90 research outputs found
Effects of combining organic materials with inorganic phosphorus sources on maize yield and financial benefits in western Kenya
Response of Maize to Organic and Inorganic Sources of Nutrients in Acid Soils of Kenya
aize yield in Kericho County, Kenya is limited by infertile acidic soils. The effect of
inorganic sources of nutrients and amendments; triple superphosphate (TSP), calcium
ammonium nitrate (CAN) and lime, were compared to a range of organic nutrient sources;
Farmyard manure (FYM) of low and high quality, dried cow dung, goat manure, tithonia
applied as green manure or dried, in a greenhouse and field experiment. Two soils
collected from two farmers’ fields in Sigowet and Litein locations (Hereafter referred to as
Sigowet and Litein) were used in the greenhouse where maize was grown for six weeks
and its biomass yield determined. The treatments that showed promise were used in a
subsequent field experiment where maize was grown to maturity and grain yield
determined. In the greenhouse, maize responded to application of all the sources of
nutrients and amendments, except lime when applied without TSP, on Sigowet’s soil. On
Litein’s soil, maize did not respond to application of lime alone or with TSP, TSP and dried
tithonia. High quality FYM gave the highest increase (136%) in dry matter yields on
Litein’s soil. In the field experiment, goat manure gave the highest grain yield. Maize failed
to significantly respond to either CAN or TSP when applied alone but the application of the
two in combination (TSP + CAN) effected a significant response indicating that both N and
P were deficient in this soil. All the manures, except low quality FYM, gave yields that
were higher or comparable to the standard recommended fertilizer practice (TSP + CAN)
and could be economically attractive substitutes as they are locally available. There was a
poor correlation between dry matter biomass yield in the greenhouse and grain yield in the
field. Extrapolation of greenhouse findings to different fields should therefore be treated
with caution
Effect of organic and inorganic phosphorus sources on maize yields in an acid soil in western Kenya
Maize production in western Kenya is commonly limited by P deficiencies and aluminum
phytotoxicity. Due to high costs of imported fertilizers and lime, focus is now shifting to solutions that utilize local resources. We tested the effect of three inorganic P sources i.e., triple superphosphate (TSP), Minjingu phosphate rock (MPR) and Busumbu phosphate rock (BPR), each applied in combination with two organic materials (OMs) i.e., farmyard manure (FYM) and
Tithonia diversifolia green manure (tithonia), or with urea on soil chemical properties related to soil acidity, P availability and maize yields for three consecutive seasons in western Kenya. The OMs and inorganic P sources were applied to provide 20 and 40 kg P ha-1 respectively in their combination. Where urea was used, the inorganic P sources were applied at 60 kg P ha-1. Maize did not respond to application of TSP, MPR or BPR with urea in the first two seasons. However, after three seasons, maize significantly responded to application of MPR with urea. FYM was
more effective than tithonia in increasing the labile inorganic P pools but it gave lower maize yields than tithonia which was more effective in reducing the exchangeable Al. It appears that the ability of an OM to lower the exchangeable Al is more important inincreasing maize yields than its ability to increase P availability. The effectiveness of the inorganic P sources in increasing maize yields followed the order of their effectiveness in increasing available P, i.e., TSP[MPR [BPR, once Al phytotoxicity was reduced by application of tithonia but the difference between TSP and MPR was not significant. The extra maize yield obtained by the additional 40 kg P ha-1 from the inorganic P sources was, however, in most cases not substantial enough to justify their use. Economic considerations may therefore favour the use of tithonia or FYM when applied alone at 20 kg P ha-1 than when combined with any of the inorganic P sources used in this study at a total P rate of 60 kg ha-1
Micro-Dosing of Lime, Phosphorus and Nitrogen Fertilizers Effect on Maize Performance on an Acid Soil in Kenya
High cost of inorganic fertilizers and lime has precluded their use by smallholder farmers to remedy the problem of soil acidity and infertility in Kenya. To address the problem, we tested a precision technique referred to as micro-dosing, which involves application of small, affordable quantities of inorganic inputs on an acid soil in Busia County, Kenya. Experimental treatments were N-fertilizer (0 and 37.5 kg N ha-1), P-fertilizer (0 and 13 kg P ha-1) and lime (0, 0.77 and 1.55 tons lime ha-1). 37.5 kg N and 13 kg P ha-1 are 50% of the recommended fertilizer rates for maize production in Kenya while 0.77 and 1.55 tons lime ha-1 are 25 and 50% of the actual requirement. Soil chemical changes, maize grain yield and nutrient recovery were determined. Lime and P-fertilizer significantly affected only the top-soil pH, Ca, Mg and available P, while the effects of N-fertilizer were evident on both top- and sub-soil N likely due to its faster mobility than P and lime. Grain P-fertilizer recovery efficiencies were 14 and 16-27% due to 13 kg P and 13 kg P + 0.77-1.55 tons lime ha-1, respectively. N-fertilizer recovery efficiencies were 37 and 42-45% due to 37.5 kg N and 37.5 kg N + 0.77-1.55 tons lime ha-1, respectively. Fertilizers applied to supply 37.5 kg N, 13 kg P and 0.77-1.55 tons lime ha-1 increased grain yield above the control by 134, 39 and 12-22%, respectively, therefore micro-dosing of these inputs can increase maize production on Kenyan acid soils
Phosphorus Sorption and Lime Requirements of Maize Growing Acid Soils of Kenya
In Kenya, maize (Zea mays L.) is mainly grown on acid soils in high rainfall areas. These soils are known for
low available phosphorus (P), partly due to its sorption by aluminium (Al) and iron oxides. The study determined
soil P sorption, lime requirements and the effects of lime on soil pH, Al levels and available P on the main maize
growing acids soils in the highlands east and west of Rift Valley (RV), Kenya. Burnt lime containing 21%
calcium oxide was used. The soils were strongly to extremely acid (pH 4.85-4.07), had high exchangeable Al3+
(> 2 cmol Al kg-1) and Al saturation (> 20% Al), which most maize germplasm grown in Kenya are sensitive to.
The base cations, cation exchange capacity and available P (< 10 mg P kg-1 bicarbonate extractable P) were low,
except at one site in the highlands east of RV indicative with history of high fertilizer applications. Highlands
east of RV soils had higher P sorption (343-402 mg P kg-1) than the west (107-258 mg P kg-1), probably because
of their high Al3+ ions and also the energies of bonding between the soil colloids and phosphate ions. Highlands
east of RV also had higher lime requirements (11.4-21.9 tons lime ha-1) than the west (5.3-9.8 tons lime ha-1).
Due to differences in soil acidity, Al levels and P sorption capacities within and between highlands east and west
of RV, blanket P fertilizer and lime recommendations may not serve all soils equally well.
Keywords: acid soils, phosphorus sorption, lime requirement
Effects of lime, phosphorus and rhizobia on Sesbania sesban performance in a Western Kenyan acid soil
Aluminium (Al) toxicity, phosphorus (P) deficiency and low rhizobia populations limit Sesbania
(Sesbania sesban) performance in tropical acid soils. The study determined the i) indigenous rhizobia
populations that nodulate sesbania and ii) effects of lime (0 and 4 t/ha), P-fertilizer (0 and 60 kg/ha) and
acid tolerant rhizobia (0 and inoculation) on soil and selected sesbania accessions performance in
Western Kenya acid soil. Study site had acid soil, low available P, nitrogen (N) and rhizobia populations
that nodulate Sesbania (146 cells/g soil). Lime increased soil pH, while both lime and P-fertilizer
increased available P. Aluminium toxicity tolerant and P-efficient accessions (SSBSA004, SSUG3,
SSUG4 and SSUG5) had faster growth, higher nodulation, shoot P, and shoot N and response to
treatments than the sensitive one (SSBSA203). After 7 months of growth, SSUG3 had highest shoot
length (306 cm) and dry matter (5.64 tons/ha), hence, most suitable for building poles and fuel wood.
SSUG5 accumulated the highest shoot N (222 kg N/ha) and was therefore, most suitable soil N
replenishment. Thus, in acid P deficient and low rhizobial population soils of Western Kenya, the use of
lime, P-fertilizer, rhizobia inoculation and Al toxicity tolerant Sesbania are important for Sesbania
establishment and growth.
Key words: Rhizobia, Sesbania, soil acidity, aluminum toxicity, lime, phosphorus
Ocrelizumab versus Interferon Beta-1a in Relapsing Multiple Sclerosis
Supported by F. Hoffmann–La Roche
The V471A polymorphism in autophagy-related gene ATG7 modifies age at onset specifically in Italian Huntington disease patients
The cause of Huntington disease (HD) is a polyglutamine repeat expansion of more than 36 units in the huntingtin protein, which is inversely correlated with the age at onset of the disease. However, additional genetic factors are believed to modify the course and the age at onset of HD. Recently, we identified the V471A polymorphism in the autophagy-related gene ATG7, a key component of the autophagy pathway that plays an important role in HD pathogenesis, to be associated with the age at onset in a large group of European Huntington disease patients. To confirm this association in a second independent patient cohort, we analysed the ATG7 V471A polymorphism in additional 1,464 European HD patients of the “REGISTRY” cohort from the European Huntington Disease Network (EHDN). In the entire REGISTRY cohort we could not confirm a modifying effect of the ATG7 V471A polymorphism. However, analysing a modifying effect of ATG7 in these REGISTRY patients and in patients of our previous HD cohort according to their ethnic origin, we identified a significant effect of the ATG7 V471A polymorphism on the HD age at onset only in the Italian population (327 patients). In these Italian patients, the polymorphism is associated with a 6-years earlier disease onset and thus seems to have an aggravating effect. We could specify the role of ATG7 as a genetic modifier for HD particularly in the Italian population. This result affirms the modifying influence of the autophagic pathway on the course of HD, but also suggests population-specific modifying mechanisms in HD pathogenesis
Ethnobotanical, micrographic and pharmacological features of plant-based weight-loss products sold in naturist stores in Mexico City: the need for better quality control
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