Rain-fed Cultivation Research Articles

Adaptive Agricultural Strategies for Facing Water Deficit in Sweet Maize Production: A Case Study of a Semi-Arid Mediterranean Region

Maize is a crucial global commodity, which is used not only for food, but also as an alternative crop in biogas production and as a major energy-supply ingredient in animal diets. However, climate change is jeopardizing current maize production due to its direct impact on weather instability and water availability or its indirect effects on regional climate suitability loss. Hence, new areas for sweet maize cultivation should be considered in the future. Therefore, this study focuses on the possibility of producing maize in a challenging environment in Southern Italy considering rainfed cultivation and two irrigation regimes (full and deficit). The experiment was conducted during two subsequent growing seasons under semi-arid Mediterranean climate conditions. The overall results indicated a significant difference in biomass and yield between irrigated and non-irrigated treatments, and between full and deficit irrigation. Sweet maize cultivated under deficit irrigation gained less biomass than under full irrigation and its development and fruit maturation were delayed. Under deficit irrigation, the plants gave lower yields and a higher percentage of the panicle weight consisted of kernels. Irrigation water productivity was higher for deficit than for full irrigated treatment. These findings indicate the feasibility of sweet maize production in semi-arid areas of Southern Italy using adaptive agricultural strategies including deficit irrigation and controlled water stress. Given the importance of maize production, understanding of maize growth and productivity in a challenging environment may support future agricultural programming and thereby contribute e to mitigation of the direct and indirect effects of climate change.

Drought tolerance in popular sunflower hybrids at seedling stage

Drought is a major abiotic stress coupled with high temperature that limits the crop productivity in arid and semi-arid regions. Productivity of sunflower under moisture stress is primarily determined by seed germination and the seedling vigour for appropriate crop stand. Screening hybrids for moisture stress and high-temperature tolerance under field condition has uncertainties of uncontrolled environmental conditions and interaction of biotic and other abiotic stresses. Hence, in the present experiment, 17 popular hybrids were evaluated for moisture stress tolerance at the seedling stage using PEG-induced osmotic stress and; for high-temperature tolerance using temperature induction response (TIR) technique. The study revealed that root growth was affected higher as compared to the shoot growth in both the experiments. The shoot growth was affected higher due to high temperature as compared to the PEGinduced stress. The hybrids NDSH-1012, PSH-1962, RSFH-130, and GK-202 were tolerant to PEG induced moisture stress while, the hybrids KBSH-41, KBSH-44, KBSH-53, and SB-207 were tolerant to high temperature-induced stress. The hybrids, DRSH-1, KBSH-1 and GK-2009 were moderately tolerant for both the stresses. These hybrids are suitable for drought tolerance at seedling level. This study concludes that the evaluation of hybrids for combined stresses (drought and high temperature) would be appropriate than the individual stress in sunflower. Furthermore, hybrids tolerant to stresses at seedling level should be evaluated at later growth stages for confirmation of drought/ heat tolerance and suitable for rainfed cultivation.

Performance of New Superior Variety of Rice and its Feasibility in Rainfed Rice Lowland of South Sumatra

Rainfed lowland has great potential to produce rice in South Sumatra Province. Rice cultivation in such marginal lowland needs technological innovation for sustainable use. This study aimed to analyze the crop performance and farming feasibility of a New Superior Variety (VUB) in rainfed rice cultivation. The study was carried out on 2019/2020 in Tugu Jaya Village, Lempuing District, OKI Regency. It was implemented in a demonstration plot of rice cultivation covering 2 hectares, using Inpari 30 and 43 varieties. The plant spacing was in accordance with 2:1 “jajar legowo” planting system. This was compared to the tile planting system outside the demonstration plot using IR 42 variety, which was planted by the local farmers. The results of observations of plants’ performance one day before harvest showed that the tallest plant was IR 42 (109.1 cm), the most tillers were from Inpari 43 (19.7 tillers), the longest panicle was of IR 42 (25.1 cm) and the highest harvested crop grain production was from Inpari 30 (6.8 tonnes/ha). In terms of business feasibility, judging from the resulting production and financial indicators, all three varieties were suitable for planting in rainfed lowland. Furthermore, of the three varieties, Inpari 30 on MH 2019/2020 was the most feasible, with a break-even price (BEPr) of Rp. 3,983 per kg; break-even production (BEP) of 1,568 kg per hectare; revenue cost ratio (R/C) of 2.39 and Marginal Benefit-Cost Ratio (MBCR) of 6.96.

Stomatal conductivity, canopy temperature and evapotranspiration of maize (Zea mays L.) to water stress in Northeast China

The Northeast China Plain (NECP) is one of the main maize (Zea mays L.) production regions in China but is now subject to drought because of climate change and a rain-fed cultivation system. A two-year experiment was conducted in a typical maize cultivation region in the NECP to investigate the responses of plant physiological factors and evapotranspiration (ET) to water stresses at different growth stages. Results show that the responses of plant physiological factors to water stress can be divided into three levels based on soil water content (SWC) in the main root zone: when SWC was greater than 0.22 cm3/cm3 (equivalent to 62% field capacity (FC)), stomatal conductivity (gs) and ET reached their highest values, and the canopy temperature (Tc) was close to the air temperature; when SWC was within 0.15-0.22 cm3/cm3 (43%-62% FC), the gs and ET decreased, and Tc increased as SWC decreased; and when SWC was lower than 0.15 cm3/cm3 (<43% FC), gs and ET reached their lowest values and Tc was greater than 1.2 times the air temperature. The ratio of canopy temperature to air temperature (RT), is closely related to stomatal conductivity and soil water content, and especially linearly related to crop water stress index (CWSI), and can be used as an alternative to CWSI for evaluating maize water stress because of easily data achieving and simple calculation processes. In a conclusion, RT of 1.2 can be used as an index to identify a severe water stress status, and maintaining SWC greater than 60% FC at the heading and grain-filling stages is important for supporting maize normal ET and growth in the study region. Keywords: water stress, drought indices, canopy temperature, crop evapotranspiration, stoma conductivity, maize, soil water DOI: 10.25165/j.ijabe.20211402.5289 Citation: Liu H J, Gao Z Z, Zhang LW, Liu Y. Stomatal conductivity, canopy temperature and evapotranspiration of maize (Zea mays L.) to water stress in Northeast China. Int J Agric & Biol Eng, 2021; 14(2): 112–119.

Stomatal conductivity, canopy temperature and evapotranspiration of maize (Zea mays L.) to water stress in Northeast China

The Northeast China Plain (NECP) is one of the main maize (Zea mays L.) production regions in China but is now subject to drought because of climate change and a rain-fed cultivation system. A two-year experiment was conducted in a typical maize cultivation region in the NECP to investigate the responses of plant physiological factors and evapotranspiration (ET) to water stresses at different growth stages. Results show that the responses of plant physiological factors to water stress can be divided into three levels based on soil water content (SWC) in the main root zone: when SWC was greater than 0.22 cm3/cm3 (equivalent to 62% field capacity (FC)), stomatal conductivity (gs) and ET reached their highest values, and the canopy temperature (Tc) was close to the air temperature; when SWC was within 0.15-0.22 cm3/cm3 (43%-62% FC), the gs and ET decreased, and Tc increased as SWC decreased; and when SWC was lower than 0.15 cm3/cm3 (<43% FC), gs and ET reached their lowest values and Tc was greater than 1.2 times the air temperature. The ratio of canopy temperature to air temperature (RT), is closely related to stomatal conductivity and soil water content, and especially linearly related to crop water stress index (CWSI), and can be used as an alternative to CWSI for evaluating maize water stress because of easily data achieving and simple calculation processes. In a conclusion, RT of 1.2 can be used as an index to identify a severe water stress status, and maintaining SWC greater than 60% FC at the heading and grain-filling stages is important for supporting maize normal ET and growth in the study region. Keywords: water stress, drought indices, canopy temperature, crop evapotranspiration, stoma conductivity, maize, soil water DOI: 10.25165/j.ijabe.20211402.5289 Citation: Liu H J, Gao Z Z, Zhang LW, Liu Y. Stomatal conductivity, canopy temperature and evapotranspiration of maize (Zea mays L.) to water stress in Northeast China. Int J Agric & Biol Eng, 2021; 14(2): 112–119.

Determination of Effective Weather Parameters on Rainfed Wheat Yield Using Backward Multiple Linear Regressions Based on Relative Importance Metrics

Wheat (Triticum aestivum L.) is the most imperative crop for man feeding and is planted in numerous countries under rainfed conditions in semiarid zones. It is necessary for decision-makers and governments to predict the yield of rainfed wheat before harvest and to determine the effect of the major factors on it. Different methods have been suggested for forecasting yield with various levels of accuracy. One of these approaches is the statistical regression model, which is simple and applicable for regions with scarce data available. Since the weather is the most important factor affecting the production of wheat, particularly in rainfed cultivation, regression models using weather parameters are very common. However, the coefficients of these models are location based and should be determined locally. Therefore, in this research, backward multiple linear regression (BMLR) technique based on relative importance metrics was used to determine the most important effective weather parameters (11 parameters) on rainfed wheat productions in Fars Province, south of Iran, during 2006–2013. The influence of each parameter in the final model was analyzed using the values of LMG relative importance metric. The result indicated that sunshine hours had the biggest LMG (34.73%) and, therefore, was the most effective parameter. Also, among the other considered parameters, rainy days, minimum relative humidity, and average relative humidity with LMG values of 21.97%, 21.69%, and 21.62%, respectively, had the most effects on rainfed wheat yield in the studied area. All parameters except for the sunshine hours positively affected rainfed wheat yield. The most important reason for the significance of these parameters can be the prevailing dry and semidry climate in the southern areas of Iran. The proposed model for determination of weather parameters effects on rainfed wheat could be a great guidance and aid for different stakeholders such as farmers, decision-makers, and governments.

Hybrid Rootstocks for Valencia Sweet Orange in Rainfed Cultivation Under Tropical Savannah Climate

The performance of Valencia sweet orange grafted onto 41 hybrid citrus rootstocks was evaluated for 11 years in rainfed cultivation under tropical savannah climate (Aw type) in Brazil, in addition to three selections of the standard drought-tolerant Rangpur lime and two selections of Sunki mandarin. Drought tolerance, assessed by visual score of leaf wilting, was directly related to the mean fruit yield. Indio and Riverside citrandarins, Tropical Sunki mandarin and the hybrid TSKC &amp;times; CTSW-028 were grouped with the most productive selections of Rangpur lime, all of them inducing large tree size, intermediate fruit production efficiency, and high drought tolerance. The hybrid TSK &amp;times; TR English-CO was similar except by inducing a higher mean soluble solids concentration in the orange juice. A third group of rootstocks induced high yield and drought tolerance, and a mean 30% reduction in tree size that led to high production efficiency, which comprised the hybrids HTR-053, TSKC &amp;times; (LCR &amp;times; TR)-017 and-059, TSKC &amp;times; CTSW-041, LCR &amp;times; TR-001 and San Diego citrandarin. The tree mortality on Rangpur lime selections was as least as 46%, while more than 80% of trees grafted onto the aforementioned rootstocks survived without visual symptoms of citrus sudden death disease or graft incompatibility. The selected hybrids and Tropical Sunki mandarin also induced fruit quality, mainly soluble solids, superior to the Rangpur lime and, therefore, are potential rootstocks for rainfed cultivation of Valencia sweet orange.

Three thousand years of farming strategies in central Thailand

In prehistoric coastal and western-central Thailand, rice was the dominant cultivar. In eastern-central Thailand, however, the first known farmers cultivated millet. Using one of the largest collections of archaeobotanical material in Southeast Asia, this article examines how cropping systems were adapted as domesticates were introduced into eastern-central Thailand. The authors argue that millet reached the region first, to be progressively replaced by rice, possibly due to climatic pressures. But despite the increasing importance of rice, dryland, rain-fed cultivation persisted throughout ancient central Thailand, a result that contributes to refining understanding of the development of farming in Southeast Asia.

Year-to-year crop shifts promote weed diversity in tropical permanent rainfed cultivation

In the past decades, the expansion and modernisation of agriculture in the mountainous areas of Southeast Asia has had severe impacts on biodiversity, as the once species-rich forests were turned into homogeneous fields receiving ample external inputs. A common feature of permanent cropping with annual crops is the frequent change of crop choice, depending on market opportunities or other motives. However, the precise effect of crop shifts on weeds in tropical areas is largely unknown. In this study, we investigated the short-term effect of crop sequences on the diversity of weed communities in smallholder fields of Northern Thailand. Crop choices were upland rice, maize, fallow and young tree plantations with or without intercrop. We counted the number of crop shifts and the number of crops involved during a 3-years period preceding weed sampling. We showed that the number of crop shifts did not affect weed density and biomass. However, herbaceous species number and diversity (measured as Shannon index) increased by 36% and 46% respectively, while herbaceous species dominance decreased by 38%, in fields with yearly crop shifts compared to fields with no shifts in the previous three years. The effect of a particular crop on diversity, or the effect of intercropping with young trees, was weaker. It was likely due to the more variable resources (especially light) in fields with two crop shifts, allowing species with different niches to co-exist. Crop type and frequent crop shifts did not affect shrub and tree species number, diversity or dominance. Some species were strongly associated with fields with no crop shift in the sequence (e.g. the tree Antidesma velutinosum) or to fields with two crop shifts in the sequence (e.g. the herb Centella asiatica, the C4 grass Digitaria radicosa). Overall, this study showed that in this agronomical system, maintaining yearly crop shifts does not significantly affect weed abundance, but supports in-field plant species diversity, which is likely to impact the services provisioned by tropical mountainous agro-ecosystems.

Land-use and cultivation in theetaghasof the Tadrart Acacus (south-west Libya): the dawn of Saharan agriculture?

The hyperarid climate of the central Sahara precludes permanent agriculture, although occasional temporary ponds, oretaghas,as a result of rain-fed flooding of wadi beds in the Tadrart Acacus Mountains of the Libyan Sahara allow the pastoral Kel Tadrart Tuareg to cultivate cereals. Geoarchaeological and archaeological data, along with radiocarbon dating and evidence from rock art, however, suggest a much greater antiquity for the exploitation of these etaghas. The authors propose that the present-day cultivation of etaghas mirrors attempts at flood-recession or rain-fed cultivation by late prehistoric Pastoral Neolithic groups, who first exploited residual water resources to supplement their pastoral subsistence practices.

On-farm rice diversity and farmers’ preferences for varietal attributes in Ayeyarwady Delta, Myanmar

ABSTRACTMyanmar falls within the center of the genetic diversity of many economically important crops, including wild and cultivated rice (Oryza sativa L.). However, the majority of the genetic resources of Myanmar, particularly local varieties, and their distribution remain poorly understood. The present study was conducted to investigate the on-farm varietal diversity and the determinants of farmers’ variety choices in the Ayeyarwady delta in southern Myanmar, specifically for rainfed rice cultivation. Data from 150 randomly selected households, distributed across five townships, were collected through a semi-structured questionnaire. Households were located in three agro-ecological zones based on the predominant water type (fresh, brackish, and saline). The on-farm diversity appeared to be relatively high according to the number of varieties grown by the farmers. In total, 39 varieties were identified within the survey area. Only 34% of the interviewed farmers grew high-yielding varieties (HYVs) at least on a fraction of their land and the likelihood of adoption of HYVs decreased with length of farming experience, education, and soil fertility, but increased with total area sown under rice according to binomial regression model. From a policy perspective for the high adoption of HYVs, the establishment of a product profile for developing new rice varieties should give priority to farmers’ desired attributes and the vital features, such as resistance to environmental stresses or/and preferred qualitative rice properties, rather than solely considering increased yield.

Variations in Soil Chemical Parameters of Long Term Sugarcane Growing Alfisols under Contrasting Cropping Conditions at Sevanagala, Sri Lanka

This study was conducted to determine the variability of soil pH, macronutrients and Na contents in long term sugarcanegrowing Alfisols at Sevanagala, South-East of Sri Lanka. The study site included the entire sugarcane-growing area covering its contrasting cropping systems namely, irrigated and rain-fed cultivation on low humic gley (LHG) and reddish brown earth (RBE) soils, and adjacent undisturbed soils. The mean pH of the two soil types was significantly different and ranged from 4.5 to 9.3. Except some soils under rain-fed cultivation with a pH less than 5.5 in RBE soil and a pH greater than 7.5 in LHG soils, pH in all other soils favoured sugarcane growth. Plant available P content of soils were not significantly different among cropping conditions due to its wide variation. In both cropping systems and soil types there were areas with very low to nondetectable P levels. Exchangeable K content was significantly different between LHG and RBE soils with the latter having a mean concentration of 257 mg/ kg that is favourable for sugarcane cultivation. Though, the mean values are higher than the optimum range, there were K deficient patches in the studied area. Soil exchangeable Ca, Mg and Na contents were low in the study area but were significantly higher in LHG soils than in RBE soils contributing to alkalinity in the former soils especially under rain-fed conditions. The sugarcane-growing soils except LHG under rain-fed conditions showed chemical properties similar to undisturbed soils in the area highlighting their buffered nature despite long-term sugarcane cultivation. This study also emphasised the need for site-specific soil fertility management strategies for the Sevanagala sugarcane growing areas.

Water use inside inland valleys agro-systems in the Dano basin, Burkina Faso

The hydrological behavior of inland valleys agro-systems is investigated in the Dano basin in South-Western Burkina Faso. Four inland valleys, two with irrigation reservoirs, one with contour bunds and the last with drainage canals were monitored during two hydrological years from June 2014 to May 2016 and compared. A set of indicators on their reliability, their productivity and on the impacts on their environment were assessed. The indicators were chosen to allow spatial and seasonal comparison among the schemes. The results showed a rather abundant rainy season in the four schemes allowing the rain-fed cultivation of rice, with more available water in the simply designed schemes. The irrigation frequency inside the reservoir-based schemes is found to affect their efficiency during the dry seasons. As for the productivity, the reservoir-based schemes perform better than the rest because of an improved control of the inflows and drainage system. In terms of impacts, three out of four schemes have low impacts on their downstream users with a drainage ratio over 60%, and 30% for the last one, which depicts also large amounts of unused water, especially for simple designed inland valleys. On the water quality aspects, the concentration of nitrates, nitrites, potassium, and orthophosphates in the four schemes respect the norms for drinking water, due in part to low fertilizer applications, although having a high potential for eutrophication. The study provides technical elements for comparison between different types of inland valley schemes and highlights their impacts on the water cycle.

Effects of different land-use systems (grazing and understory cultivation) on growth and yield of semi-arid oak coppices

The present study examines the extent of negative effects of traditional multiple land-use systems on oak coppices, from a forest management point of view. The study area was located in approximately 10,000 ha of hilly Brant’s oak (Quercus brantii Lindl.) woodlands in the central Zagros Mountains. In the same site-quality class, three land-use systems were compared: simple coppice (Co), coppice in conjunction with small ruminant grazing (CoG), and coppice with understory rain-fed wheat cultivation plus grazing (CoCG). Data on total wood volume of trunk and major branches, and annual ring growth, were collected and analyzed from 74 stands in 15 coppiced woodland patches. The results showed the advantage of Co over CoG and CoCG land-uses by 43 and 60 m3 of mean accumulated wood volume per hectare, respectively. The diameter growth analysis also revealed an annual increase in wood production of trees in Co land-uses over 43 years, with an exception of the recent decade, when growth coincided with a severe drought. Using a back-extrapolation method, the minimum rotation age of woodlands in Co land-use was found to be 23.6 years, 5 and 7 years shorter than those of CoG and CoCG land-uses, respectively. Unlike CoCG, woodlands located in Co and CoG land-use systems demonstrated a high level of agreement with self-thinning rule of − 3/2. Values for the stand density index for coppiced oak woodlands were between more than 1000 for the least disturbed (Co) and less than 400 for the most disturbed woodlands (CoCG). The structure and growth rate of the coppiced oak woodlands were irreversibly disrupted by understory tillage plus grazing and in less extent by grazing alone. It was concluded that ending undergrowth cultivation in semi-arid oak coppices should be addressed as a priority by adopting minimum regulations.

Evaluating the performance of SALTMED model under alternate irrigation using saline and fresh water strategies to winter wheat in the North China Plain.

The effective water management in the North China Plain (NCP) needs a tool to predict winter wheat production due to water quality. A large quantity of brackish water is stored underground in this region, and whether this water can be used properly in agriculture is becoming a crucial issue that is about to be resolved. The SALTMED model is a generic modeling tool for efficient irrigation management strategies, especially for cyclic use of saline and fresh water as well as different water qualities, and it still needs further investigation for alternate irrigation using saline and fresh water at different growth stages of winter wheat. Therefore, the aim of this investigation was to evaluate the performance of SALTMED model and simulate the production of winter wheat grown under different irrigation strategies. Irrigation strategies comprised rain-fed cultivation (NI), fresh and saline water irrigation (FS), saline and fresh water irrigation (SF), saline water irrigation (SS), and fresh water irrigation (FF). Three-year observed data were used for the validations of SALTMED model. The values of evaluation indices of relative error, RMSE, NRMSE, index of agreement (D-index), and R2 between simulated and observed grain yield were 6.8%, 0.8, 10.7, 0.9, and 0.9, respectively. The model results supported and matched the observed data and indicated similar differences among the irrigated and rain-fed treatments. It is concluded that the SALTMED model is able to predict grain yield of winter wheat and its productivity under the alternate irrigation using saline and fresh water and their interaction in the climate condition of the NCP.

Sustaining Yield of Winter Wheat under Alternate Irrigation Using Saline Water at Different Growth Stages: A Case Study in the North China Plain

Brackish water used for irrigation can restrict crop growth and lead to environmental problems. The alternate irrigation with saline water at different growth stages is still not well understood. Therefore, field trials were conducted during 2015–2018 in the NCP to investigate whether alternate irrigation is practicable for winter wheat production. The treatments comprised rain-fed cultivation (NI), fresh and saline water irrigation (FS), saline and fresh water irrigation (SF), saline water irrigation (SS) and fresh water irrigation (FF). The results showed that the grain yield was increased by 20% under SF and FS treatments compared to NI, while a minor decrease of 2% in grain yield was observed compared with FF treatment. The increased soil salinity and risk of long-term salt accumulation in the soil due to alternate irrigation during peak dry periods was insignificant due to leaching of salts from crop root zone during monsoon season. Although Na+ concentration in the leaves increased with saline irrigation, resulting in significantly lower K+:Na+ ratio in the leaves, the Na+ and K+ concentrations in the roots and grains were not affected. In conclusion, the alternate irrigation for winter wheat is a most promising option to harvest more yield and save fresh water resources.

The archaeology and ethnoarchaeology of rain-fed cultivation in arid and hyper-arid North Africa

Abstract

Analysis and Forecasting of the Impact of Climatic Parameters on the Yield of Rain-Fed Rice Cultivation in the Office Riz Mopti in Mali

During the period spanning the 1970s and1980s, countries in the West African Sahel experienced severe drought. Its impact on agriculture and ecosystems has highlighted the importance of monitoring the Sahelian rainy season. In Sahelian countries such as Mali, rainfall is the major determinant of crop production. Unfortunately, rainfall is highly variable in time and space. Therefore, this study is conducted to analyze and forecast the impact of climatic parameters on the rain-fed rice yield cultivation in the Office Riz Mopti region. The data were collected from satellite imagery, archived meteorology data, yield and rice characteristics. The study employed Hanning filter to highlight interannual fluctuation, a test of Pettitt and the standardized precipitation index (SPI) to analyze the rainfall variability. Climate change scenarios under the RCP 8.5 scenario (HadGEM-2 ES) and agroclimatic (Cropwat) model are carried out to simulate the future climate and its impact on rice yields. The results of satellite image classifications of 1986 and 2016 show an increase of rice fields with a noticeable decrease of bare soil. The analysis of the SPI reveals that over the 30 years considered, 56.67% of the rainy seasons were dry (1986-2006) and 43.33% were wet (2007-2015). The modelling approach is applied over 1986-2006 and 2007-2015 periods—considered as typical dry and rainy years—and applied over the future, with forecasts of climate change scenarios in 2034. The results show a decrease in potential yield during dry and slightly wet years. The yields of rain-fed rice will be generally low between 2016 and 2027. Deficits are observed over the entire study area, in comparison with the potential yield. Thus, this situation could expose the population to food insecurity.

Impact of climate on the yield of major tuber crops in Kwara State, Nigeria

Rain fall, maximum temperature, minimum temperature, evaporation, relative humidity, sunshine hours, soil temperature data were obtained from the National Bureau of Statistics (NBS) for a decade (2002 – 2011), while crop yield data for the same period were sourced from Kwara State Agricultural and Development Project (KWADP). Both climatic and crop yield data were analysed using correlation analytical techniques, multiple regression and trend analysis in order to evaluate the impact of climate on the yield of the major tuber crops in Kwara State, Nigeria viz: cassava, yam, and sweet potato. The result obtained shows that the impact of climate on yield is significant (p<0.05) for yam and cassava, however, insignificant (p<0.05) for sweet potato. The implication of this is that climate has a strong linear correlation with yam and cassava within the years under review. Tuber crops yield in the study area can be improved upon by supplementing rain-fed cultivation with irrigation and application of modern agricultural techniques and operations by the farmers. Keywords: Agriculture, climate, tuber-crops, yield, decade, Nigeria

Future soil moisture and temperature extremes imply expanding suitability for rainfed agriculture in temperate drylands

The distribution of rainfed agriculture, which accounts for approximately ¾ of global croplands, is expected to respond to climate change and human population growth and these responses may be especially pronounced in water limited areas. Because the environmental conditions that support rainfed agriculture are determined by climate, weather, and soil conditions that affect overall and transient water availability, predicting this response has proven difficult, especially in temperate regions that support much of the world’s agriculture. Here, we show that suitability to support rainfed agriculture in temperate dryland climates can be effectively represented by just two daily environmental variables: moist soils with warm conditions increase suitability while extreme high temperatures decrease suitability. 21st century projections based on daily ecohydrological modeling of downscaled climate forecasts indicate overall increases in the area suitable for rainfed agriculture in temperate dryland regions, especially at high latitudes. The regional exception to this trend was Europe, where suitability in temperate dryland portions will decline substantially. These results clarify how rising temperatures interact with other key drivers of moisture availability to determine the sustainability of rainfed agriculture and help policymakers, resource managers, and the agriculture industry anticipate shifts in areas suitable for rainfed cultivation.