The Potential of Hydro-Climate Forecast Strategies in Sustaining Agricultural Productivity amongst Rainfed Farmers in West Africa: A Review

Several studies have reported a significant yearly decrease in forest cover globally, using satellite images. This is especially true in West Africa, where rapid urbanisation acerbates the problem, and both of these changes lead to alterations in rainfall regime and other changes in climatic parameters. Several studies reveal that adaptation which reduces vulnerability to adverse climatic variation effects is the key to developing resilience against climate change. In this region, over 90% of farmers are engaged in small-scale rainfed crop cultivation and rely on their own weather perception, instincts and what they observe from the surrounding biota (flora and fauna) to forecast the weather and plan their agricultural activities. The pressing nature of the problem of climate variability in Africa had provoked a lot of research into developing and testing several adaptation strategies to control the situation. Various strategies to improve and localize global, regional and national climate services (Local Forecast, Scientific Forecast and Integrated Forecast) needed by the farmers are being developed to build resilience against climate change. This review illustrates the situation in Ghana and identifies various forecast strategies developed to mitigate the adverse effects of climate variability on agricultural productivity. These mitigation methods include the development of climate services to provide users with forecast information in order to make climate-smart decisions to minimize the risk.

Agronomic management practices in dryland wheat result in variations in precipitation use efficiency due to their differential impacts on the steps in the precipitation use process

Yield loss due to low precipitation use efficiency(PUE)occurs frequently in dryland crop production.PUE is determined by a complicated process of precipitation use in farmland,which includes several sequential steps:precipitation infiltrates into the soil,the infiltrated precipitation is stored in soil,the soil-stored precipitation is consumed through transpiration or evaporation,transpired precipitation is used to produce dry-matter,and finally dry-matter is re-allocated to grains.These steps can be quantified by six ratios:precipitation infiltration ratio(SW/SWe;SW,total available water;SWe,available soil water storage at the end of a specific period),precipitation storage ratio(SWe/P;P,effective precipitation),precipitation consumption ratio(ET/SW;ET,evapotranspiration),ratio of crop transpiration to evapotranspiration(T/ET;T,crop transpiration),transpiration efficiency(B/T;B,the increment of shoot biomass)and harvest index(Y/B;Y,grain yield).The final efficiency is then calculated as:PUE=SWe/P×SW/SWe×ET/SW×T/ET×B/T×Y/B.Quantifying each of those ratios is crucial for the planning and execution of PUE improvements and for optimizing the corresponding agronomic practices in a specific agricultural system.In this study,those ratios were quantified and evaluated under four integrated agronomic management systems.Our study revealed that PUE and wheat yield were significantly increased by 8–31%under manure(MIS)or biochar(BIS)integrated systems compared to either conventional farmers’(CF)or high N(HN)integrated systems.In the infiltration and storage steps,MIS and BIS resulted in lower SWe/P but higher SW/SWe compared with CF and HN.Regarding the consumption step,the annual ET/SW under MIS and BIS did not increase due to the higher ET after regreening and the lower ET before regreening compared with CF or HN.The T/ET was significantly higher under MIS and BIS than under CF or HN.In the last two steps,transpiration efficiency and harvest index were less strongly affected by the agronomic management system,although both values varied considerably across the different experimental years.Therefore,attempts to achieve higher PUE and yields in rainfed wheat through agronomic management should focus on increasing the T/ET and SW/SWe,while maintaining ET/SW throughout the year and keeping SWe/P relatively low at harvest time.

Nitrogen and phosphorus fertilization leads to soil arbuscular mycorrhizal fungal diversity changes and rainfed crop yield increase on the Loess Plateau of China:A 37-year study

More than 80%of plants form mutualistic symbiotic relationships with arbuscular mycorrhizal fungi(AMF),and the application of fertilizers,such as nitrogen(N)and phosphorus(P)fertilizers,is a common agricultural management practice to improve crop yield and quality.However,the potential effects of long-term N and P fertilization on the AMF community in the rainfed agricultural system of the Loess Plateau of China are still not well understood.In this study,a long-term field experiment was conducted based on orthogonal design,with three N levels(0,90,and 180 kg ha^(-1)year^(-1))and three P levels(0,90,and 180 kg ha^(-1)year^(-1))for wheat fertilization.Changes in AMF community and correlations between AMF community composition,soil environmental factors,and wheat yield component traits were analyzed using traditional biochemical methods and high-throughput sequencing technology.The results showed that long-term N and P addition had a significant effect on the AMF community structure and composition.Nitrogen application alone significantly reduced the richness and diversity of AMF community,whereas the combined application of N and P significantly increased the richness and diversity of AMF community.The AMF community was driven mainly by soil available P,total P,and pH.There was a significant positive correlation between Glomus abundance and wheat yield and a significant negative correlation between Paraglomus abundance and wheat yield.Long-term N and P addition directly increased crop yield and affected yield indirectly by influencing soil chemical properties and the AMF community.Combined application of N and P both at90 kg ha^(-1)year^(-1)could improve the ecological and physiological functions of the AMF community and benefit the sustainable development of rainfed agriculture.

Index-based assessment of agricultural drought in a semi-arid region of Inner Mongolia, China

Agricultural drought is a type of natural disaster that seriously impacts food security.Because the relationships among short-term rainfall,soil moisture,and crop growth are complex,accurate identification of a drought situation is difficult.In this study,using a conceptual model based on the relationship between water deficit and crop yield reduction,we evaluated the drought process in a typical rainfed agricultural region,Hailar county in Inner Mongolia autonomous region,China.To quantify drought,we used the precipitation-based Standardized Precipitation Index(SPI),the soil moisture-based Crop Moisture Index(CMI),as well as the Normalized Difference Vegetation Index(NDVI).Correlation analysis was conducted to examine the relationships between dekad-scale drought indices during the growing season(May–September)and final yield,according to data collection from 2000 to 2010.The results show that crop yield has positive relationships with CMI from mid-June to mid-July and with the NDVI anomaly throughout July,but no correlation with SPI.Further analysis of the relationship between the two drought indices shows that the NDVI anomaly responds to CMI with a lag of 1 dekad,particularly in July.To examine the feasibility of employing these indices for monitoring the drought process at a dekad time scale,a detailed drought assessment was carried out for selected drought years.The results confirm that the soil moisture-based vegetation indices in the late vegetative to early reproductive growth stages can be used to detect agricultural drought in the study area.Therefore,the framework of the conceptual model developed for drought monitoring can be employed to support drought mitigation in the rainfed agricultural region of Northern China.

Analysis and improving ways for water condition in winter wheat field of dryland in subhumid areas of the Loess Plateau

Based on the soil moisture data from the locating experiments from 1986—1990, and using the water balance method, the water supply and demand state in the field of winter wheat, and the ways for improving water condition in dryland of dry subhumid area of the Loess Plateau were studied. The results suggested that a low precipitation satisfying ratio of 42.9%—58.8% appears in the growing period of winter wheat, and the yield, to a great extent depended on the water that was stored in deep soil layer in the previous rainy season. The filed trial results showed that tillage in the summer fallow period,straw cover, soil moisture regulation with adequate fertilization, crop rotation and proper cropping system could be the efficient ways for improving the water condition,and for the exploitation and utilization of natural water resources(both precipitation and soil water) in the winter wheat field of dryland.

Designing terraces for the rainfed farming region in Iraq using the RUSLE and hydraulic principles

The rainfed region in Iraq comprises an area of more than 5 million ha of forest,grazing and farmland areas.Except the plains,the region suffers from moderate to severe water erosion due mainly to overgrazing and land mismanagement.Due to population growth and the shortage in water resources,an expansion in land used for agriculture in the region is expected.Terracing is an option when utilizing sloping land for agricultural production.A terrace design criterion was developed for the region in which terrace spacing was determined using the Revised Universal Soil Loss Equation(RUSLE);terrace channel specifications were determined using conventional hydraulic computations.Analyses showed that terracing is feasible on rolling and hilly sloping land in the high rainfall zone(seasonal rainfall 4600 mm)where economic crops are grown to offset the high cost of terrace construction and maintenance.In the medium and low rainfall zones(seasonal rainfall 400–600 mm and 300–400 mm),terracing for water erosion control is generally not needed on cultivated land less than 10%in slope where wheat and barley crops are normally grown;however,pioneer research projects are needed to assess the feasibility of terraces of the level(detention)type to conserve rain water in these two zones for a more successful rainfed farming venture.

Land degradation and integrated watershed management in India

In view of the stagnating productivity levels of irrigated agriculture,the contribution from rainfed agriculture should be increased to meet the requirements from the ever growing human and animal population of India.Land degradation is a major threat to our food and environment security and the extent of degradation problems are more pronounced in rainfed regions.Large potential of rainfed agriculture is untapped largely due to lack of enabling policy support and investments.In drought-prone rainfed areas,watershed management has shown the potential of doubling the agricultural productivity,increase in water availability,restoration of ecological balance in the degraded rainfed ecosystems by greening these areas and diversification of cropping farming systems.Impact of various watershed programmes can be substantially enhanced by developing new approaches and enabling policies new paradigm based on learnings over last 30 years for people-centric holistic watershed management involving convergence,collective action,consortium approach,capacity development to address equity,efficiency,environment and economic concerns is urgently needed.However,this can be used as entry point activity for improving livelihood for rural community.It has been realized that for sustainable developments of degraded lands,involvement of people(land less and beneficiaries)is very much essential.For the last decade efforts have been made institutionalize the organizations of the community&beneficiaries and ensuring their involvement in planning project formulation,implementation and maintenance.Government of India has launched various centre-sector,state-sector and foreign aided schemes for prevention of land degradation,reclamation of special problem areas for ensuring productivity of the land,preservation of land resources and improvement of ecology and environment.These schemes are being implemented on watershed basis in rainfed areas.Soil conservation measures and reclamation of degraded lands are decided considering the land capability and land uses.The efforts made so far resulted in enhancement of agricultural production and productivity of lands,increase in employment generation,improving the environment of the areas and socio-economic upgradation of the people.Integrated watershed management approach has been adopted as a key national strategy for sustainable development of rural areas.This has been proved by conducting monitoring and impact evaluation studies of the integrated watershed projects by external agencies.

Double mulching improves soil properties and productivity of maize-based cropping system in eastern Indian Himalayas

A field experiment was conducted for two consecutive years at North Eastern Indian Himalayan region to assess the effect of soil moisture conservation measures on soil and water productivity of different rainfed maize(Zea mays L.)-based cropping sequences.Results revealed that double mulching with in-situ maize stover mulch(MSM)+fresh biomass of white hoary pea(WHP-Tephrosia candida)and MSM+fresh biomass of ragweed(RW-Ambrosia artemisiifolia)improved soil moisture content(SMC)and leaf relative water content of crops during dry season.The soil organic carbon(SOC)content and stocks under MSM+WHP and MSM+RW mulches were significantly higher than that under no mulch at 0-15 cm depth.The soil microbial biomass carbon and dehydrogenase activity were maximum under MSM+WHP/RW.The highest system productivity was obtained from maize-French bean(Pole type-PT)sequence under MSM+RW followed by MSM+WHP.The water productivity was the highest under MSM+WHP.While SOC content was the highest under maize-French bean(PT),the maximum plant available nitrogen and phosphorus were obtained under maize-black gram sequence.Thus,double mulching technology involving MSM and RW(available in plenty)is a viable option for improving soil,crop and water productivity under rainfed hill ecosystems of eastern Indian Himalayas.