment of pasture for re-use in the next dry season. The sizes of the herds in Senani are relatively large such that the grazing reserves with their associated water points are by far less sufficient. This necessitates seasonal migration of some of the animals to the wider grazing lands and permanent water sources in nearby and distant areas. The movements of the agro-pastoralists are therefore very much influenced by the size of their herds in comparison to the size of the grazing reserves under their access and the availability of drinking water. They are also influenced by the factors which affect the abundance and performance of the pasture in their grazing reserves such as favourable amount and distribution of precipitation. The movements in search for pasture and water raise a lot of conflicts with other land users especially the crop growers and conservationists. Information on the available livestock resources is very important for development players who would wish to intervene in improving livestock production. It is on that basis that the project on “Contingency Plans for coping with Crisis Situations in Pastoral Areas of Eastern and Central Africa” wanted to get the livestock resource information of Senani area so that it can use it for appropriate planning and implementation of sustainable livestock production and development of general management plans. The information sought by the project included the livestock migration routes, water sources, grazing reserves, livestock market centres and livestock health services. This information could be acquired, processed and presented using GIS operations. To accomplish that goal, the Project Coordinator requested Mr. Boniface H. J. Massawe of Department of Soil Science, Sokoine University of Agriculture, Morogoro, Tanzania to make an inventory and map the aforesaid livestock resources in the agro-pastoral community of Senani in Maswa district, Shinyanga region, Tanzania by using GIS technologies. The field work was carried out between 15 th and 21 st May, 2011.
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    Distribution of invasive plant species Prosopis juliflora (mesquite) in relationship to biophysical factors in Rombo, Mwanga, and Same districts
    (Sokoine University of Agriculture, 2016) Massawe, B. H. J.
    Prosopis juliflora is among aggressive invaders in tropical, arid and semi-arid natural grasslands. This plant which belongs to the Fabaceae family is native to Mexico, South America and the Caribbean, has become established as an invasive weed in many places including Africa ( In many areas where it is not native, the plant was firstly intentionally introduced and planted for soil and water conservation purposes, ornamental, as well as for fuelwood and fodder (Choge et al., 2002; de Souza Nascimentoa, 2014). Its competitive advantage over other vegetation is based on its ability to fix nitrogen and its tolerance against drought and soil saline condition (Felker et al., 1981; Khan et al., 1986; Singh 1996). Its thorniness and bushy habit enable it to quickly block paths and make whole areas impenetrable for human and livestock. P. juliflora tree is 3-12 m tall, with spreading woody cylindrical branches. It is more or less round- or flat-topped with persistent green foliage and somewhat spiny (Burkart, 1976).The plant grows in a wide range of soils - from sandy to clayey soils. It is generally found in areas where water and soil fertility are the principal agents limiting plant growth. Prosopis species are generally cross-pollinated (Simpson, 1977), although some limited self- pollination (4%) has been observed in P. juliflora (Sareen and Yadav, 1987). The tree produces a very large numbers of flowers, but few are fertile with high rates of ovary abortion (Goel and Behl, 1995). Negative impacts of the tree include loss in agricultural and pasture productivity, biodiversity loss due to its suppression power, and deaths of livestock due to eating of the pods produced by the tree (Choge et al., 2002). Its pollen has been identified among the respiratory allergens in tropical countries (Killian and McMichael, 2004; Dhyani et al., 2006). Positive benefits include production of fuelwood, charcoal, timber and sale of the pods to the feed processing industry (Maundu et al., 2009). The tree is also widely planted for soil conservation, hedgerows, and as an ornamental tree (Pasiecznik et al., 2001).This study intended to identify areas already infested with the tree in Rombo, Mwanga, and Same districts; and to relate their spatial distribution with biophysical factors such as soils, lithology, landforms, and agroecological zones.
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    Bringing evidence to bear on negotiating ecosystem service and livelihood trade-offs in sustainable agricultural intensification in Tanzania, Ethiopia and Zambia as part of the SAIRLA program
    (Sokoine University of Agriculture, 2017-05) Massawe, B.; Johaness, N.; Winowiecki, L. A.; Neely, C.
    The Sustainable Intensification of Agricultural Research and Learning in Africa (SAIRLA) Programme is a UK Department for International Development-funded initiative that seeks to address one of the most intractable problems facing small-holder farmers in Africa - how to engage in the market economy and to deliver sustainable intensification of agriculture, that is, which avoids negative impacts on the environment. SAIRLA will generate new evidence to help women and poor African smallholder farmers develop environmentally and financially sustainable enterprises and boost productivity. The research will focus non-exclusively on 6 countries (Burkina Faso, Ethiopia, Ghana, Malawi, Tanzania and Zambia), thus complementing other research efforts in these regions.
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    Feasibility study of green harvest technology in the sugarcane farming in Tanzania, under the accompanying measures sugar protocol (2011 – 13)
    (Ministry of Agriculture, 2017) Massawe, B. H. J.; Mhoro, L.
    Sugarcane is a tall perennial grass of genus Saccharum. Plant remnants and DNA evidence suggest that sugar cane evolved in South East Asia (Horton et al., 2015), and it was domesticated in Papua New Guinea around 8000 BC (Hartemink and Kuniata 1996). Over the years, the crop has been distributed in other parts of the world including India, China, Europe, Caribbean, Australia, New Zealand, South America, North America and Africa by seafarers, traders, crusaders, colonialists and missionaries (Fischer et al., 2008).Sugar cane performs well in tropical and subtropical climates. The most common cultivated species are S. officinarum L., S. barberi, S. sinense and S. edule. Morphologically, the plant is tall, erecting up to 5 or 6 m with multiple stems, normally branching at the base to make tillers. It is composed of four parts: roots, stalk, leaves and efflorescence (DSD, 2013).
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    Distribution of invasive plant species Chromolaena odorata (Siam Weed) in Serengert district
    (Sokoine University of Agriculture, 2016) Massawe, B. H. J.
    Chromolaena odorata, also known as Siam Weed, is an herbaceous to woody perennial invasive plant species that is considered one of the world’s worst weeds. The plant has a bushy habit which forms a very dense thicket about 2 m high. After the first year of growth, the plant develops a strong, woody underground storage organ, which can reach a diameter of 20 cm ( The weed has effective short and long distance dispersal mechanism, jeopardizing pasture and farmlands in the tropical region, including Tanzania (Crutwell McFadyen and Skarrat; 1996; Kriticos et al., 2005; Raimundo et al., 2007). Most of the seeds produced by the plant enter the soil and build up a seed bank which may survive up to 6 years (Waterhouse and Zeimer, 2002). The seeds are generally wind-disseminated but they can also stick to fur, feather and clothes. Siam weed is highly competitive. It has prolific reproduction, fast growth and branching habit, which ensures rapid domination and suppression of other species. Under its very dense canopy thicket, light is scarce and other fast-growing species cannot survive. Slow-growing, shade- tolerant species are regularly bent to the ground by the continuous pressure of the growth of new C. odorata twigs on the upper layer of the thicket (Gautier, 1992b). The plant has a very efficient root system for nutrients absorption (Bennet and Rao, 1968), and allopathic effects may also be involved in suppressing other vegetation (Ambika and Jayachandra, 1980b; Nakamura and Nemoto, 1993). Siam weed is considered as a weed in all perennial crops of the humid tropics, pasture and forestry. Its aggressiveness is much more serious where it is an exotic plant, rather than where it is native. The weed grows in areas with an annual rainfall below 1000 mm, provided the dry season is not too long and it is limited to around 2000 m altitude. It grows on soils ranging from sand dunes to heavy clays (Liggit, 1983), and it is heavily dependent on the availability of light. The weed has a lot of negative impact in grassland and cropland. In low-growing annual and perennial crops, C. odorata can completely overwhelm the crop, whereas in taller crops, as soon as the canopy is closed the weed is no longer a problem. In shifting cultivation, the weedreplaces the natural secondary succession and becomes the dominant fallow species (Slaats, 1995). The weed out competes and causes severe problems in pastures growth (Audru et al., 1988). It has high nitrate content in its leaves leading it to be poisonous to cattle (Sajise et al., 1974). C. odorata can also transmit pathogenic fungi (Oritsejafor, 1986), and act as a host for insect pests including Zonocerus variegatus (Chapman et al., 1986). In regions where there are dry seasons C. odorata can be a fire hazard (Englberger, 2009). The weed’s presence in Serengeti district was first documented in Rung’abure village less than five years ago. Since then, the weed has prevailed and its distribution has been increasing fast to areas which were previously not infested. Both croplands and pastureland are affected, and the magnitude appears to increase rapidly with time. This study intended to establish the extent of the spread of C odorata in the Serengeti District at the time of the study, and relate it to some biophysical factors from existing database.
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    Factors influencing adoption of soil conservation technologies in Tanzania: A case study in Gairo
    (Sokoine University of Agriculture, 1999) Kalineza, H. M. M.; Mdoe, N. S. Y.; Mlozi, R. S. M.
    Factors that influence smallholder farmers’ decision to adopt soil conservation practices were analysed using descriptive statistics and logistic regression model. Data for the study were collected from 114 randomly selected households from four villages in Gairo division. The results of descriptive analysis suggest that farmers who obtained knowledge on soil conservation through extension/training seminars as well as those with secure land ownership are likely to adopt soil conservation technologies. Two broad policy implications emerge from the findings of this study. The first implication is that there is a need to provide extension education that demonstrate relative benefits of various land conservation technologies to stimulate their adoption. The second implication which emerge from the significance of land provides rights of owning land among smallholder farmers. Secure land rights will promote investments on land such as adoption of soil conservation practices.
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    Characterization of some typical soils of the miombo woodland ecosystem of Kitonga Forest Reserve, Iringa, Tanzania: physico-chemical properties and classification
    (Journal of Agricultural Science and Technology, 2014-03-20) Shelukindo, Hassan Bashiru; Msanya, B. M.; Semu, Ernest; Mwango, Sibaway Bakari; Singh, Bal Ram; Munishi, Pantaleo
    Despite the fact that miombo woodland soils have significant implications in global climate change processes, few studies have been done to characterize and classify the soils of the miombo woodland ecosystem of Tanzania. The current study was carried out to map and classify soils of Kitonga Forest Reserve, which is a typical miombo woodland ecosystem, in order to generate relevant information for their use and management. A representative study area of 52 km 2 was selected and mapped at a scale of 1:50,000 on the basis of relief. Ten representative soil profiles were excavated and described using standard methods. Soil samples were taken from genetic soil horizons and analyzed in the laboratory for physico-chemical characteristics using standard methods. Using field and laboratory analytical data, the soils were classified according to the FAO-World Reference Base (FAO-WRB) for Soil Resources system as Cambisols, Leptosols and Fluvisols. In the USDA-NRCS Soil Taxonomy system the soils were classified as Inceptisols and Entisols. Topographical features played an important role in soil formation. The different soil types differed in physico-chemical properties, hence exhibit differences in their potentials, constraints and need specific management strategies. Texture varied from sandy to different loams; pH from 5.1 to 5.9; organic carbon from 0.9 g/kg to 20 g/kg; and CEC from 3 cmol/(+)kg to 24 cmol/(+)kg. Sustainable management of miombo woodlands ecosystem soils requires reduced deforestation and reduced land degradation.
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    Soil organic carbon stocks in the dominant soils of the Miombo woodland ecosystem of Kitonga Forest Reserve, Iringa, Tanzania
    (International Journal of Agricultural Policy and Research, 2014-03-06) Shelukindo, Hassan Bashiru; Semu, Ernest; Msanya, B. M.; Singh, Bal Ram; Munishi, Pantaleo K.T
    Few studies have determined the soil organic carbon (SOC) stocks in the Miombo woodlands ecosystem in Tanzania. Standard field and laboratory procedures were used to evaluate SOC storage in the Miombo woodlands ecosystem of Kitonga Forest Reserve Iringa, Tanzania. A study area of 52 km 2 was selected and ten soil profiles were studied. Representative sampling points were geo-referenced and soil samples collected from natural horizons to the depth of 60 cm. Results show that the total soil organic carbon stocks in soil profiles varied from 19.4 to 28.9 Mg C ha -1 in leptosols; from 45.6 to 80.1 Mg C ha -1 in fluvisols; and from 33.9 to 134.6 Mg C ha -1 in cambisols. The SOC increased significantly (p< 0.05) with increasing elevation, horizon thickness and % clay, but it decreased significantly (p< 0.05) with increasing slope gradient and increasing % sand. The areal distribution of the soil types was 61%, for cambisols, 19% for leptosols, 11% for fluvisols and 9% for natural forest which was not surveyed because of inaccessibility. Proper management of Miombo woodlands would increase the SOC storage and contribute to climate change regulation.
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    Predictor variables for soil organic carbon contents in the Miombo woodlands ecosystem of Kitonga Forest Reserve, Tanzania
    (International Scholars Journals, 2014-05-20) Shelukindo, Hassan Bashiru; Semu, Ernest; Msanya, B. M.; Singh, Bal Ram; Munishi, Pantaleo K.T
    Few studies have established the variables which adequately predict SOC storage in the Miombo woodlands. Multiple regression analysis was used to establish the variables which could predict SOC contents in dominant soils of the Miombo woodlands of Kitonga Forest Reserve, Tanzania. Thirty soil mini- pits located at different elevations across a topographical gradient were selected, geo-referenced, excavated and samples from the natural horizons were collected for physico-chemical analysis. A total of 85 samples were collected, each representing a natural soil horizon. The results indicated that total nitrogen (TN), (P< 0.001, R 2 = 0.97) and TN in combination with calcium (Ca) (P< 0.001, R 2 = 0.99) were important predictor variables of SOC contents. The combination of cation exchange capacity, Zinc, Copper, clay and iron together with TN and Ca predicted well the SOC contents (P< 0.001, R 2 = 0.999). Considering time and cost implications for field and laboratory analysis in predicting SOC stocks, the combination of TN and Ca that predicted the SOC contents by 99% provided equally strong prediction when compared to the combination of all the variables. Thus, proper land management strategies which enhance conservation of TN and Ca in concert would provide adequate prediction of SOC contents in soils.
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    Assessment of nutrient and biomass yield of medium and long duration pigeon pea in a pigeon pea-groundnut intercropping system in Malawi
    (Journal of Sustainable Society, 2013) Phiri, Austin Tenthani; Msaky, John J.; Mrema, Jerome; Kanyama-Phiri, George Yobe; Harawa, Rebbie
    Preliminary assessment of the performance of the medium and long duration pigeon pea in a pigeon pea- groundnut intercropping system was conducted at Chitedze Agricultural Research Station (S 13 0 59’ 23.2”, E033 0 38’ 36.8”) in the 2011/2012 cropping season. An experiment involving eight treatments replicated three times in a randomized complete block design was established. Two pigeon pea varieties, long (ICEAP 04000) and medium duration (ICEAP 00557) and groundnut (CG 7) were grown as monocultures and intercrops. The intercrops involved planting either of the pigeon pea varieties with groundnut. Baseline soil data indicate that the soil pH was acid to moderately acid both in the top (mean=5.4-5.7) and the sub soil (mean=5.4-5.6) in all the treatment plots, with mostly low to marginally adequate total nitrogen content both in the top (mean=0.08- 0.14%) and the sub soil (mean=0.09-0.13%). The soil organic carbon content was medium in the top soil (mean=0.9-1.6%) as well as sub soil (mean=1.1-1.6%) across the treatment plots. At the same time soil phosphorus was low to marginally adequate in the top soil (mean=16.8-27.6 mg kg -1 ) and marginally adequate in the sub soil (mean=20.8-25.6 mg kg -1 ), suggesting low soil fertility. The assessment of the above ground groundnut biomass indicate a mean yield range of 479-656 kg ha -1 . While the assessment of the total biomass yield of the pigeon pea varieties indicate a mean yield range of 2,034-2,593 kg ha -1 . In terms of estimated nitrogen yields returned to the soil, the medium duration pigeon pea-groundnut intercrop (mean=50.6 kg N ha -1 ) and the long duration pigeon pea-groundnut intercrop (mean=49.6 kg N ha -1 ) gave significantly (p<0.05) higher yields than by the monocultures of long duration pigeon pea (mean=41.1 kg N ha -1 ) and medium duration pigeon pea (mean=41.0 kg N ha -1 ). Statistically (p<0.05), the lowest amount of estimated nitrogen yield was generated by the groundnut sole crop (mean=12.8 kg N ha -1 ). Overall, the intercrops showed yield advantage (total LER >1.0) compared with the monoculture on equal land area. For the Malawian smallholder farmers, this suggests that mineral N supplementation in a legume-cereal rotation system for enhanced crop productivity might be less in the double legume-cereal rotation mode than in a legume monoculture-cereal rotation system.
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    Soil loss due to crop harvesting in Usambara Mountains, Tanzania: the case of carrot, onion and potato
    (SCIENCEDOMAIN international, 2014-09-06) Mwango, Sibaway Bakari; Msanya, B. M.; Mtakwa, Peter W.; Kimaro, D. N.; Deckers, J.; Poesen, J.; Lilanga, S.; Sanga, R.
    Among the various soil erosion processes threatening sustainable agriculture, soil losses due to root, tuber and bulb harvesting are poorly documented, particularly in tropical environments. A study was thus conducted in two villages with contrasting agro-ecological conditions on Acrisols and Fluvisols in Western Usambara Mountains, Tanzania. The aim was to investigate the mass of soil and nutrients lost and the factors influencing variation of soil loss due to crop harvesting (SLCH) for Carrot (Daucus carrota), Onion (Allium cepa L.) and Potato (Solanum tuberosum L.) under low input agriculture. A total of 108 farm plots were sampled from the two villages. The mean SLCH values were significantly higher for carrot (7.1 Mg/ha/harvest) than for onion (3.8 Mg/ha/harvest) than for potatoes (0.7 Mg/ha/harvest). Soil nutrient losses in kg/ha/harvest were higher for carrot than for onion and potatoes (e.g. 30 N, 0.1 P, 1.5 K for carrot vs 6.3 N, 0.04 P, 0.2 K for onion) in Majulai village. SLCH was greater in Migambo (humid cold) than in Majulai (dry warm) for all the studied crops. Soil water content at harvest time played a significant (P = .05) role in inducing SLCH for onion while bulk density for carrot, whereas for potato they were not significantly influenced by soil water content and bulk density. Soil texture played only a minor role to SLCH of the studied crops. The observed soil and nutrient losses in the current study are substantial and pose a challenge that calls for immediate attention to the harvesting practices in the study area. However, combating water erosion is far more urgent.
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    Soil fertility and crop yield variability under major soil and water conservation technologies in the Usambara Mountains, Tanzania
    (SCIENCEDOMAIN international, 2014-12-15) Mwango, Sibaway Bakari; Msanya, B. M.; Mtakwa, Peter W.; Deckers, J.; Poesen, J.; Meliyo, J. L.; Dondeyne, S.
    Indigenous soil and water conservation (SWC) technologies such as miraba (rectangular grass strip bounds that do not necessarily follow contours) and micro ridges have been used widely in the Usambara Mountains, Tanzania. However, their strengths and limitations to crop productivity have not been investigated. This study aimed to determine soil fertility and crop yield variability under miraba, micro ridges and bench terraces as a way to explore and compare these SWC technologies. A survey was carried out in Majulai watershed (with Acrisols as dominant soils) which is highly affected by soil degradation due to water erosion. Composite soil samples were collected from 0 - 30 cm depth in upper, middle and lower segments within bench terraces, micro ridges and miraba at the upper, mid and lower slopes of the watershed. Contents of most soil nutrients (e.g. + 2+ 2+ available P, K , Ca and Mg ) and maize grain yields varied significantly (P=.05) between SWC technologies, with the trend: bench terraces > micro ridges >miraba>control (fields with no SWC measures). Similarly under all SWC technologies soil fertility and maize grain yields varied significantly (P=.05) with slope position, showing the trend: lower slopes > mid slopes > upper slopes. Moreover, soil fertility and maize grain yields varied significantly (P=.05) between segments of the studied SWC technologies except for bench terraces. The trends for both soil fertility and maize grain yields were as follows: lower segments > middle segments > upper segments under micro ridges; lower segments > upper segments > middle segments under miraba. These observations call for management strategies and technological adjustments that would reduce pattern and magnitude of spatial variations of soil nutrients and crop yields under miraba and micro ridges for improved crop production in the Usambara Mountains.
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    Root properties of plants used for soil erosion control in the Usambara Mountains, Tanzania
    (SCIENCEDOMAIN international, 2014-08-25) Mwango, Sibaway Bakari; Msanya, B. M.; Mtakwa, Peter W.; Kimaro, D. N.; Deckers, Jozef; Poesen, Jean; Massawe, V.; Bethuel, I.
    Plant roots may have a strong erosion-reducing effect. However, little is known about root characteristics of tropical plants used for erosion control. A study was thus conducted in the Western Usambara Mountains, Tanzania to investigate rooting characteristics of Guatemala grass (Tripsacum andersonii), Napier grass (Pennisetum purpureum) and Tithonia shrub (Tithonia diversifolia), also referred to as wild sunflower, and to evaluate their potential for erosion control. For each plant species, mean root diameter (D), root density (RD), root length density (RLD) and root area ratio (RAR) were assessed for six plants in each species and relative soil detachment rate (RSD) predicted. Mean RD values in the 0 - 0.4 m soil depth for Majulai village and Migambo village respectively 3 3 were 50.9 and 58.6 kg/m for Guatemala grass, 30.4 and 31.3 kg/m for Napier grass and 3 3 22.1 and 23.0 kg/m for Tithonia shrub. RLD values were 35.9 and 45.0 km/m for 3 3 Guatemala grass, 31.3 and 150.0 km/m for Napier grass and 10.5 and 6.4 km/m for -12 -14 Tithonia shrub. Predicted RSD values were 4.43*10 and 1.20*10 for Guatemala -5 -4 -3 -4 grass, 6.10*10 and 2.74*10 for Napier grass and 4.43*10 and 2.24*10 for Tithonia shrub in the 0 - 0.4 m soil depth. The results indicate that Guatemala grass has a higher potential to reduce soil erosion rates by concentrated flow as compared to Napier grass or Tithonia shrub in the 0 - 0.4 m soil depth. These findings have implications on the selection and use of appropriate plants for soil erosion control.
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    The influence of selected soil conservation practices on soil properties and crop yields in the Usambara Mountains, Tanzania
    (SCIENCEDOMAIN international, 2014-12-08) Mwango, Sibaway Bakari; Msanya, B. M.; Mtakwa, Peter W.; Kimaro, D. N.; Deckers, Jozef; Poesen, J.; Nzunda, I.; Ringo, S.
    The Usambara Mountains in Tanzania are severely affected by soil erosion which has led to deterioration of soil properties and reduced crop productivity. Indigenous soil erosion control measures such as miraba which are widely practised in the area have yielded little success. Field plot experiments were laid down in Majulai and Migambo villages from 2011 – 2014 on typical soils of the area (Acrisols). The aim was to single out soil properties developed under the studied soil conservation practices and their impact on crop productivity with reference to maize (Zea mays) and 2+ 2+ + beans (Phaseolus vulgaris). Results showed that total N, OC, available P, Ca , Mg , K and Ph were powerful (P = .05) attributes that discriminated conservation measures. Magnitudes of the discriminating attributes followed the trend: miraba with Tughutu (Vernonia myriantha) mulching >miraba with Tithonia (Tithonia diversifolia) mulching > miraba sole > cropl and with no ‘Soil and Water Conservation’ (SWC) measures (control). Contents ofmicro-nutrients did not differ significantly with SWC measures except for Zn which was significantly (P = .05) lowin the control. Bulk density and available moisture content (AMC) were also strong discriminators of conservation measures. Maize and bean grain yields differed significantly (P = .05)with the trend: miraba with Tughutu > miraba with Tithonia > miraba sole > control in both villages. Crop yields under miraba were a 2 2+ + 2 function of AMC and pH (R = 0.71); AMC, available P, Ca and K (R = 0.89) under miraba with 2+ + 2 Tithonia mulching; AMC, available P, Ca and K (R = 0.90) under miraba with Tughutu mulching. These findings imply that miraba with Tughutu mulching had greater potential in improving soil properties and crop yields than miraba with Tithonia mulching and miraba sole.
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    Effectiveness of selected soil conservation practices on soil erosion control and crop yields in the Usambara Mountains, Tanzania
    (SCIENCEDOMAIN international, 2014-12-16) Mwango, Sibaway Bakari; Msanya, B. M.; Kimaro, D. N.; Mtakwa, Peter W.; Deckers, Jozef; Poesen, Jean; Massawe, I.; Samwel, J.
    Indigenous soil conservation measures such as miraba have been widely used in Usambara Mountains for controlling soil erosion but with little success. On-farm runoff experiments were set from 2011–2014 on Acrisols in Majulai and Migambo villages with contrasting agro-ecological conditions in the Usambara Mountains, Tanzania. The aim was to investigate the effectiveness of miraba and miraba with various mulching materials in reducing runoff, soil and nutrient losses and improving productivity of maize (Zea mays) and beans (Phaseolus vulgaris). Results show that mean annual runoff coefficients (mm mm -1 ) ranged from 0.72 for cropland with no soil conservation measure (control) to 0.15 for cropland with miraba and Tithonia (Tithonia diversifolia) mulching in Majulai village and respectively from 0.68 to 0.13 in Migambo village. Soil loss was significantly (P = .05) higher under control than under miraba with either Tughutu (Vernonia myriantha) or Tithonia -1 -1 mulching e. g. 184 vs. 20 in Majulai and 124 vs. 8 Mg ha year in Migambo village in 2012. The P- factors were significantly (P = .05) higher under miraba sole than under miraba with mulching in Majulai village (0.18 vs. 0.11) and in Migambo village (0.10 vs. 0.05).The annual nutrient losses in kg ha -1 yr -1 were significantly (P = .05) higher under control than under miraba with mulching 367 vs. 37 total N, 0.8 vs. 0.1 P and 14 vs. 4 K for Majulai village; 474 vs. 26 total N, 0.7 vs. 0.1 P and 20 vs. 1.2 K for Migambo village in 2012. Maize and bean yields were significantly (P = .05) higher under miraba with Tughutu mulching than under control (e.g. 2.0 vs. 0.7 Mg ha -1 for maize in Majulai in 2012). Thus miraba with Tughutu mulching is more effective in improving crop yields than miraba with Tithonia and miraba sole.