FAO Method Research Articles

Growth, Evapotranspiration, Gas Exchange and Chl a Fluorescence of Ipê-Rosa Seedlings at Different Levels of Water Replacement.

In general, young plants in the establishment phase demonstrate sensitivity to changes in environmental conditions, especially regarding water availability. The effects of the seasonality of biophysical processes on plant physiology can trigger differential responses, even within the same region, making it necessary to conduct studies that characterize the physiological performance of the species at different spatial and temporal scales, making it possible to understand their needs and growth limits under water stress conditions. This paper aimed to evaluate the growth, gas exchange and Chl a fluorescence in ipê-rosa seedlings subjected to levels of water replacement (LWRs) of 100, 75, 50 and 25% in a greenhouse. The morphometric variables of plant height, diameter at stem height, numbers of leaves and leaflets, root length and volume, plant dry mass and leaf area were evaluated. The potential evapotranspiration of seedlings (ETc) was obtained using direct weighing, considering the water replacement of 100% of the mass variation between subsequent days as a reference; the cultivation coefficients (kc) were obtained using the ratio between ETc and the reference evapotranspiration (ETo) obtained by the Penman-Monteith FAO-56 method. Biomass and evapotranspiration data were combined to determine water sensitivity. Diurnal fluxes of gas exchange (net photosynthesis rate, transpiration rate, stomatal conductance, internal and atmospheric carbon ratio, water use efficiency and leaf temperature) and Chl a fluorescence (Fv/Fm, ΦPSII, ETR, Fv'/Fm', NPQ and qL) were evaluated. Water restriction caused reductions of 90.9 and 84.7% in the increase in height and diameter of seedlings subjected to 25% water replacement when compared to seedlings with 100% water replacement. In comparison, biomass accumulation was reduced by 96.9%. The kc values increased throughout the seedling production cycle, ranging from 0.59 to 2.86. Maximum water sensitivity occurred at 50% water replacement, with Ky = 1.62. Maximum carbon assimilation rates occurred in the morning, ranging from 6.11 to 12.50 µmol m-2 s-1. Ipê-rosa seedlings regulate the physiology of growth, gas exchange and Chl a fluorescence depending on the amount of water available, and only 25% of the water replacement in the substrate allows the seedlings to survive.

Comparison between evapotranspiration estimate methods in the state of Rio Grande do Sul

The characterization of evapotranspiration requires time and financial investment, but from meteorological data, it is possible to estimate the values of this phenomenon by means of indirect methods. The Penman-Monteith FAO (PM) method is considered the most accurate by the Food and Agriculture Organization of the United Nations (FAO), which recommends its use because it takes into account solar radiation, temperature, relative humidity, and wind speed, data that are not always available in some locations in Brazil, making it necessary to use more simplified methods. Therefore, the objective of this work is to compare the evapotranspiration estimated by the Penman-Monteith FAO method with the evapotranspiration estimated by the methods of Penman-Monteith Simplified (PMS), Priestley-Taylor (PT), and Hargraves-Samani (HS) for the 10 weather stations of the National Institute of Meteorology (INMET) distributed in the Pampa biome in the state of Rio Grande do Sul. The results obtained indicated some divergences between the compared methods. However, the PT method showed more accurate results, with the best performance among the proposed methods. This indicates that this method can be used in future studies in the region, especially in cases of a lack of meteorological data.

Step by Step Calculation of the Penman-Monteith Evapotranspiration (FAO-56 Method)

AE459, a 12-page fact sheet by Lincoln Zotarelli, Michael D. Dukes, Consuelo C. Romero, Kati W. Migliaccio, and Kelly T. Morgan, provides a step-by-step calculation of the reference evapotranspiration (FAO-56 method) for a given location from the available weather data. Includes references. Published by the UF Department of Agricultural and Biological Engineering, February 2010.

EVALUASI KESESUAIAN LAHAN TANAMAN JAGUNG (Zea Mays L) DI KECAMATAN MALUA KABUPATEN ENREKANG

This study aims to determine the actual and potential land suitability of maize crops and its limiting factors in Malua District. The method used in this research is survey method and descriptive data analysis and determination of land suitability class based on FAO method. The results showed that the actual land suitability of maize crops in Malua District, Enrekang Regency, land units 1,2,3,4,5,6,7,8,9,10,11 and 12 are marginally suitable (S3) with nutrient availability factor (P2O5). While the potential land suitability is quite suitable (S2) with the limiting actor of rooting media (soil texture).

EVALUASI KESESUIAN LAHAN TANAMAN BAWANG PUTIH (Allium stivum L.) DI KECAMATAN MONCONGLOE KABUPATEN MAROS

The study aims to determine the actual and potential land suitability and limiting factors of garlic in Moncongloe District, Maros Regency. The research was conducted from August to October 2021 in Moncongloe District, Maros Regency, and Soil Science Laboratory, Faculty of Agriculture, Universitas Muslim Indonesia Makassar. The method used in the research was survey method and descriptive data analysis and determination of land suitability class based on FAO method modified by the Ministry of Agriculture. The results showed that the actual land suitability of garlic is not suitable (Nwa.eh) for land units 6, 7, 8, and 9, as well as not suitable (Nwa) for land units 1, 2, 3, 5, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, and 22. While the potential land suitability is quite suitable (S2tc.wa) for all land units in Moncongloe District, Maros Regency. The inhibiting factors are average temperature (tc) and water availability (rainfall).

Estimating crop coefficients and water use of a full-bearing mango orchard in north-eastern South Africa using the fraction of vegetation cover and a dual source evapotranspiration model

In semi-arid countries like South Africa, commercially produced mango (Mangifera Indica L.) are grown entirely under irrigation. However, there is little accurate quantitative information on the water use of mango orchards, and few accurate water use models currently exist. In this study, we evaluated the performance of the FAO 56 method of estimating crop evapotranspiration (ETc) and a dual source water use model against measurements of actual consumptive water use of a commercial mango orchard. The FAO approach calculates ETc as the product of a crop coefficient (Kc) and the reference evapotranspiration (ETo). We derived Kc for well-watered orchards from readily available data including the fraction of vegetation cover, average tree height, and a stomatal control coefficient. The dual-source model calculated orchard evapotranspiration as the sum of tree transpiration and orchard floor evaporation derived from the modified Shuttleworth and Wallace model. Actual evapotranspiration was measured using an open path eddy covariance system, while tree transpiration was measured using the heat ratio method of monitoring sap flow. Data were collected in a mature ‘Tommy Atkins’ mango orchard grown with micro-sprinkler irrigation in north-eastern South Africa. Results show that the reference evapotranspiration explained most of the variation in orchard transpiration (R2 ∼ 0.78) compared to the solar radiation (R2 ∼ 0.66) and the vapour pressure deficit of the air (R2 ∼ 0.66). Compared with field measured water use data, the FAO method gave relatively accurate estimates of transpiration (R2 = 0.74, NRMSE = ±18.00 %, NMAE = ±15.00 %, NSE = 0.70) and evapotranspiration (R2 = 0.58, NRMSE = ±19.00 %, NMAE = ±16.00 %, NSE = 0.55). NSE is the Nash-Sutcliffe Efficiency. The dual-source model yielded slightly less accurate estimates of transpiration (R2 = 0.61, NRMSE = ±22.00 %, NMAE = ±20.00 %, NSE = 0.39) and evapotranspiration (R2 = 0.52, NRMSE = ±23.00 %, NMAE = ±25.00 %, NSE = 0.51). The basal crop coefficient (Kcb) showed small seasonal fluctuations, varying between 0.40 and 0.60 throughout the year. In contrast, Kc showed clear seasonality varying between 0.59–0.64 at flowering and fruit set and rising to 0.81–0.90 during the fruit growing phase. Estimates of the annual total transpiration (686 mm) from the FAO method were within 5 % of the actual measured values (677 mm) while the dual source model estimated 612 mm of transpiration, which was almost 10 % lower than the measured values. The results highlight that even though the FAO method requires fewer input parameters, it is potentially more accurate in estimating water use in mango orchards than the dual-source model.

Estimation of water consumption volume and water efficiency in irrigated and rainfed agriculture based on the WaPOR database in Iran

ABSTRACT To evaluate the WaPOR model across the entire country of Iran, initially, 16 provinces located in four different climatic regions were selected for calculating and comparing the evapotranspiration using both the FAO-56 method and the WaPOR approach. The comparison of 10-day evapotranspiration values obtained from the FAO56 method and WaPOR demonstrates that the WaPOR model exhibits the highest correlation with FAO-56 values in semi-arid regions, with an R2 = 0.95 and an RMSE = 0.43. The analysis of evapotranspiration variations indicates that the evapotranspiration in the Caspian Sea and Zagros foothill regions has experienced more significant changes from 2015 to 2022. The annual analysis of net blue water productivity demonstrates that the net productivity in rainfed lands strongly depends on the precipitation received. Also, considering the importance of investigating the accuracy of biomass estimation, the correlation between the accuracy of biomass estimation and actual evapotranspiration was examined in four Iran climatic regions. Using the WaPOR model provides acceptable results for water consumption management and assessment in different regions and climates of Iran, particularly in agricultural lands. The WaPOR model can serve as a guide for determining reliable values of evapotranspiration and planning related to water resources in the agricultural sector in Iran.

High-resolution satellite imagery to assess orchard characteristics impacting water use

Most Orchards throughout the Mediterranean basin rely heavily on irrigation, a dependency increasing due to climate changes. Assessing the water requirement (WR) is crucial and depends on different factors, including orchard age, tree density per field, inter-row management. This study proposes new methods to evaluate these characteristics with remote sensing (RS). Various remote sensors providing high and very high spatial resolution images are investigated and their accuracy is assessed. The final objective is to assess WR using variables derived from remote sensing compared to data provided by water managers and from the FAO method. A typical Mediterranean watershed was selected in South-Eastern France, with orchards having various agricultural practices. Original methods were developed with Sentinel 2 (S2) data (2016–2023), 1 Pleiades image (2022) and the extraction of Google-satellite-hybrid images (GSH, 2017), and assessed using a large ground observation dataset (information on water use collected on 366 fields). Five orchards were monitored by capacitive sensors to assess the water balance. Irrigation durations ranged from 3–300 hours/year, with decision influenced by tree density and plot age. To identify young orchards, a thresholding approach on S2 derived NDVI effectively identified young orchards achieving a 98% accuracy rate. Grassed and non-grassed orchards were mapped using two methods, with a random forest classification using three spectral bands with 72% accuracy and a supervised approach yielding 81% accuracy for GSH and 57% for Pleiades. The performance depends on the acquisition date of images. A pattern detection algorithm applied to GSH and Pleaides determined tree density, showing a high correlation (r²=0.9) with observed data. These RS derived variables allowed to compute orchard water requirements at the watershed scale, ranging from 70 to 550 mm annually depending on management practices. The proposed methods can be extrapolated to other territories and are implemented using open access softwares.

Determination of Evapotranspiration and Crop Coefficients of Irrigated Legumes on Different Soil Textures Using the FAO56 Approach

Climates and locations specific crop coefficients (Kc) plays pivotal roles in effective water management and crop yield optimization. Research on Kc for many staple crops remains limited in many regions across Africa. This study examined the crop coefficients of two varieties of cowpea (Sampea 14 and Sampea 17) and a variety of soybean (TGX 1465-1D) across different soil textures for optimized water management and crop yield. This study ascertained the Kc of Sampea14 (V1), Sampea17 (V2), and TGX 1465-1D (V3) cultivated on sandy, sandy clay loam, and sandy loam soils, within Port Harcourt, Southern Nigeria. This formed a 3 by 3 factorial experiment in three replicates. Changes in soil water content and crops’ agronomic parameters were monitored regularly. Meteorological data were obtained from the National Aeronautic and Space Administration website and reference evapotranspiration were estimated from the meteorological data using the FAO Penman Monteith’s method. Kc were estimated from the actual crop water use and reference crop evapotranspiration using the FAO56 method. During the initial-growth stage, the average Kc for V1, V2, and V3 were computed as 0.55, 0.72, and 0.81, respectively. At the mid-growth stage, these coefficients increased to 1.48, 1.30, and 1.60 and at the late season, the average Kc were 0.80, 0.69, and 0.86, for the respective varieties. The findings from this study hold the potential to significantly contribute to proper water management practices in the studied area. The understanding of Kc for these specific legume varieties across different soil textures offers valuable insights for optimizing irrigation scheduling and ultimately enhancing crop yield and water productivity.

Evaluation of soil quality and land suitability in different management systems

ABSTRACT This study aimed to evaluate the effect of management systems on soil quality in rangeland and agricultural lands (smallholder, total owner, and Binaloud Company) in Neyshabur plain, northeastern Iran. Twenty-one soil profiles were described and sampled. The weighted and additive soil quality indices (SQI) of surface soil and soil profile (0–100 cm) were calculated. The minimum data set (MDS) was determined using principal component analysis (PCA) and expert opinion (EO) methods. The land index (LI) for alfalfa was calculated using the FAO method. In all management systems, the EO-weighted SQI was the highest for surface soil and soil profile. The relationship between the EO-weighted SQI and alfalfa yield was the strongest in the total owner and Binaloud Company. The LI showed a better relationship with the alfalfa yield than the SQI. The SQI of soil profile provides more comprehensive information regarding the different soil management systems. The LI, which considers crop requirements, could be useful in comparing the soil quality for a specific plant. The lower soil quality in smallholder system is an early warning sign of soil degradation in the area. Furthermore, the SQI has sufficient capability to reveal the effects of the land exploitation systems on soil quality.

Spatial prediction of winter wheat yield gap: agro-climatic model and machine learning approaches.

This study aimed to identify the most influential soil and environmental factors for predicting wheat yield (WY) in a part of irrigated croplands in southwest Iran, using the FAO-Agro-Climate method and machine learning algorithms (MLAs). A total of 60 soil samples and wheat grain (1m × 1m) in 1200ha of Pasargad plain were collected and analyzed in the laboratory. Attainable WY was assessed using the FAO method for the area. Pearson correlation analysis was used to select the best set of soil properties for modeling. Topographic attributes and vegetation indices were used as proxies of landscape components and cover crop to map actual WY in the study area. Two well-known MLAs, random forest (RF) and artificial neural networks (ANNs), were utilized to prepare an actual continuous WY map. The k-fold method was used to determine the uncertainty of WY prediction and quantify the quality of prediction accuracy. Results showed that soil organic carbon (SOC) and total nitrogen (TN) had a positive and significant correlation with WY. The SOC, TN, normalized different vegetation index (NDVI), and channel network base level (CHN) were recognized as the most important predictors and justifying more than 50% of actual WY. The ANNs outperformed the RF algorithm with an R 2 of 0.75, RMSE of 400 (kg ha-1), and RPD of 2.79, according to statistical indices. The uncertainty analysis showed that the maximum uncertainty of the prediction map [400 (kg ha-1)] was very low compared to the mean value [4937 (kg ha-1)] of WY map. Calculation yield gap using the FAO-agro-climatic model showed that the average yield gap of the region was about 50% of actual yield. The findings of this study demonstrated that integrating simulated attainable crop growth using crop model and a set of soil and environmental covariates with the ANNs algorithm can effectively predict WY gaps in large areas with acceptable and reasonable accuracy. The study emphasizes that the implementation of efficient management practices has the potential to enhance agricultural production in the study area and similar regions. These results represent a significant advancement of sustainable agriculture and provide valuable insights for ensuring global food security.

Evaluation of the resistance of three maize varieties to Spodoptera frugiperda (J.E. Smith) and Ostrinia nubilalis Hübner in the Tonkpi region (Man, Côte d’Ivoire)

BackgroundThe corn borer Ostrinia nubilalis and the fall armyworm Spodoptera frugiperda larvae feed on the aerial parts of maize. It is responsible for significant yield losses and are therefore a cause of food insecurity. This study carried out to evaluate the resistance of three maize varieties (EV8766 SR-MRP, PR9131-SR, CEW-SR), in Tonkpi region’s, to S. frugiperda and O. nubilalis damages. Each maize variety seeds were sown on a one hectare plot subdivided into 6 elementary plots with 75 cm between rows and 40 cm between bunches. Sampling of S. frugiperda and O. nubilalis larvae on maize plants was carried out according to the FAO method, from the third to the fifth week after planting. Maize plants damaged, the intensity of infestation and the number of larvae on maize plants were recorded. Maize plants damaged by the insect pests were marked to avoid recounting. At maturity, 100 maize cobs were harvested per elementary plot, then the larvae number and the attacked cobs by S. frugiperda and O. nubilalis larvae were recorded.ResultsThe lowest damage rate by S. frugiperda were recorded in maize variety EV8766-SR-MRP (23.33%); while, the highest damage rate were in the varieties PR9131-SR (43.33%) and CEW-SR (55%). There are no significant difference values of the density of S. frugiperda larvae per maize plant attacked between the three varieties. The index of intensification of maize plant damaged by S. frugiperda larvae was lower for the variety EV8766-SR-MRP (7.50%) and was moderate for the varieties PR9131-SR (15.42%) and CEW-SR (21.67%). The damage rates of O. nubilalis larvae on maize cobs varied between 9.6 and 22.0%. These damage rates were higher for the varieties PR9131-SR (21.83%) and CEW-SR (17.50%) and were lower for EV8766-SR-MRP (9.66%). There was not significantly different from the density of O. nubilalis larvae per maize cob attacked between the three varieties. It was between 1 to 1.2 larvae. Crop losses were lower for EV8766 SR-MRP (10.228%) than those of PR9131-SR and CEW-SR (19.338%).ConclusionsThe maize variety EV8766-SR-MRP is found to be the best variety in the control of, O. nubilalis and S. frugiperda.

Calibrating the Ångström–Prescott Model with Solar Radiation Data Collected over Long and Short Periods of Time over the Tibetan Plateau

As the coefficients of the Ångström–Prescott model is site-dependent, the sparsity of radiation stations in regions like the Tibetan Plateau (TP) presents challenges for model calibration. Due to the unique climate and the clean air conditions over the TP, it might be feasible to calibrate the Ångström–Prescott model with short-term observations from scientific expeditions. To test this hypothesis, we used various datasets with different lengths at four stations, together with 435 daily radiations measured during a scientific expedition at Banga in the central TP from 2014 to 2015, to calibrate the Ångström–Prescott model. We found that calibration with a 1-year data length resulted in model performances comparable to those with a 20-year data length. Analysis of the expedition observations showed that the monthly average daily radiation ranged from 15.2 MJ/m2d in December 2014 to 26.5 MJ/m2d in July 2015, with an average value of 20.6 MJ/m2d. When this set of expedition data was used for calibration, the Ångström–Prescott model performed well with an NSE (Nash–Sutcliffe efficiency) of 0.820. If no data were available for calibration, the coefficients of the Ångström–Prescott model could also be directly calculated by parameterization methods established with calibrations at the other radiation stations. In this situation, the LiuJD method performed the best with the highest NSE of 0.792, followed by the LiuXY method with an NSE of 0.764. The FAO method performed poorly with an NSE of 0.578, while the Gopinathan method performed the worst with the lowest NSE of 0.218. Thus, the best strategy to calibrate the Ångström–Prescott model in the Tibetan Plateau is to use data from local observations, even if collected over short periods. When these are not available, the coefficients of the Ångström–Prescott model should be calculated using the parameterization method established with calibrations over the Tibetan Plateau.

Missing Rainfall Daily Data: A Comparison Among Gap-Filling Approaches

AbstractMissing data is a frequent problem in meteorological and hydrological temporal observation data sets. Finding effective solutions to this problem is essential because complete time series are required to conduct reliable analyses. This study used daily rainfall data from 60 rain gauges spatially distributed within Portugal's Guadiana River basin over a 30-year reference period (1976–2005). Gap-filling approaches using kriging-based interpolation methods (i.e. ordinary kriging and simple cokriging) are presented and compared to a deterministic approach proposed by the Food and Agriculture Organization (FAO method). The suggested procedure consists of fitting monthly semi-variogram models using the average daily rainfall from all available meteorological stations for each month in a reference period. This approach makes it possible to use only 12 monthly semi-variograms instead of one for each day of the gap period. Ordinary kriging and simple cokriging are used to estimate the missing daily precipitation using the semi-variograms of the month of interest. The cokriging method is applied considering the elevation data as the secondary variable. One year of data were removed from some stations to assess the efficacy of the proposed approaches, and the missing precipitation data were estimated using the three procedures. The methods were validated through a cross-validation process and compared using different performance metrics. The results showed that the geostatistical methods outperformed the FAO method in daily estimation. In the investigated study area, cokriging did not significantly improve the estimates compared to ordinary kriging, which was deemed the best interpolation method for a large majority of the rainfall stations.

EVALUASI KESESUAIAN LAHAN PADI SAWAH (Oryza sativa L.) DI KABUPATEN LUWU

Rice is one of the food crops and commercial crops. Rice also has the potential to contribute significantly to increasing income and employment in rural areas. As indicated by rice imports from Thailand and Vietnam, national rice production has not been able to meet domestic demand. The objectives of this study were (1) to determine the actual and potential land suitability levels of rice plants in Luwu Regency and (2) to find out the limiting factors for actual and potential land suitability of rice plants in Luwu Regency. Evaluation of rice land suitability using the FAO method. Based on the limiting factors of land characteristics. The results showed that the actual land suitability of plants was marginal (S3fn) with the limiting factors for nutrient retention (organic C) and available nutrients (P2O5 and K2O). Efforts to improve the limiting factor can be made by adding 59.6 t organic matter ha-1, 332.6 kg P2O5 ha-1, and 98 kg K2O ha-1 so that the actual land suitability of marginal (S3) becomes very suitable (S1).

Assessment of the Midseason Crop Coefficient for the Evaluation of the Water Demand of Young, Grafted Hazelnut Trees in High-Density Orchards

Knowledge of crop water requirements is important in supporting irrigation management. Evapotranspiration (ET) is commonly measured with a variety of instruments and field procedures, but it is also typically computed or modeled using the FAO56 or FAO66 methods. The adoption of this approach requires the assessment of the crop coefficients. Some data are available for own-rooted hazelnut trees, but no data have been reported for young and grafted hazelnut trees. There is a need to update nut–tree crop coefficients, especially considering modern cultivars and production systems, such as those with a high tree density per ha−1. In this paper, the FAO66 crop transpiration coefficient Kc,Tr and the FAO56 dual crop coefficients Kcb were assessed for the mid-growing season of a young grafted hazelnut orchard. The field data were acquired manually and using UAV. The coefficients were determined for three tree densities and for two growing seasons. The crop coefficients, obtained using the FAO66 method, agreed with the literature data referring to low densities, while the FAO56 method could allow us to better define the crop coefficients for high-density hazelnut orchards.

Dietary Practices and Nutrient Intake of Internally Displaced School Children in the West Region of Cameroon.

Poor diets and subsequent malnutrition are among the greatest current societal challenges triggering immense health and economic burden especially among populations that are forcibly displaced. It is indispensable to establish the dietary patterns of any population, especially in displaced populations, in order to develop and effectively implement interventions for the specific population. A cross-sectional study was conducted to assess dietary practices and nutrient adequacy of 307 internally displaced pupils aged between 5 and 15 years in the West Region of Cameroon. Pretested, structured interviewer questionnaires were used to collect data on the demographic and socioeconomic status of the children and their caregivers, the nutrition knowledge of caregivers, the dietary practices of the children, dietary diversity, their food sources, and coping strategies that were used during food shortage. SPSS version 23 was used to analyze the data. The dietary diversity of the children was assessed at the individual level using FAO method of assessing women's dietary diversity score. Out of the total 307 children, 148 (48.2%) were boys and 159 (51.8%) were girls. During food shortages, most of the mothers/caregivers (72%) used borrowing as the main auxiliary food source and others (28%) used food as payment for work or begging. A majority of the children (56%) usually ate only two times in a day. Most of the children were of unacceptable or low dietary diversity (66.2%). The most frequently consumed food group was cereals as it was eaten by 21% of the children, seven or more times per week; meanwhile, the least was animal products with only 3% of the children consuming it seven or more times weekly. Their diets were energy-deficient (1640.5 ± 1.64 kcal) and unbalanced with daily inadequate protein (18.45 ± 1.13 g), vitamin A (470.27 ± 1.38 μg), and iron (4.02 ± 0.08 mg) intake. The nutrition knowledge of the mothers/caregivers was poor as less than half (41%) of them had an acceptable nutrition knowledge. The high prevalence of poor dietary patterns and poor nutrition knowledge imposes the necessity of developing nutritional interventions and education strategies aimed at promoting healthy eating habits in the children.

APPLICATION GIS IDENTIFY LAND AREA SUITABLE FOR RUBBER AND COFFEE TREES TO AGRICULTURE RESTRUCTURE GIA LAI PROVINCE

Gia Lai has great potential for developing agricultural production, and it is home to a large crop industrial material area in Vietnam. It boasts nearly 100,000 hectares of coffee and nearly 90,000 hectares of rubber. The area has immense potential to develop its agricultural production due to its unique characteristics of soil and climate, which can support a rich diversity of plants and animal with high economic value. By creating areas for intensive agricultural production and concentrating on commodity products with a competitive advantage, Gia Lai can improve the efficiency of its agricultural restructuring. To achieve this goal, this research has utilized the Land Evaluation Method of the FAO method and GIS to identify suitable land areas for rubber and coffee trees to restructure agriculture in Gia Lai province. the results indicate that the land suitability for coffee trees is mainly moderately suitable (S2) with 86,163 hectares of land suitable for cultivation. Coffee trees are primarily grown in districts such as Chu Pah, Dak Doa, Chu Se and Ia Grai. On the other hand, the land suitability for rubber trees is mainly moderately suitable (S2) with 60,000 hectares of land suitable for cultivation. Rubber trees are primarily grown in districts such as Chu Pah, Dak Doa, Chu Se, Ia Grai and Chu Prong. These areas are characterized by the distribution of red basaltic soils, rainfall exceeding 2500 mm, and a favorable climate for the development of industrial plants.

Understanding Drainage Dynamics and Irrigation Management in a Semi-Arid Mediterranean Basin

Irrigation is one of the main users of water worldwide and its overuse may affect the natural regimes of water systems. To avoid this, drainage and irrigation management needs to be improved. This study aims to determine the amount of water lost to drainage in a semi-arid Mediterranean irrigated area. Water use, rainfall and drainage were monitored for 12 months (2019–2020) in a 425 ha sub-basin in the Algerri-Balaguer irrigation district (8000 ha, NE Spain). In addition, irrigation requirements were estimated using the single-crop FAO-56 method and a two-source energy balance model (TSEB) was used to estimate actual evapotranspiration in the sub-basin. Water lost to drainage in the sub-basin was estimated as 18% of the total water that entered the perimeter as irrigation and rainfall, which are almost five time higher than theoretical requirements of leaching. Out of the total drainage water, 57% was estimated to be irrigation water and 43% rainwater. The average amount of irrigation water used was 614 mm and irrigation efficiency in the sub-basin was estimated at 80.2% and averaged actual evapotranspiration at 1144 mm. The available margin of improvement is between 19.3% of the present irrigation drainage ratio and the 3.8% estimated with the leaching requirement model.

Plant available water predicted by a flux-based approach

Plant available water (PAW) is an important indicator of soil suitability for crop growth and biomass production. Total available water (TAW) is defined as the difference between the water content at field capacity (FC) and at wilting point (WP). The readily available water (RAW) is a fraction of TAW defined as the water content between FC and the limiting point (LP). The challenge in determining TAW and RAW lies in the correct determination of FC, WP, and LP. We propose a process-based approach to address the issue, referenced as flux-based method (FBM). Five scenarios were used to assess the FBM: (1) generic soil-plant-atmosphere conditions, from which sensitivity analyses were performed; (2) a maize crop on several soils to compare the predictions of the FBM and the traditional FAO method; (3) mean plant-atmosphere conditions to map PAW from soil texture using the FBM and the FAO method; (4) a field experiment with a fully irrigated soybean crop; and (5) a field experiment with a common bean crop under water deficit. Resulting flux-based TAW and RAW showed high sensitivity to root length density and soil hydraulic parameters. The FBM tended to predict higher water contents at FC than the FAO method for maize crop scenarios. Texture triangles to predict TAW and RAW showed that the differences between the predictions of FBM and FAO are mostly due to the distinct values for FC, and for the LP, respectively. For both observed scenarios of soybean and common bean crops, the predictions of the FBM were plausible with time series of observed data. The FBM allows predicting PAW in Van Genuchten – Mualem type soils for different FC flux criteria, soil depths, root densities, and dynamic potential transpiration rates.