Residual Soil Moisture Research Articles

Long-term agricultural performance and climate variability for drought assessment: a regional study from Telangana and Andhra Pradesh states, India

ABSTRACTA novel approach is presented to assess the agriculture performance in the states of Telangana and Andhra Pradesh using long-term fortnightly satellite, meteorological and irrigation data-sets. National Oceanic and Atmospheric Administration (NOAA), Global Inventory Modeling and Mapping Studies (GIMMS) and Normalized Difference Vegetation Index (NDVI) data for the period 1982–2000 were used to study the pattern of anomalies in the NDVI anomalies and Standardized Precipitation Index (SPI) in the agriculture areas to capture the drought events. After hierarchical image classification and field observations, the Moderate Resolution Imaging Spectroradiometer (MODIS) NDVI product was used to generate the cropped area. The deviation of the NDVI (NDVIDev) was used to understand the agricultural growth/stress, variations in the cropped area and per cent fluctuation in space and time. The SPI, derived from the rainfall data pertaining to 2000–2015, was used to determine the distribution of precipitation. The crop area (%) and growth conditions during the different cropping seasons agree well with the prevailing drought conditions. A significant (p < 0.05) relation was found between the NDVI and precipitation in the summer monsoon each year except during excellent summer monsoon year. The seasonal precipitation, residual soil moisture and source of irrigation were also found to have significant (p < 0.05) impacts on the winter and summer crops.

Effect of Balanced Fertilization in Puddled Rice on the Productivity of Lentil in Rice-Fallow System Under Zero Tillage

Lentil (Lens culinaris Medik) predominantly grows under rainfed conditions under residual soil moisture in most of the rice-fallows in India with low productivity. Imbalanced NPK (N1), recommended dose of NPK (N2) and recommended NPK + 10 t ha-1 FYM (N3) were applied in kharif rice (var. IET 4786) through consecutive three years (2011-2013). Two lentil varieties viz. Asha (B-77) and Subrata (WBL-58) were sown after rice under zero tillage conditions keeping standing residues and mulch through utilizing residual moisture and nutrients. Zero tillage with straw mulch (ZT-M) in both lentil varieties conserved 12-20% more water than residue removal (ZT) and 7-10% more than standing residue (ZT-H), respectively. During flowering (60 DAS) surface soil (0-5 cm) of ZT attained 0.8 MPa as compared to 0.2 and 0.1 MPa for ZT-H and ZT-M, respectively. Soils with N3 stored more water and depleted lesser than N2 and N1 which produced higher biomass, leaf relative water content (RWC) and chlorophyll content. Soil thermal variation in ZT-M tends to proliferate root and nutrient uptake that increased 19 and 14% more yield and 25 and 15% more water use efficiency (WUE) than ZT-H and ZT. Both Subrata and Asha performed well under zero tillage conditions. Zero tillage and nutrient management had an effect on soil microbial biomass carbon (SMBC) and dehydrogenase activity as ZT &lt; ZT-H &lt; ZT-M and N3 &gt; N2 &gt; N1. Proper technology with application of zero tillage may explore the possibility of growing lentil crops in rice fallows during postrainy season utilizing carry-over soil moisture and residual soil fertility.Bangladesh Agron. J. 2016, 19(1): 67-79

S.09.01 - Negative symptoms domains: pathways to functional outcome in schizophrenia

This study evaluates the capability of soil water content predicted from remote sensing to indicate the soil/canopy water content at short time and space scale, through comparisons with daily soil moisture data determined in situ, using dielectric devices. Daily aqua moderate resolution imaging spectroradiometer (MODIS) normalized difference vegetation index (NDVI) and the diurnal (daytime and night time) land surface temperature difference (DLST) are employed to retrieving daily volumetric soil moisture content (θ) at Sparta experimental station, during the period June-August, of the years 2010, 2011, 2012 and 2014. Using the concept of apparent thermal inertia (ATI) in the remotely sensed topsoil moisture saturation index, daily θ is obtained from DLST and the volumetric saturated and residual soil moisture content and is compared with the experimental values of volumetric soil moisture content (SM) measured at various depths (10, 20, 30, 40, 60, 80 and 100 cm). Simple relationships are also calibrated between SM and ATI or DLST or NDVI during the years 2010, 2011 and 2014 and are tested for predicting θ, during the year 2012. Especially the three first models predict θ satisfactorily as compared with the measured SM and hence they can offer a considerable guidance in irrigated agriculture and other related fields.

RELAY SOWING OF WHEAT IN THE COTTON–WHEAT CROPPING SYSTEM IN NORTH-WEST INDIA: TECHNICAL AND ECONOMIC ASPECTS

SUMMARYCotton–wheat (CW) is an important cropping system in South Asia. Wheat yields under a conventional CW system are generally lower compared to a rice–wheat system due to delayed seeding. Relay seeding of wheat can help timely sowing, capturing residual soil moisture of last irrigation to cotton, and increase the productivity and profitability of CW system. The field experiment included two Bt-cotton genotypes having different canopy cover (RCH 776 and MRC 7017), two types of relay seeders (RSs) for cotton planted at 67.5-cm and 101-cm row spacing and four types of relay seeding methods (manual broadcast, strip rotor (SR) and zero-till double disc and conventional till). Relay planting of wheat allowed one additional boll picking, which increased seed cotton yield by 12% compared with conventional tillage wheat. Cotton genotypes and RSs had no effect on emergence and yield of wheat. The RSs with SR and zero till double disc furrow openers performed better in terms of wheat emergence and grain yield compared to zero-till tine openers. Under relay seeding, wheat sowing was advanced by 31 days, which increased grain yield by 18.8% compared with conventional tillage practice. Net returns from the CW system with relay seeding of wheat were higher by US$ 311 to 425 ha−1 compared with the conventional CW system.

Evaluation of CropSyst model for clusterbean under hot arid condition

The study on “Evaluation of Cropsyst model for yield and water productivity of clusterbean” was conducted on farmers field during kharif 2012 at village Mainawali in Hanumangarh district of Rajasthan. The soils of the area are alluvial and calcareous in nature formed under arid and semi arid climate. The soils of site are brown to greyish brown and dark grey in colour, besides being calcareous and slightly alkaline in reaction having 67.7, 11.1 and 21.0 % of sand, clay and silt, respectively in 0-15 cm soil depth with pH 8.09 and low soil organic matter content. The simulate yield of clusterbean were closer to the observed clusterbean yield. Simulations of early clusterbean above ground biomass development matched the field data reasonably well. Final above ground biomass, however, was over estimated by the model. The total water applied in clusterbean was 405.8 mm out of this 326.7 mm consumed in ET. Thus, ET constituted 81% of total water applied and deep drainage constituted 13% and rest 6% stored as residual soil moisture.

Effects of stubble length of rice in mitigating soil moisture stress and on yield of lentil (Lens culinaris Medik) in rice-lentil relay crop

Opportunity to utilize carry-over residual soil moisture to produce lentil crop in rice-fallows was one of the basic and strategic research objectives of the present experiment. Lentil (Lens culinaris Medik, variety B-77) was broadcasted upon two rice habits viz. short-duration (SD, 110days) and long-duration (LD, 140days) in the end of October and first fortnight of November during 2011–2012, 2012–2013 and 2013–2014 seasons, in a clay loam Inceptisol of the Gangetic alluvium of eastern India. Two stubbles heights, viz. short (10cm) and long (20cm) were kept as standing residues at the time of harvesting of rice. Late sown lentil with short stubble residues faced surface soil drying earlier than early sown lentil or late sown lentil with tall stubble residues. Tall stubble height contributes only 1–4% higher soil water during vegetative to flowering stages than short stubble height. Stress was experienced when soil moisture content in the root-zone reached <22% in this soil and such stress decreased the leaf relative water content (RWC). Retaining tall rice stubbles on the soil surface decreased daytime soil temperature by 9.4–14.6°C and modified the crop coefficient (Kc) by increasing transpiration and reducing evaporation, thereby maintaining higher leaf area index (LAI). The Kc values for the initial, development, mid and late season stages of lentil under relay cropping were 0.48, 0.54, 0.82 and 0.48, respectively, with short and tall standing stubble heights. Root length density (RLD) values increased at a faster rate in 200–400mm layer, especially in tall stubble than short. Soil moisture stress was negatively related (R2=0.66, P<0.05) to RWC, however, RLD maintained an asymptotic relationship with RWC. Actual evapotranspiration (ETa) of lentil amounted to 154.8mm and the ETa in broadcasted upon SD rice was 14% higher than ETa in LD rice. Lentil in tall stubbles amounted to 150.6mm ETa, which was 7% more than that in short stubbles. Yield of lentil broadcasted upon SD was 20% higher than 20days delay with LD rice, and tall stubbles produced 18% more yield than short stubbles. The water productivity (WP) of lentil under SD rice was only 6% higher than lentil in LD rice; however, tall stubbles produced 11% higher WP than short standing stubbles. Keeping stubbles height of SD or LD rice may be an efficient way of using the existing land and water resources for mitigating soil moisture stress and maintaining grain yield and water productivity of lentil relayed with short- and long-duration rice habits.

Modeling of Hydrological Extremes Under Climate Change Scenarios in The Upper Blue Nile River Basin, Ethiopia

The impact of climate change on modeling of hydrological extremes is needed to asses at regional and local scales since these vicissitudes are not uniform over the globe. This work stresses on climate change impact on the hydrological extremes (MMAX, CMAX, NNHF, Q10, MMIX, CMIX, MIN7, and Q90) and precipitation extremes (MLWD, MLDD, ADMT, ADMP) during the far future (2071-2100) period over the selected sites across the upper Blue Nile River basin (UBNRB), Ethiopia. The change in extreme indices were calculated based on daily precipitation and temperature data derived from the most recent CMIP5 climate projection scenarios compared to the reference period (1971-2000). The raw outputs from the climate models were corrected in order to reduce biases using distribution based quantile mapping technique. The validation and calibration demonstrates that the seasonal maximum cycle of precipitation and temperature in the reference period is reproduced reasonably in the bias-corrected climate results. The projections of climate change impacts on the hydrological extremes were evaluated using three generalize lump conceptual hydrological models: GR4J; HBV; HMETS and two objective functions: NSE and LogNSE. These hydrological models are calibrated in the period of 1971-2000 and validated in 2001-2010 period. The optimized hydrological parameters are adopted for the future hydrological simulations (2071-2100). The results indicate that the wet/dry spell will significantly decrease/increase due to climate change in some sites of the region (sites 2 and 6), while in sites 1 and 5, there is increase/decrease in wet/dry spell but not significant, respectively. Far future maximum river flows in the study area will be less extreme and more variable in terms of magnitude, and more irregular in terms of seasonal occurrence, than they are at present. Low flows may become less extreme and variable in terms of magnitude, and more irregular in terms of seasonal occurrence. Most areas of northern, western, and northeastern part of the river basin will likely become wetter in the wet season and drier in dry season. Whereas, indices that related to low flows are projected to increase most prominently for lowland sites, due to the combined effects of projected decreases in summer precipitation, and projected increases in evapotranspiration that reduce residual soil moisture in late summer. Whereas the indices related to the high flows are projected slight increase in the central and upper part of the basin. According to the evaluated scenarios, climate change may have favorable impacts on the distribution of hydrological extremes in the study area.

Effect of Puddling and Compaction on Water Requirements of Rice at Hamelmalo, Eritrea

Eritrean farmers can cultivate rice by harvesting runoff from >82% available non-agricultural land in agricultural watersheds for crop use and reducing percolation through optimization of tillage. Experiments were conducted with NERICA rice, N11, to optimize irrigation requirements and puddling and compaction to reduce percolation. Experimental field was adjacent to Anseba River at downstream end of the watershed and a pond on the upstream to intercept runoff. Irrigation treatments were runoff farming with maximum runoff application depth of 10 mm (I1), and 50 mm irrigation two (I2), five (I3), and seven (I4) days after disappearance of ponded water in main plots and puddling by one (T1), two (T2) and three (T3) passes of puddler and compaction by three (T4), four (T5) and five (T6) passes of 600 kg roller in sub plots in 3 replications. Soil profile was loam in the surface 0.45 m and coarse sandy loam below forming porous belt. Soil submergence was difficult to maintain, but water table was developed in soil profile due to inflow of seepage from the river and pond. Depth to the water table was within 1.5 ± 0.1 m for >2 months and receded down to 1.7 m by crop maturity. Soil wetness was near field capacity around 0.7 m depth and increased below due to natural sub-irrigation from the water table. Rice roots penetrated 0.8 m in the puddled plots and 0.7 m in the compacted plots. Residual soil moisture of 135 - 146 mm·m-1 after rice harvesting provides opportunity for planting rapeseed mustered following rice. Puddling was superior to compaction in loam soil. Puddling twice and irrigation 50 mm 7 days after ponded water vanished from surface was sufficient for optimum rice grain yield of 4346 kg·ha-1 and straw yield of 4458 kg·ha-1. Optimum puddling and irrigation schedules reduced crop duration by 6 days without significantly affecting yield. Production function showed that rice grain yield of 4789 kg ha-1 could be obtained by 1009 mm applied water through rainfall and irrigation.

Optimizing Tillage and Irrigation Requirements of Sorghum in Sorghum-Pigeonpea Intercrop in Hamelmalo Region of Eritrea

Sorghum (Sorghum bicolor L. Moench) is cultivated as monocrop in Eritrea. Efforts were made to grow sorghum-pigeonpea (Cajanus cajan L. Millspp.) intercrop on the tillage, fertilizers and supplementary irrigations necessary for sorghum. Experiments were conducted in terraced fields at Hamelmalo during 2013-15 to evaluate growth and yield of sorghum-pigeonpea intercrop in split plot design with conventional tillage (CT), reduced tillage (RT) and zero tillage (ZT) in main plots and rainfed (I0), 50% of full irrigation (I1), 75% of full irrigation (I2) and 100% of full irrigation (I3) in subplots. All irrigations were stopped 15 days before sorghum maturity. Full irrigation was 60 mm applied at 50% depletion of available soil water in 1 m profile. Sorghum growth was faster than pigeonpea until 85 days from planting and pigeonpea growth accelerated only after sorghum harvesting. About 80% of sorghum roots were within 0.6 m profile but more than 75% of pigeonpea roots were below 0.60 m depth. This showed a weaker competition between the two crops for nutrients, water and light. Both grain and stover yields of sorghum were optimum in RT + I2 during the 2 years. Highest grain yield was 6900 kg·ha-1 in RT + I3 in 2013, which was at par with that in RT + I2. Mean residual soil moisture at sorghum harvesting was 74 mm·m-1, which decreased to 8 mm·m-1 by pigeonpea harvesting. Residual moisture was more in the irrigated than non-irrigated plots. Pigeonpea yields were optimum (1363 kg·ha-1) in RT + I3 and lowest (297 kg·ha-1) in ZT + I0. Average water use by sorghum-pigeonpea was 374 mm by sorghum harvesting and 438 mm by pigeonpea harvesting, producing total sorghum equivalent yield of 7475 kg·ha-1. This raised average water use efficiency from 12.6 kg·ha-1·mm-1 at sorghum harvesting to 17.1 kg·ha-1·mm-1 at pigeonpea harvesting. Benefit was doubled at 50% of full irrigation and >4 times at 75% of full irrigation.

Assessing effects of soil hydraulic properties on the temporal stability of absolute soil moisture content and soil moisture anomaly under different climatic conditions

Due to the complex interactions of soil moisture with its controlling factors, numerical models are more suitable for quantifying different controls on the temporal pattern of soil moisture. Here, the effects of soil hydraulic properties on the temporal stability of absolute soil moisture content (TS SMC) and soil moisture anomaly (TS SMA) under different climatic conditions were assessed using a vadose zone model. To run the model, two soil datasets with van Genuchten parameters were generated and hydrometeorological data from four study sites with a significant precipitation gradient were obtained. The TS SMC analysis revealed that the patterns of mean relative difference (MRD) and standard deviation of relative difference (SDRD) of soil moisture partly depended on climatic conditions. With increasing precipitation, the range of MRD generally decreased; whereas, the range and mean value of SDRD increased, indicating that soil moisture was temporally more stable under drier climatic conditions. Based on the Spearman rank correlation coefficient, the results showed that the dependence of MRD on soil hydraulic parameters was partly determined by climatic conditions. With decreasing precipitation, the effects of residual soil moisture content, saturated hydraulic conductivity, and the parameter l that accounts for pore tortuosity and connectivity strengthened, while the effects of saturated soil moisture content and the parameter n that is a measure of pore size distribution weakened. Finally, according to the Pearson correlation coefficient, the results revealed that the control of soil hydraulic properties was shown to be reduced in the TS SMA analysis, thus confirming the previously made conjecture that the use of soil moisture anomalies in the temporal stability analysis reduces the impacts of static soil properties.

Prediction of Soil Moisture from Remote Sensing Data

This study evaluates the capability of soil water content predicted from remote sensing to indicate the soil/canopy water content at short time and space scale, through comparisons with daily soil moisture data determined in situ, using dielectric devices. Daily aqua moderate resolution imaging spectroradiometer (MODIS) normalized difference vegetation index (NDVI) and the diurnal (daytime and night time) land surface temperature difference (DLST) are employed to retrieving daily volumetric soil moisture content (θ) at Sparta experimental station, during the period June-August, of the years 2010, 2011, 2012 and 2014. Using the concept of apparent thermal inertia (ATI) in the remotely sensed topsoil moisture saturation index, daily θ is obtained from DLST and the volumetric saturated and residual soil moisture content and is compared with the experimental values of volumetric soil moisture content (SM) measured at various depths (10, 20, 30, 40, 60, 80 and 100cm). Simple relationships are also calibrated between SM and ATI or DLST or NDVI during the years 2010, 2011 and 2014 and are tested for predicting θ, during the year 2012. Especially the three first models predict θ satisfactorily as compared with the measured SM and hence they can offer a considerable guidance in irrigated agriculture and other related fields.

A non-equilibrium model for soil heating and moisture transport during extreme surface heating: the soil (heat–moisture–vapor) HMV-Model Version 1

Abstract. Increased use of prescribed fire by land managers and the increasing likelihood of wildfires due to climate change require an improved modeling capability of extreme heating of soils during fires. This issue is addressed here by developing and testing the soil (heat–moisture–vapor) HMV-model, a 1-D (one-dimensional) non-equilibrium (liquid–vapor phase change) model of soil evaporation that simulates the coupled simultaneous transport of heat, soil moisture, and water vapor. This model is intended for use with surface forcing ranging from daily solar cycles to extreme conditions encountered during fires. It employs a linearized Crank–Nicolson scheme for the conservation equations of energy and mass and its performance is evaluated against dynamic soil temperature and moisture observations, which were obtained during laboratory experiments on soil samples exposed to surface heat fluxes ranging between 10 000 and 50 000 W m−2. The Hertz–Knudsen equation is the basis for constructing the model's non-equilibrium evaporative source term. Some unusual aspects of the model that were found to be extremely important to the model's performance include (1) a dynamic (temperature and moisture potential dependent) condensation coefficient associated with the evaporative source term, (2) an infrared radiation component to the soil's thermal conductivity, and (3) a dynamic residual soil moisture. This last term, which is parameterized as a function of temperature and soil water potential, is incorporated into the water retention curve and hydraulic conductivity functions in order to improve the model's ability to capture the evaporative dynamics of the strongly bound soil moisture, which requires temperatures well beyond 150 °C to fully evaporate. The model also includes film flow, although this phenomenon did not contribute much to the model's overall performance. In general, the model simulates the laboratory-observed temperature dynamics quite well, but is less precise (but still good) at capturing the moisture dynamics. The model emulates the observed increase in soil moisture ahead of the drying front and the hiatus in the soil temperature rise during the strongly evaporative stage of drying. It also captures the observed rapid evaporation of soil moisture that occurs at relatively low temperatures (50–90 °C), and can provide quite accurate predictions of the total amount of soil moisture evaporated during the laboratory experiments. The model's solution for water vapor density (and vapor pressure), which can exceed 1 standard atmosphere, cannot be experimentally verified, but they are supported by results from (earlier and very different) models developed for somewhat different purposes and for different porous media. Overall, this non-equilibrium model provides a much more physically realistic simulation over a previous equilibrium model developed for the same purpose. Current model performance strongly suggests that it is now ready for testing under field conditions.

Identification of agronomic traits to enhance biomass and grain yield of chickpea under rainfed short-duration environment

Low biomass yield is considered to be a major limiting factor of chickpea productivity in semi-arid short duration environments of Peninsular India. Correlation and path coefficient analyses performed on grain yield and 14 other agronomic traits of 25 diverse chickpea genotypes to assess direct and indirect contribution of each trait to grain yield and formulate an effective selection criteria to improve biomass and grain yield of chickpea under residual soil moisture condition. Results have shown that biomass had the largest positive direct effect on grain yield and selection of tall types with more number of secondary branches/plant and seeds/plant and seeds of large size would be highly rewarding in simultaneously increasing biomass and grain yield of chickpea. JG 11, BGD 103, BGD 121 and BGD 72 are some of the high biomass and grain yield producing genotypes adapted to rainfed conditions of short duration environments.

Study on Effect of Supplementary Irrigation on Rainfed Chickpea (Cicer arietinum L.)

Chickpea is one of the important winter legumes in Nepal. It is grown after rice or maize either as sole or mixed crop. In Nepal, chickpea is mostly grown as rainfed crop on residual soil moisture or sometimes under irrigation. Lack of irrigation results drought and heat stress which affects crop growth and development. Irrigation at proper time is one of the most important factors for achieving higher crop yield. The experiment regarding use of supplementary irrigation time on chickpea was carried out at Regional Agricultural Research Station, Khajura, Banke, Nepal during the winter season of the year 2011 and 2012. The experiment was laid out in Randomized Complete Block Design with three replications. Seven different time intervals of irrigation was applied in the experiment for both years. Treatments differed significantly in terms of grain yield but showed non -significant difference in days to flowering and maturity over the years. The combined analysis of the experiments showed that the highest grain yield (2318 kg/ha) was produced when irrigation was supplied at vegetative stage followed by irrigation supplied at flowering stage (2298 kg/ha) and pod fill stage (2104 kg/ha) respectively.Int J Appl Sci Biotechnol, Vol 3(3): 431-433

Assessing Genetic Variability for Root Traits and Identification of Trait‐Specific Germplasm in Chickpea Reference Set

ABSTRACTChickpea (Cicer arietinum L.) is a major grain legume cultivated largely on residual soil moisture in the arid and semiarid regions of the world. Terminal drought stress is one of the major causes of yield loss, and a deep root system has been recognized as one of the most important traits for enhancing drought adaptability. To diversify the current genetic base of root traits, the present study explored the variation for root traits in the reference set of chickpea (n = 300) germplasm. Genetic variability for root traits at 35 d after sowing was assessed using a polyvinyl chloride (PVC) cylinder culture system in two postrainy seasons. Largest genetic variability was observed for dry weights of shoot (broad‐sense heritability [h2] = 0.69–0.74) and root (h2 = 0.52–0.70). For root‐length density (h2 = 0.42–0.43) and root/total‐plant dry‐weight ratio (h2 = 0.32–0.54), h2 values were moderate but the variation was large, indicating scope for selection. The performance of the reference set accessions was identified for each of key traits. Accessions with the best root‐length densities along with root and shoot dry weights were found to originate from the Mediterranean region and western Asia emphasizing the importance of whole collection from these regions for superior root traits. This study identified 23 new accessions for widening the parental base in further drought tolerance breeding efforts and identified superior traits in already adapted genetic backgrounds.

Performance of sweet gourd as relay with transplanted aman rice under rainfed ecosystem in Sylhet region

This study was carried out to evaluate the economic benefits of sweet gourd relay with transplanted aman rice under farmer’s field condition at Farming System Research and Development (FSRD) site, Jalalpur and Multi Location Testing (MLT) site, Zakigonj of Sylhet region during 2012-2013 and 2013-2014. The treatment combinations T1: T. aman rice / sweet gourd (var. Mollika), T2: T. aman rice / sweet gourd (var. Hatirpara) local, T3: Sweet gourd (var. Mollika) sole, T4: Sweet gourd (var. Hatirpara) sole and T5: T. aman rice sole (var. Binadhan-7) was maintained. The study was based in a randomized complete block (RCB) design with six dispersed replications. Results in terms of the crops yield, rice equivalent yield, gross return and net return with benefit cost ratio showed higher in sweet gourd / transplanted aman rice relay cropping system. So, sweet gourd relayed with transplanted aman rice could be an economically viable technology, instead of sole cropping, for best utilization of fallow land with residual soil moisture in Sylhet region.Bangladesh Agron. J. 2014, 17(2): 47-53

Field Observations of Regional Controls of Soil Hydraulic Properties on Soil Moisture Spatial Variability in Different Climate Zones

Knowledge of soil moisture spatial variability (SMSP) is important for many practical reasons. However, a significant gap still exists in our understanding of different controls on SMSP, especially the roles of soil hydraulic parameters due to their limited availability. Although modeling approaches have been used to assess the impacts of those parameters on SMSP, they have led to inconsistent findings. In this study, soil moisture data from Utah (5 yr) and the US Southeast (2 yr) were obtained from the Soil Climate Analysis Network (SCAN), along with estimated van Genuchten parameters. The method of mean relative difference (MRD) of soil moisture was used as a diagnostic tool for assessing different climate and soil controls on SMSP. The results show that instead of being controlled by climate variables (e.g., precipitation and potential evapotranspiration) as traditionally believed at regional scales (∼105 km2), MRD is mainly dependent on soil hydraulic properties. In Utah with a drier climate, the residual soil moisture content (θr) is the dominant control on MRD, followed by the saturated soil moisture content (θs). With wetter climates in the US Southeast, the impacts of θr and θs on MRD become comparable, mostly due to the high correlation between θr and θs in this region, and there exists a nonlinear negative relationship between MRD and the parameter n for coarser soils, indicated by larger n values tending to have lower MRDs. The findings of this study have important implications for verifying remotely sensed moisture data and initializing and parameterizing regional land surface and climate models.

A drought index designed for field-scale water management

A drought index with respect to the spatio-temporal scale was developed in response to the demand from the agricultural sector in South Korea. The new drought index was calculated based on the soil water balance between the supply and demand of water. The water supply was estimated using the cumulative effective precipitation weighted by the precipitation from two months prior. The water demand was derived from the actual evapotranspiration, which was calculated by applying a crop coefficient to the reference evapotranspiration. The amount of surface runoff on a given soil type was used to calculate the residual soil moisture. The presence of drought was determined based on the probability distribution in the given area. In order to assess the reliability of this index, termed the Agricultural Drought Index (ADI), the amount of residual moisture, which represents the severity of a drought, was compared to the measurements of soil moisture at three experimental sites between July 2012 and December 2013. The results showed that the ADI had greater correlation with measured soil moisture than did the Standardized Precipitation Index (SPI), suggesting that the ADI is a useful indicator of drought. While both the SPI and ADI showed similar trends in the temporal variation of drought conditions at all of the sites, the ADI better detected ‘severe drought’ than did the SPI. The daily relief of severe drought due to precipitation was also better represented by the ADI. Using the high-resolution climatic and spatial data of a small watershed, we produced 270m resolution maps of ADI from week 36 through week 41 of 2013, demonstrating the feasibility of the ADI as an operational drought monitor appropriate for the agricultural environment of South Korea.

Characterization and crop planning of rabi fallows using remote sensing and GIS.

Rice is the principal crop during kharif (rainy) season in eastern India, which occupies 26.8 M ha accounting for 63.3% of the total rice-growing areas of the country. However, this area is not fully utilized for crop production in the subsequent rabi (post-rainy) season and kept fallow due to a number of biotic, abiotic and socio-economic constraints. If this rabi fallow area can be effectively utilized, it will help in improving the economy of this region, which is yet to be benefited from the green revolution. The objectives of the present study include: (i) delineation of rabi fallow areas of eastern India using remote sensing and GIS technique; (ii) characterization of soil resources of the rabi fallow regions, and (iii) suggesting site-specific crop planning for this region. It was estimated that about 12.54 M ha area in the rabi season is left fallow in eastern India. The soil properties like soil texture, soil moisture retention at field capacity and permanent wilting point, saturated hydraulic conductivity, soil pH, electrical conductivity, soil organic carbon, etc. were determined at the representative profiles distributed in different agro-ecological sub-regions (AESRs) of this region and mapped in a GIS environment. Using water balance studies, site-specific crop planning based on available residual soil moisture has been suggested. In most of the AESRs, pulses and oilseeds like green gram, black gram, Sesamum and mustard can be grown successfully on residual soil moisture content. Crops which suffer from water deficit during maturity stages can also be grown during rabi season with one or two supplemental irrigations, wherever possible. If the site-specific constraints to crop production can be alleviated and these fallow lands can be brought under cultivation through proper crop planning as suggested, poverty in this resourceful region can be eradicated to a great extent.

Analysis of Resource-Use Efficiency and Productivity of Residual Soil Moisture Tomato Production in Kaduna State, Nigeria

This study was conducted to examine the resource-use efficiency and productivity of residual soil moisture tomato production Kaduna state, Nigeria. Descriptive statistics and production function analysis were used to analyze the data. The result showed that the production function analysis showed that 54.55% of the residual soil moisture tomato yields among the sampled farmers were explained by the specified inputs. The coefficients of land and labour, and Seed/seedlings significantly influence the output of residual soil moisture of tomato production. Similarly, land and seed were under-utilized, while labour is the most was over used. To improve the efficiency of inputs used, the study recommends that farmer’s access to modern technologies should be enhance, there should be effective and efficient extension service, easy access to formal credit facilities and also encourage them to form cooperative societies to enable them procure their inputs at reduce rate.