Growth and yield responses of cowpea genotypes to soluble and rock P fertilizers on acid, highly weathered soil from humid tropical West Africa

Soils in tropical regions have inadequate levels of phosphorus and this apparently leads to reduced cowpea yield in Africa. Identifying phosphorus-efficient cultivars have the potential to reduce the demand for phosphorus fertilizer and increase the productivity of cowpea. This study was conducted to identify cowpea genotypes that maintain high yields under low soil phosphorus condition. A green-house experiment was conducted at the International Institute of Tropical Agriculture, Ibadan, Nigeria. Fifteen cowpea genotypes were used with two sources of phosphorus fertilisers: rock phosphate (60, 90 and 120 mg P kg−1 soil) and mono potassium phosphate (30, 60 and 90 mg P kg−1 soil) and compared to the control. The experiment was laid out in a strip plot arrangement with three replications. The findings suggested that large geneticvariability exist among the tested cowpea genotypes. IT90K-59 was identified as best phosphorus responder genotype for biomass production and IT90K-76 for grain yield at a rate of 60 mg P kg−1 soil as mono potassium phosphate. Danila and IT89KD-288 were identified as promising genotypes under no or minimal external P application. Five genotypes were identified as good responders to rock phosphate based on their grain yield production. The differential response of the genotypes to low soil phosphorus implies that these traits warrant effective selection for further improvement. Thus, identifying genotypes that can grow well in low phosphorus condition has the potential to reduce the quantity of mineral fertilizersand cost of production.© 2016 International Formulae Group. All rights reserved.Keywords: Rock phosphate, mono potassium phosphate, Alfisol soi

Assessing tree effect on total soil carbon in agroforestry parklands systems along a rainfall gradient in Burkina Faso (West Africa)

Trees contribution in improving soil carbon is well established, but few works addressed how this was affected by a climatic gradient. This research investigated effects of Vitellaria paradoxa C. F Gaertn and Parkia biglobosa (Jacq.) Benth on total soil carbon in parklands along a rainfall gradient for recommendations of tree species which better improve soil carbon under specific climatic conditions for parklands adaptation to climate change. Total soil carbon at topsoil and subsoil layers measured using spectrophotometry infrared method, was higher when rainfall increased and were respectively (1.598 ± 0.040; 1.033 ± 0.022; 0.834 ± 0.014; 0.857 ± 0.016%). It was higher at topsoil (0.529 ± 0.015%) and subsoil (0.282 ± 0.019%) under V. paradoxa when rainfall decreased while it was higher under P. biglobosa and V. paradoxa when rainfall increased slightly. Its improvement was higher under V. paradoxa and P. biglobosa when rainfall respectively decreased and increased. A decrease trend of total soil carbon under both tree species from trunk to outside the canopy whatever rainfall levels and soil layers was observed. Tree species choice could play an important role in improving total soil carbon and crop productivity according to rainfall level for parklands adaptation to climate change

Spatial and temporal patterns of agrometeorological indicators in maize producing provinces of South Africa

Climate change impacts on maize production in South Africa, i.e., interannual yield variabilities, are still not well understood. This study is based on a recently released reanalysis of climate observations (AgERA5), i.e., temperature, precipitation, solar radiation, and wind speed data. The study assesses climate change effects by quantifying the trend of agrometeorological indicators, their correlation with maize yield, and analyzing their spatiotemporal patterns using Empirical Orthogonal Function. Thereby, the main agrometeorological factors that affected yield variability for the last 31 years (1990/91-2020/21 growing season) in major maize production provinces, namely Free State, KwaZulu-Natal, Mpumalanga, and North West are identified. Results show that there was a significant positive trend in temperature that averages 0.03-0.04 degrees C per year and 0.02-0.04 degrees C per growing season. There was a decreasing trend in precipitation in Free State with 0.01 mm per year. Solar radiation did not show a significant trend. Wind speed in Free State increased at a rate of 0.01 ms(-1) per growing season. Yield variabilities in Free State, Mpumalanga, and North West show a significant positive correlation (r > 0.43) with agrometeorological variables. Yield in KwaZulu-Natal is not influenced by climate factors. The leading mode (50-80% of total variance) of each agrometeorological variable indicates spatially homogenous pattern across the regions. The dipole patterns of the second and the third mode suggest the variabilities of agrometeorological indicators are linked to South Indian high pressure and the warm Agulhas current. The corresponding principal components were mainly associated with strong climate anomalies which are identified as El Nino and La Nina events.Peer reviewe

Modeling Approaches to Assess Soil Erosion by Water at the Field Scale with Special Emphasis on Heterogeneity of Soils and Crops

Information on soil erosion and related sedimentation processes are very important for natural resource management and sustainable farming. Plenty of models are available for studying soil erosion but only a few are suitable for dynamic soil erosion assessments at the field-scale. To date, there are no field-scale dynamic models available considering complex agricultural systems for the simulation of soil erosion. We conducted a review of 51 different models evaluated based on their representation of the processes of soil erosion by water. Secondly, we consider their suitability for assessing soil erosion for more complex field designs, such as patch cropping, strip cropping and agroforestry (alley-cropping systems) and other land management practices. Several models allow daily soil erosion assessments at the sub-field scale, such as EPIC, PERFECT, GUEST, EPM, TCRP, SLEMSA, APSIM, RillGrow, WaNuLCAS, SCUAF, and CREAMS. However, further model development is needed with respect to the interaction of components, i.e., rainfall intensity, overland flow, crop cover, and their scaling limitations. A particular shortcoming of most of the existing field scale models is their one-dimensional nature. We further suggest that platforms with modular structure, such as SIMPLACE and APSIM, offer the possibility to integrate soil erosion as a separate module/component and link to GIS capabilities, and are more flexible to simulate fluxes of matter in the 2D/3D dimensions. Since models operating at daily scales often do not consider a horizontal transfer of matter, such modeling platforms can link erosion components with other environmental components to provide robust estimations of the three-dimensional fluxes and sedimentation processes occurring during soil erosion events.Peer reviewe

Aggregation of soil and climate input data can underestimate simulated biomass loss and nitrate leaching under climate change

Predicting areas of severe biomass loss and increased N leaching risk under climate change is critical for applying appropriate adaptation measures to support more sustainable agricultural systems. The frequency of annual severe biomass loss for winter wheat and its coincidence with an increase in N leaching in a temperate region in Germany was estimated including the error from using soil and climate input data at coarser spatial scales, using the soil-crop model CoupModel. We ran the model for a reference period (1980–2010) and used climate data predicted by four climate model(s) for the Representative Concentration Pathways (RCP) 2.6, 4.5 and 8.5. The annual median biomass estimations showed that for the period 2070–2100, under the RCP8.5 scenario, the entire region would suffer from severe biomass loss almost every year. Annual incidence of severe biomass loss and increased N leaching was predicted to increase from RCP4.5 to the 8.5 scenario. During 2070–2100 for RCP8.5, in more than half of the years an area of 95% of the region was projected to suffer from both severe biomass loss and increased N leaching. The SPEI3 predicted a range of 32 (P3 RCP4.5) to 55% (P3 RCP8.5) of the severe biomass loss episodes simulated in the climate change scenarios. The simulations predicted more severe biomass losses than by the SPEI index which indicates that soil water deficits are important in determining crop losses in future climate scenarios. There was a risk of overestimating the area where “no severe biomass loss + increased N leaching” occurred when using coarser aggregated input data. In contrast, underestimation of situations where “severe biomass loss + increased N leaching” occurred when using coarser aggregated input data. Larger annual differences in biomass estimations compared to the finest resolution of input data occurred when aggregating climate input data rather than soil data. The differences were even larger when aggregating both soil and climate input data. In half of the region, biomass could be erroneously estimated in a single year by more than 40% if using soil and climate coarser input data. The results suggest that a higher spatial resolution of especially climate input data would be needed to predict reliably annual estimates of severe biomass loss and N leaching under climate change scenarios.Peer reviewe

Impact of in-field soil heterogeneity on biomass and yield of winter triticale in an intensively cropped hummocky landscape under temperate climate conditions

Crop cultivation provides ecosystem services on increasingly large fields. However, the effects of in-field spatial heterogeneity on crop yields, in particular triticale, have rarely been considered. The study assess the effects of in-field soil heterogeneity and elevation on triticale grown in an intensively cropped hummocky landscape. The field was classified into three soil classes: C1, C2, and C3, based on soil texture and available water capacity (AWC), which had high, moderate, and low yield potential, respectively. Three elevations (downslope (DS), midslope (MS), and upslope (US)) were considered as the second study factor. An unbalanced experimental design was adopted with a factorial analysis of variance for data analysis. Temporal growth analysis showed that soil classes and elevation had significant effects. Generally, better growth was observed in C1 compared to that of C3. DS had a lower yield potential than that of MS and US. In addition, the interactive effect was confirmed, as triticale had poor growth and yield in C3 on the DS, but not on US. Crop physiological parameters also confirmed the differences between soil classes and elevation. Similarly, soil moisture (SM) content in the plow layer measured at different points in time and AWC over the soil profile had a positive association with growth and yield. The results confirmed that spatial differences in AWC and SM can explain spatial variability in growth and yield. The mapping approach combining soil auguring techniques with a digital elevation model could be used to subdivide fields in hummocky landscapes for determining sub-field input intensities to guide precision farming.Peer reviewe

Responses of Upland NERICA Rice to Fertiliser Application and Fallow Management in Different Agro-Ecological Zones of Benin Republic

Recent findings reported that introduction of legumes as an intercrop or in rotation to minimize external inputs can reverse the declining of soil fertility in upland rice agrosystem and so improve the productive capacity of farms. The objectives of the study were to assess (1) the effects of rotation of upland rice with other crops, of fertiliser application and of rice varieties on rice yield and (2) the interaction effects of rotation, fertiliser application and variety on rice production. An experiment was carried out from 2011 to 2012 in 2 zones in Benin Republic, West Africa. Three rice rotation treatments were established where in the year preceding rice cropping the following pre-crops were grown: (1) natural fallow regrowth (2) sole cowpea crop and (3) cowpea/maize intercrop. The following year, 3 NERICA varieties were cultivated in the three pre-crop treatments with and without fertiliser application. With respect to combined effect of NP mineral fertiliser and rotation, a consistent increase in rice yield over all varieties was only observed with maize-cowpea intercrop preceding rice in the Guinean zone. Improved fallow with cowpea combined with fertiliser was beneficial for NERICA 2 and NERICA 4 in the Sudano –Guinean zone and with NERICA 1 and NERICA 4 in the Guinean zone. Rice in rotation with maize-cowpea intercrop and in combination with NP mineral fertiliser can easily fit into the current smallholder farming systems under rain-fed conditions in the Guinean zone, but is not recommendable for the Sudano- Guinean zone

Verbreitung und Biomasseerzeugungspotential von salz beeinflussten Böden in Indien

Die Versalzung des Bodens und Grund-wassers stellt eine der größten Herausforderungen für die Landwirtschaft in ariden und semiariden Gebieten dar. In Folge der Anreicherung von leicht löslichen Salzen, im Wurzelraum, werden die Erträge der Kulturpflanzen signifikant reduziert oder fallen komplett aus. Integrierte Lösungen sind gefragt, die dauerhaft eine nachhaltige, positive Auswirkung auf die Boden-fruchtbarkeit haben und dazu beitragen, das versalzte Ödland wieder nutzbar zu machen. Eine alternative Lösung stellen Agroforstwirtschaftliche Systeme mit multi-funktionalen salz toleranten Baumarten, die eine wesentlich höhere Salztoleranz als die Kulturpflanzen haben, dar. Leguminose Baumarten wie Acacia nilotica und Prosopis juliflora wachsen schnell und können nicht nur als Brennholz oder Baumaterial benutzt werden, sondern auch Hülsenfrüchte tragen, die als Futter oder sogar Nahrung verwendet werden können. Ihre positive ökologische Rolle auf die Bodeneigenschaften, durch Akkumulation von organischer Substanz, Boden-strukturauflockerung und Grundwasser-senkung, ist bekannt. Allerdings ist das Potential des Salzödlandes für die Biomasseerzeugung auf regionaler Skala noch nicht ausreichend erforscht. Im Rahmen des Forschungsprojektes BIOSAFOR, finanziert von der Europäischen Kommission, werden verschiedene Agroforstsysteme für versalzte Böden entwickelt und eine Evaluierung der biophysikalischen Eignung des Ödlandes für die Biomasseproduktion auf Landes- und Staatsebene für Indien durchgeführt. Land Suitability Classification (LSC) der FAO erfolgt auf Staatsebene. Die wichtigsten limitierenden klimatischen, Boden- und Grundwasserparameter werden berücksichtigt, um die Standorteignung für die Biomasseproduktion zu ermitteln