Average Crop Evapotranspiration Research Articles

ENERGY ASPECTS OF CONILON COFFEE DEVELOPMENT IN NORTHERN FLUMINENSE. PART 2 - ENERGY BALANCE

Conilon coffee represents a large portion of Brazilian coffee production, and it is essential to understand how the crop relates to the energy available in the environment. Therefore, this study sought to determine the components of the energy balance of the Conilon coffee crop in the North Fluminense region during seven harvests. The experiment was conducted in a crop field in the area belonging to the Darcy Ribeiro State University of North Fluminense, in Campos dos Goytacazes, RJ, which contains a micrometeorological station that monitored environmental data between June 2015 and May 2022. Using this information, the energy balance was performed using the Bowen ratio method, which made it possible to determine the crop evapotranspiration (ETc), the reference evapotranspiration (ET0), and the crop coefficient (Kc). The Bowen ratio energy balance method performed satisfactorily and indicated that 66% of Rn was converted to LE, 24% to H and 10% to G. The average crop evapotranspiration was 3.81 mm.day-1 and the average Kc per harvest showed an increasing trend throughout the experiment and ranged from 0.82 to 0.92. Conilon coffee presented an average productivity of 3.43 t.ha-1 (57.16 sc.ha-1) and it was concluded that an average of 0.08 g per MJ of net energy was produced.

Spatial estimation of water requirement in greengram under changing climates of North Interior Karnataka

Greengram is one of the major protein rich grain legumes predominately cultivated in North Interior Karnataka (NIK). The study aimed at determining the water requirement of greengram variety DGGV- 2 using CROPWAT model that helps the farmers of NIK consisting of 12 districts in tapping the potential yields of this crop through proper irrigation management. The decadal analysis for 60 years was done under past (1991-2020) and projected climate (2021-2050) as per the recommended practices of UAS, Dharwad across four dates of sowing from 07th June to 28th June at weekly interval. The average crop evapotranspiration (ETc), effective rainfall (ER) and irrigation requirement (IR) under past climates (1991-2020) for NIK were 246, 269.3 and 37.4 mm, respectively. An increase of 26.8 mm in ETc, 21.6 mm in ER and decrease of 0.3 mm in IR were simulated under projected climates. Sowing late i.e., on 28th June under projected climate (2021-2050) simulated the lowest water requirement and irrigation requirement for all the 12 districts of NIK. The spatial distribution of ETc, ER and IR for all the 12 districts of NIK were interpreted under both past and projected climates using ArcGIS software.

Effect of Changing Climate on Water Requirement of Chickpea in North Interior Karnataka: Cropwat Model based Assessment

Background: Chickpea is one of the major protein rich legume crops predominantly cultivated in North Interior Karnataka (NIK). The study aimed to determine water requirement of chickpea (variety BGD- 103) using CROPWAT model that helps in tapping the potential yields of the crop through proper irrigation management by the farmers of North Interior Karnataka (NIK), which consists of 12 districts with 88,361 km2 area. Methods: The crop was simulated by considering recommended practices of UAS, Dharwad across four dates of sowing from 01st October to 15th November at quarterly interval for the past (1991-2020) and projected period (2021-2050), and the decadal analysis was done for the past and projected climate. The analysed climate, crop and soil data were used for simulation using CROPWAT model. Results: The average crop evapotranspiration (ETc), effective rainfall (ER) and irrigation requirement (IR) under past climate (1991-2020) for NIK were 292.6, 57.4 and 245.9 mm, respectively. Decrease of 67 mm in ETc, 91.3 mm in IR and an increase of 40.8 mm in ER were observed under projected climate. Sowing early i.e., on 01st October under projected climate (2021-2050) simulated the lowest water requirement and irrigation requirement for all the 12 districts of NIK.

Continuous maize cultivation with high nitrogen fertilizers associated with the formation of dried soil layers in the semiarid farmland on the Loess Plateau

• Different land use types were chosen to determine soil desiccation. • Long-term maize cultivation with high yield caused a DSLs in the deep soil layers. • Crop rotations are recommended for maize production in the semiarid environment. Sustainable agriculture ensures food security and combats climate change by minimizing reliance on water resources. Maize ( Zea mays L.) is commonly grown with plastic mulching practice on the Loess Plateau of China, but its impact on soil desiccation is not well understood. We compared the effects of different land-use, including 17-year continuous wheat cultivation, 19-year pea-wheat rotations, 12-year continuous maize cultivation (high yield), 30-year multi-crop rotations, and 9-year continuous maize cultivation (varying yield) under four nitrogen (N) fertilization rates (i.e., 0, 100, 200, and 300 kg N ha −1 ). Average crop evapotranspiration during 2009–2020 for long-term continuous wheat, pea-wheat rotation, high-yielding maize, and multi-crop rotations was 222, 201, 277, and 393 mm, respectively, while average effective precipitation from March to September was 329 mm for all treatments. Continuous high-yielding maize cultivation formed a dry soil layer (DSL) in the deep soil profile (>400 cm), which was not found in other cultivation modes. After 9-year continuous high-yielding maize cultivation, 300 kg N ha −1 applying (20.9 Mg ha −1 biomass yield) formed the DSLs in the 360–960 cm soil profiles, while under 200 kg N ha −1 (20.1 Mg ha −1 biomass yield), the soil water content was almost close to the threshold of DSL in the 600–740 cm soil depth; while under 0 and 100 kg N ha −1 (<15 Mg ha −1 biomass yield), the DSL was not found along the soil profile, indicating that DSL formation under continuous maize cultivation was is driven by high N rates (or high yield level). These results suggest that long-term high-yielding maize cultivation with plastic mulching causes severe soil water depletion, resulting in the formation of a DSL in the deep soil profile. To maintain productivity, farmers should not be encouraged to carry out long-term continuous cropping of high-yielding maize in the semiarid environment on the Loess Plateau.

Model Validation, Crop Coefficients and Yield Response Factors for Maize Irrigation Scheduling based on Long-term Experiments

This paper reports on using independent historic datasets relative to 19 years (1972–1990) experiments with maize for the calibration, validation and further testing of the irrigation scheduling simulation model ISAREG, and to derive appropriate crop parameters. The experiments concern diverse irrigation and rainfed treatments in a Vertisol at Pustren experimental site (Stara Zagora). The calibration of the model consists of deriving crop coefficients Kc and depletion fractions for no stress relative to the main crop growth stages, thus adapted to local climate and soil conditions, through searching the minimal differences between observed and model-simulated soil water content. The calibration was performed using data for 1976, while data for 1987 was used for validation. The resulting average errors of the estimate (AEE) for the soil water content are respectively 0·012 and 0·023 cm3 cm−3, thus indicating appropriate model parameterisation. The accuracy of the calibrated model was tested against experimental long-term data (1972–1990) from all irrigation and rainfed treatments by comparing the computed versus observed seasonal evapotranspiration. Results show a regression slope b close to the 1:1 line and a relatively small value for AEE, 49·75 mm season−1, which is less than 10% of the average crop evapotranspiration observed. The yield response factor Ky was also derived from the observed data sets for the two hybrid varieties used, resulting in a value for Ky of 1·0 for the hybrid Kn606 adopted during the first decade and a value of 1·5 for the hybrid H708 used during the second one. A statistical test was also performed to compare the model predicted versus observed relative yield decrease due to water stress for both varieties yielding a regression slope b of 0·952 and an error AEE of 0·048 for the hybrid Kn606 and b of 0·958 and AEE of 0·067 for the H708, which show that model predictions are appropriate. The results obtained support model use for developing water saving and environmentally oriented irrigation practices in the Trace region, South Bulgaria.

Evapotranspiration and seed yield of field grown soybean under deficit irrigation conditions

Evapotranspiration was measured for a reference crop, rye grass ( Lolium prerenne) and soybean ( Glycine max L. Merril) grown over two seasons in 2000 and 2001 at Tal Amara Research Station, Lebanon, using drainage and weighing lysimeters. Climatic data from the field weather station were recorded daily. Within the experimental plots, irrigation was withheld at full bloom, R2 stage (S1 treatment), at seed enlargement, R5 stage (S2 treatment) and at mature seeds, R7 stage (S3 treatment). Further, a control (C) was fully-irrigated throughout the growing period. Average crop evapotranspiration (ETc) as measured by the drainage lysimeters in 2000 totaled 800 mm for a total growing period of 140 days. However, when ETc was measured by the weighing lysimeter in 2001, it was 725 mm during a growing period of 138 days. Average crop coefficients ( K c) were computed for different growth stages for the two growing periods by dividing the measured crop evapotranspiration (ETc) by the corresponding measured reference evapotranspiration (ETo-rye grass). K c values ranged from 0.62 at V10 stage (10th node on the main stem beginning with the unifoliolate node) to 1.0 at pod initiation, then to 0.81 at mature pods. Growth parameters, leaf area index (LAI) and dry matter accumulation, have been shown to be sensitive to water stress caused by the deficit irrigations. However, growth parameters were found to compensate for water stress at early stages, while at seed maturity the compensation ability was decreased. Plants of the lysimeters produced average aboveground biomass and seed yield of 8.1 and 3.5 t ha −1, respectively. However, in the well-irrigated field treatment, aboveground biomass and seed yield averaged 7.3 and 3.2 t ha −1, respectively. Deficit irrigation at R2 stage reduced aboveground biomass and seed yield by 16 and 4%, respectively, while deficit irrigation at R5 stage reduced these two parameters by 6 and 28%, respectively, with comparison to the control. The significant decrease in biomass at R2 stage due to water deficit may be attributed to a pronounced reduction in the number of vegetative nodes. However, limited irrigation at this stage did not reduce significantly ( P < 0.01) neither seed number nor seed weight, while at R5 stage these two parameters were reduced by 20 and 10%, respectively, with comparison to the control. Results showed also that deficit irrigation at R7 stage (S3) was more profitable than irrigation deficit at any other crop phenology and did not cause significant reductions either in seed number or seed weight.