Tillage Frequency, Soil Compaction and N-Fertilizer Rate Effects on Yield of Teff (Eragrostis Tef (Zucc) Trotter) in Central Zone of Tigray, Northern Ethiopia

In Ethiopia, teff is grown for its grain and straw. There is a dearth of information with respect to plowing, compaction and fertilization on vertisols in central zone of Tigray. Therefore, this study was conducted to determine the effects of plowing frequency, soil compaction and N on teff yields. The experimental design was a split-split plot where main plot was plowing frequency with three levels (once, twice and thrice); sub-plot was compaction with two levels (with and without compaction) and sub-sub plot was N-fertilizer rate with four levels (0kg N/ha, 46Kg N/ha, 69Kg N/ha and 92Kg N/ha). There were three replications. Results showed that plowing frequency had no significant effect on most of the yield components except on tillering when the soil is compacted. Maximum average number of tillers per plant (2.75) was obtained from compacted plots plowed two times. Compaction affected almost all yield and yield components significantly. Higher number of tillers per plant (2.64) from non compacted plots and higher stand cover (about 94%) from compacted plots were found. In addition, maximum biomass (4210.617 kg/ha) and grain (1221.98 kg/ha) yields were obtained from compacted plots due to enhanced soil to seed contact resulting in increased plant population. Nitrogen fertilizer significantly increased grain yield and yield components. Maximum stand cover (94.78%), plant height (92.16cm), panicle length (37.75cm), biomass yield (4724 kg/ha) and grain yield (1387.9 kg/ha) were found from plots receiving 92kgN/ha. Partial budget analysis of N fertilizer rates indicted that higher marginal rate of return (525%) were found by applying 69kg N/ha. It is recommended that farmers use 69kg N/ha so as to get economically feasible returns and yield. Keywords: Compaction, Fertilizer N, Plowing frequency, Teff, Vertisol

Integrated use of fertilizer micro-dosing and Acacia tumida mulching increases millet yield and water use efficiency in Sahelian semi-arid environment

Limited availability of soil organic amendments and unpredictable rainfall, decrease crop yields drastically in the Sahel. There is, therefore, a need to develop an improved technology for conserving soil moisture and enhancing crop yields in the Sahelian semi-arid environment. A 2-year field experiment was conducted to investigate the mulching effects of Acacia tumida pruning relative to commonly applied organic materials in Niger on millet growth, yields and water use efficiency (WUE) under fertilizer micro-dosing technology. We hypothesized that (1) A. tumida pruning is a suitable mulching alternative for crop residues in the biomass-scarce areas of Niger and (2) combined application of A. tumida mulch and fertilizer micro-dosing increases millet yield and water use efficiency. Two fertilizer micro-dosing options (20 kg DAP ha−1, 60 kg NPK ha−1) and three types of organic mulches (millet straw, A. tumida mulch, and manure) and the relevant control treatments were arranged in factorial experiment organized in a randomized complete block design with four replications. Fertilizer micro-dosing increased millet grain yield on average by 28 %. This millet grain yield increased further by 37 % with combined application of fertilizer micro-dosing and organic mulch. Grain yield increases relative to the un-mulched control were 51 % for manure, 46 % for A. tumida mulch and 36 % for millet mulch. Leaf area index and root length density were also greater under mulched plots. Fertilizer micro-dosing increased WUE of millet on average by 24 %, while the addition of A. tumida pruning, manure and millet increased WUE on average 55, 49 and 25 %, respectively. We conclude that combined application of micro-dosing and organic mulch is an effective fertilization strategy to enhance millet yield and water use efficiency in low-input cropping systems and that A. tumida pruning could serve as an appropriate mulching alternative for further increasing crop yields and water use efficiency in the biomass-scarce and drought prone environment such as the Sahel. However, the economic and social implications and the long-term agronomic effects of this agroforestry tree in Sahelian millet based system have to be explored further

Ubiquitous molecular substrates for associative learning and activity-dependent neuronal facilitation.

Recent evidence suggests that many of the molecular cascades and substrates that contribute to learning-related forms of neuronal plasticity may be conserved across ostensibly disparate model systems. Notably, the facilitation of neuronal excitability and synaptic transmission that contribute to associative learning in Aplysia and Hermissenda, as well as associative LTP in hippocampal CA1 cells, all require (or are enhanced by) the convergence of a transient elevation in intracellular Ca2+ with transmitter binding to metabotropic cell-surface receptors. This temporal convergence of Ca2+ and G-protein-stimulated second-messenger cascades synergistically stimulates several classes of serine/threonine protein kinases, which in turn modulate receptor function or cell excitability through the phosphorylation of ion channels. We present a summary of the biophysical and molecular constituents of neuronal and synaptic facilitation in each of these three model systems. Although specific components of the underlying molecular cascades differ across these three systems, fundamental aspects of these cascades are widely conserved, leading to the conclusion that the conceptual semblance of these superficially disparate systems is far greater than is generally acknowledged. We suggest that the elucidation of mechanistic similarities between different systems will ultimately fulfill the goal of the model systems approach, that is, the description of critical and ubiquitous features of neuronal and synaptic events that contribute to memory induction

Biophysical interactions in tropical agroforestry systems

sequential systems, simultaneous systems Abstract. The rate and extent to which biophysical resources are captured and utilized by the components of an agroforestry system are determined by the nature and intensity of interac-tions between the components. The net effect of these interactions is often determined by the influence of the tree component on the other component(s) and/or on the overall system, and is expressed in terms of such quantifiable responses as soil fertility changes, microclimate modification, resource (water, nutrients, and light) availability and utilization, pest and disease incidence, and allelopathy. The paper reviews such manifestations of biophysical interactions in major simultaneous (e.g., hedgerow intercropping and trees on croplands) and sequential (e.g., planted tree fallows) agroforestry systems. In hedgerow intercropping (HI), the hedge/crop interactions are dominated by soil fertility improvement and competition for growth resources. Higher crop yields in HI than in sole cropping are noted mostly in inherently fertile soils in humid and subhumid tropics, and are caused by large fertility improvement relative to the effects of competition. But, yield increases are rare in semiarid tropics and infertile acid soils because fertility improvement does not offse

Soil Management Practices to Improve Nutrient-use Efficiencies and Reduce Risk in Millet-based Cropping Systems in the Sahel

Low soil fertility and moisture deficit are among the main constraints to sustainable crop yields in the Sahel. A study therefore, was conducted at the ICRISAT Sahelian Center, Sadore in Niger to test the hypothesis that integrated soil husbandry practices consisting of manure, fertilizer and crop residues in rotational cropping systems use organic and mineral fertilizes efficiently, thereby resulting in higher yields and reduced risk. Results from an analysis of variance showed that choice of cropping systems explained more than 50% of overall variability in millet and cowpea grain yields. Among the cropping systems, rotation gave higher yields than sole crop and intercropping systems and increased millet yield by 46% without fertilizer. Rainfall-use efficiency and partial factor productivity of fertilizer were similarly higher in rotations than in millet monoculture system. Returns from cowpea grown in cowpea-millet rotation without fertilizer and the medium rates of fertilizers (4 kg P.ha-1 + 15 kg N.ha-1) were found to be most profitable in terms of high returns and low risk, principally because of a higher price of cowpea than millet. The study recommends crop diversification, either in the form of rotations or relay intercropping systems for the Sahel as an insurance against total crop failure

Use of rainfall indices to analyze the effects of phosphate rocks on millet in the Sahel

Two critical factors that explain low crop productivity in the Sahelian agro-ecozone are inadequate moisture and poor soils, particularly phosphorus (P) deficiency. The purpose of this long-term study was to explore the use of both local phosphate rock (PR) and inorganic P on yields and risk of millet returns under the uncertain rainfall regimes in the Sahel. Using the Standardized Precipitation Index (SPI) and Percent Confidence Limits (PCL) of the mean rainfall, the 10-year experimental period was grouped into rainfall classes. Results showed that the inorganic P fertilizers, that is, single superphosphate and triple superphosphate (SSP+N and TSP) gave the highest average yields. Also, millet yield increased with increasing P rates. However, typical farmers in the Sahel barely use P rates above 20 kg ha-1 in view of the high cost of imported fertilizers. A low application rate of the local PR, 10 kg P ha-1, increased millet yield between 44 and 67%. Stability analysis using yields from 15 farmers fields indicated that the traditional method of growing millet was the least stable (s.e. = 225) and had the lowest yield (314 kg ha-1). Generally, millet responded to P better when the preseason (May-June) were wet than dry, except where the non-acidulated PR (PRA) was applied every year (R2=0.99, P < 0.01) for both dry and wet preseasons. Risk analysis showed that acidulated PR regardless of rates gave the highest millet returns over variable cost of P fertilizer. The study recommends the promotion PR in order to guarantee stable yields and income for small farmers in the Sahel

Pearl millet-based intercropping systems in the semiarid areas of Senegal

Pearl Millet (Pennisetum glaucum (L.) R. Br.) is one of the principal cereal crops grown in the semiarid agroecosystem of Senegal. It usually is cultivated as a monocrop but yields are low because of inappropriate management and erratic rainfall. The objective of this study was to investigate the potential of agronomic practices, cultural methods and application of organic manures in maintaining crop productivity in pearl millet-based intercropping systems. On-farm research was conducted from 1989 to 1995 to evaluate performance of different millet varieties intercropped with grain and forage cowpea (Vigna unguiculata (L.)Walp.) in two ecozones in the peanut zone of Senegal. The treatments imposed on the experimental units comprised of appropriate cultural techniques and application of compost and rock phosphate. The ecozones were the Central North Region (CNR) and the Central South Region (CSR). Mean rainfall in CNR ranges from 300 to 500 mm y-1 and in the CSR it ranges from 500 to 750 mm y-1. High-yielding millet varieties selected were IBV 8004 and Souna3 for the CNR and CSR. Sole-crop yields were higher than intercrop yields for both species but the millet-grain cowpea intercrop association was more productive than sole crops with a Land Equivalent Ratio of more than one. Millet variety IBV 8004 in sole crop as in intercrop association was more stable than was Souna 3. The yield of selected millet varieties increased more than 40% by compost application as compared to the control with no nutrients applied. There was an additional 10% increase in yield when compost was supplemented with rock phosphate. Key Words: Compost, intercrop association, land equivalent ratio, Pennisentum glaucum RÉSUMÉ Le millet (Pennisetum glaucum (L.) R. Br.) est l'un des principaux céréals plantés dans la région agro-écologique semi-aride du Sénégal. Il est souvent cultivé en monocrop mais le rendement est généralement faible à cause de la gestion inappropriée et des pluies érratiques. L'objectif de cette étude était d'évaluer le potentiel des pratiques agronomiques, méthodes de cultures et l'application des matières organiques pour maintenir la productivité dans le système d'interculture basé sur pennisetum glaucum. Des recherches sur champs étaient conduites entre 1989 et 1995 pour évaluer la performance des différentes variétés du millet en combinaison avec le niébé (Vigna unguiculata (L) Walp.) dans deux zones écologiques de la cacahuète au Sénégal. Les traitements imposés sur l'unité expérimentale comprenaient des techniques de cultures appropriées et l'application des compostes et du phosphate des roches. Les zones écologiques étaient la région centrale du nord (RCN) et centrale du sud (RCS). La moyenne pluviométrique dans le RCN rangée entre 300 et 500 mm y-1 et dans le RCS elle range entre 500 et 700 mm y-1. Les varétés du millet à forte rendement sélectionnées étaient IBV 8004 et Souna 3 pour le RCN et RCS. Le rendement associé à la monoculture était élévé pour les deux espèces mais le millet-niébé combiné était plus productive que la monoculture avec un taux de terre équivalent de plus que un. La variété IBV 8004 en monoculture comme en combinaison était plus stable que le Souna 3. Le rendement des variétés de millet sélectionnées augmenta de 40% avec l'application du composte comparées au contrôle sans intrants. Il y avait une augmentation de 10% en rendement quand le composte était ajouté au phosphate des roches. Mots Clés: Composte, interculture, taux de terres équivalentes, Pennisentum glaucum African Crop Science Journal Vol.12(2) 2004: 133-13

Tree species and pruning regime affect crop yield on bench terraces in SW Uganda

Integration of trees on farms may exert complementary or competitive effects on crop yield. This four year study examined novel systems in which Alnus acuminata (alnus), Calliandra calothyrsus (calliandra), Sesbania sesban (sesbania) or a mixture of all three were grown on the degraded upper part of bench terraces in Uganda; beans or maize were grown on the more fertile lower terrace during the short and long rains. Three pruning treatments (shoot, root or shoot+root pruning) were applied to the tree rows adjacent to the crops; shoot prunings were applied as green manure to the woodlot from which they came. Pruning increased survival in calliandra and reduced survival in sesbania; alnus was unaffected. Pruning reduced tree height and stem diameter in alnus, but did not affect calliandra or sesbania. Maize yield adjacent to unpruned calliandra, alnus and sesbania or a mixture of all three was reduced by 48, 17, 6 and 24 % relative to sole maize. Shoot pruning initially sustained crop performance but shoot+root pruning became necessary when tree age exceeded two years; shoot+root pruning increased maize yield by 88, 40, 11 and 31 % in the calliandra, alnus, sesbania and tree mixture systems relative to unpruned trees. Bean yield adjacent to unpruned calliandra, alnus, sesbania and the tree mixture was 44, 31, 33 and 22 % lower than in sole crops and pruning had no significant effect on crop yield. The results suggest that sesbania fallows may be used on the upper terrace without reducing crop yield on the lower terrace, whereas pruning of alnus is needed to sustain yield. Calliandra woodlots appear to be unsuitable as crop yield was reduced even after pruning

Trees improve water storage and reduce soil evaporation in agroforestry systems on bench terraces in SW Uganda

The success of agroforestry in semi-arid areas depends on efficient use of available water and effective strategies to limit tree/crop competition and maximise productivity. On hillsides, planting improved tree fallows on the degraded upper section of bench terraces is a recommended practice to improve soil fertility while cropping continues on the lower terrace to maintain food production. This study examined the influence of tree fallows on soil water content (θ w ) and evaporation (E s ). Alnus acuminata Kunth (alnus), Calliandra calothyrsus Meissner (calliandra), Sesbania sesban L. (sesbania), a mixture of all three species, or sole crops (beans (Phaseolus vulgaris L.) or maize (Zea mays L.)) were grown on the upper terrace. The same sole crops were grown on the lower terrace. Four management regimes (unpruned, root, shoot and root + shoot pruned) were applied to the tree rows adjacent to the cropping area. Neutron probe and microlysimeter approaches were used to determine θ w and E s when the trees were c. 3.5 years old. Sesbania and alnus increased θ w by 9–18 % in the cropping area on the lower terrace but calliandra reduced θ w by 3–15 %. After heavy rain, E s comprised 29–38 % of precipitation in the tree-based treatments and 53 % under sole crops. Absolute values declined as rainfall decreased, but E s as a proportion of rainfall increased to 39–45 % in the tree-based treatments and 62 % for sole crops. Root + shoot pruning of alnus and the tree mixture increased θ w in the cropping area but had no significant effect in the other tree-based treatments. The results suggest that sesbania and alnus can be planted on smallholdings without compromising water supply to adjacent crops, whereas calliandra decreased water availability despite reducing E s . These results provide a mechanistic understanding of reported effects on crop yield in the same site