Search

The objective of this study was to evaluate the structural characteristics, yield and water use efficiency of forage cactus under daytime and nighttime irrigation in a Brazilian semiarid region. The experiment followed a completely randomized design in a 3 × 2 factorial scheme, with ten replications: three clones of forage cactus ("IPA Sertânia"—IPA, "Miúda"—MIU, "Orelha de Elefante Mexicana"—OEM) and two irrigation schedules (daytime and nighttime). Irrigation was applied once a week using a graduated cylinder. The structural characteristics (i.e., plant height and width, total number of cladode—TNC; cladode number per emergence order—CN1, CN2 and CN3; cladode area—CA; cladode area index—CAI), productive characteristics (fresh mass production per plant—FM and dry mass—DM) and water use efficiency (WUEFM and WUEDM) were obtained from the plant harvests. Our results showed that the irrigation schedules did not lead to significant differences in most of the response variables (p > 0.05), except for the TNC (13.2 und), CN2 (7.4 und) and CAI (1.58 m2 m−2) of MIU. It was observed that OEM presented the highest yield, WUEFM and WUEDM (p < 0.05). Adopting the OEM clone, regardless of the irrigation schedule, is the strategy that achieves the best production. [ABSTRACT FROM AUTHOR]

The proposal for a method of identifying the occurrence of desertification that has a strong association with in situ data leads to more assertive results when analysing the contribution of climate and social and economic factors to advancing the process. This study aimed to develop a methodology called the RisDes_Index to evaluate the evolution of the desertification process based on satellite data. The concept of the RisDes_Index method was based on the reflectance variables of the R, B and G bands, albedo and LAI of the Landsat 5/TM and Landsat 8/OLI satellites. Principal component analysis was used to assess the biophysical basis of the RisDes_Index by associating the results with micrometeorological data, physical and chemical properties, and vegetation cover data collected from five experimental sites in the semi-arid region of Brazil. These sites included one from a seasonally dry forest (i.e., the Caatinga), an agricultural cactus plantation, an area undergoing desertification, and two irrigated sugarcane crops (wetlands), one with and one without straw cover. The RisDes_Index was applied to all pixels of the images from 5 December 1991, 14 November 2001, 20 November 2009 and 6 October 2016 of an important desertification nucleus (DN) in the semi-arid region of Brazil, i.e., the DN of Cabrobó. The proposed RisDes_Index was able to identify areas with significant processes of desertification, which mainly occur in areas of sandy, acidic, bare soils with a high β value (Bowen ratio) and high soil temperature. The results of the RisDes_Index showed that in 5 December 1991, desertified areas comprised 38% of the total area of the DN of Cabrobó, expanding to 51% in 2016. Application of the RisDes_Index confirmed the advance of desertification in the DN of Cabrobó. This was due to a consequent increase in the water deficit and intensified deforestation to increase the areas of livestock farming. The RisDes_Index proved to be a robust method, as its estimation based on simple satellite products exhibited a strong association with biophysical variables of areas with different land uses and degradation levels. Thus, it is suggested that the RisDes_Index be applied in various regions of the world, with the idea of directing action to meet the advance of desertification. [ABSTRACT FROM AUTHOR]

The in-situ quantification of turbulent flux and evapotranspiration (ET) is necessary to monitor crop performance in stressful environments. Although cacti can withstand stressful conditions, plant responses and plant–environment interactions remain unclear. Hence, the objective of our study was to investigate the interannual and seasonal behaviour of components of the surface energy balance, environmental conditions, morphophysiological parameters, biomass yield and water relations in a crop of Nopalea cochenillifera in the semi-arid region of Brazil. The data were collected from a micrometeorological tower between 2015 and 2017. The results demonstrate that net radiation was significantly higher during the wet season. Latent heat flux was not significant between the wet season and dry season. During the dry-wet transition season in particular, sensible heat flux was higher than during the other seasons. We observed a large decline in soil heat flux during the wet season. There was no difference in ET during the wet or dry seasons; however, there was a 40% reduction during the dry-wet transition. The wet seasons and wet-dry transition showed the lowest Evaporative Stress Index. The plants showed high cladode water content and biomass during the evaluation period. In conclusion, these findings indicate high rates of growth, high biomass and a high cladode water content and explain the response of the cactus regarding energy partitioning and ET. [ABSTRACT FROM AUTHOR]

Copyright of Irrigation & Drainage is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Simulation models are useful tools for estimating plant response and contributing to the development of management strategies and yield predictions in crops. This study aimed to calibrate and evaluate the AquaCrop-FAO model for the forage cactus imposed on different cropping systems in the semi-arid region of Brazil. Four experiments were conducted: cactus-sorghum intercropping system with five spacings between plants (0.10, 0.20, 0.30, 0.40 and 0.50 m); cactus-sorghum intercropping system with five spacings between rows (1.00, 1.25, 1.50 and 1.75 m); single cactus with four levels of mulch (0, 5, 10 and 15 Mg ha−1); and single forage cactus with four levels of nitrogen fertilisation (50, 150, 300 and 450 kg of N ha−1). The performance of the model was evaluated using the following parameters: root mean squared error (RMSE); normalised RMSE (NRMSE), coefficients of determination (R2), Nash-Sutcliffe model efficiency coefficient (ME) and the Willmott index of agreement (d). During the calibration stage, the statistical indices pointed to the good performance of the AquaCrop model in estimating dry biomass in most of the cropping systems, with 10 < NRMSE <20; R2 > 0.96 and ME > 0.95. The AquaCrop model showed the best performance simulating systems under different levels of nitrogen fertilisation. Among the intercropping systems, the denser arrangements showed the highest values for simulated biomass. • With adjustments, the AquaCrop model can be used for forage cactus. • More dense crops have higher water productivity values. • Cactus-sorghum intercropping promotes increased crop productivity in relation to the single crops. [ABSTRACT FROM AUTHOR]

Analysing alternative methods for estimating reference evapotranspiration (ET0) is essential for improving the management of water resources, especially where meteorological data are not fully available for application of the standard Penman–Monteith (PM) method. In this study, the aim was (a) to propose a model for estimating ET0 and (b) to investigate its application together with alternative methods in an area of fruit production in the semi-arid region of Brazil. The Souza-Silva model was generated to estimate ET0 and together with other original methods based on thermal-water variables and global incident solar radiation was tested relative to the PM method. The Souza-Silva method (ET0SS = − 0.00728 + 1.356325DPV + 0.174658Qg, where VPD is the water vapour-pressure deficit and Qg the global incident solar radiation) showed excellent performance in estimating ET0 with a low level of error (RMSE = 0.467 mm day−1 and MBE = − 0.034 mm day−1). Among the original alternative methods, those for Hargreaves (ET0HS) and Camargo (ET0C) models did not perform well in the region under study. The Benevides and Lopes (ET0BL) and Valiantzas1 (ET0V1) methods gave excellent results; these were however even lower than methods based on the solar radiation. Compared to each of the original methods, the result of the Souza-Silva method showed greater precision and accuracy, with smaller estimation errors. It is concluded that this method, based on the water vapour-pressure deficit and solar radiation, can be used to estimate ET0 in places where data collection is limited. [ABSTRACT FROM AUTHOR]

Caatinga biome, located in the Brazilian semi-arid region, is the most populous semi-arid region in the world, causing intensification in land degradation and loss of biodiversity over time. The main objective of this paper is to determine and analyze the changes in land cover and use, over time, on the biophysical parameters in the Caatinga biome in the semi-arid region of Brazil using remote sensing. Landsat-8 images were used, along with the Surface Energy Balance Algorithm for Land (SEBAL) in the Google Earth Engine platform, from 2013 to 2019, through spatiotemporal modeling of vegetation indices, i.e., leaf area index (LAI) and vegetation cover (VC). Moreover, land surface temperature (LST) and actual evapotranspiration (ETa) in Petrolina, the semi-arid region of Brazil, was used. The principal component analysis was used to select descriptive variables and multiple regression analysis to predict ETa. The results indicated significant effects of land use and land cover changes on energy balances over time. In 2013, 70.2% of the study area was composed of Caatinga, while the lowest percentages were identified in 2015 (67.8%) and 2017 (68.7%). Rainfall records in 2013 ranged from 270 to 480 mm, with values higher than 410 mm in 46.5% of the study area, concentrated in the northern part of the municipality. On the other hand, in 2017 the lowest annual rainfall values (from 200 to 340 mm) occurred. Low vegetation cover rate was observed by LAI and VC values, with a range of 0 to 25% vegetation cover in 52.3% of the area, which exposes the effects of the dry season on vegetation. The highest LST was mainly found in urban areas and/or exposed soil. In 2013, 40.5% of the region's area had LST between 48.0 and 52.0 °C, raising ETa rates (~4.7 mm day−1). Our model has shown good outcomes in terms of accuracy and concordance (coefficient of determination = 0.98, root mean square error = 0.498, and Lin's concordance correlation coefficient = 0.907). The significant increase in agricultural areas has resulted in the progressive reduction of the Caatinga biome. Therefore, mitigation and sustainable planning is vital to decrease the impacts of anthropic actions. [ABSTRACT FROM AUTHOR]

Rainfall redistribution by forest cover has potential hydrological impacts in semi-arid regions due to continuous human intervention. Studying the process of interception loss by Caatinga vegetation and its changes due to deforestation is extremely important for local hydrology. However, such information is scarce in the literature. This study examined the partitioning of rainfall into throughfall (TF), stemflow (SF) and interception loss (I) in the Caatinga vegetation (CAA) and evaluated the influence of rainfall characteristics on this partitioning. The components of rainfall partitioning were measured from 2016 to 2017 to determine the TF and SF respectively, and their relationships with rainfall characteristics were evaluated based on linear regression models. For the Caatinga vegetation, TF and SF represent 89.2% and 0.5% of the gross rainfall, while interception loss was 10.3%, an expressive value that should be included in regional water balance models. The rainfall characteristics were able to explain the variations in water partitioning, showing that TF and SF increase for events of higher intensity and volume, whereas interception loss is mainly associated with events of longer duration. For the Caatinga, stemflow and throughfall usually occur for events of greater than 1.65 mm and 0.98 mm, while values for canopy water storage ranged from 0.88 mm to 1.16 mm. It is concluded that for semi-arid environments, these values are significant and cannot be ignored when managing local water resources. [ABSTRACT FROM AUTHOR]

[Display omitted] • Annually the flux of sensible heat is higher than latent heat. • Cactus carbon and nutrient stocks were particularly high. • Cactus had low evapotranspiration and high WUE in the dry season. • Rainfall influences the net exchange of carbon in the ecosystem. Anthropogenic disturbances directly influence environmental processes and increase the concentration of carbon (C) in the atmosphere. Here, we compare the differences in the seasonality of the balance of carbon, energy, and radiation, as well as seek to identify the interrelationships between these environmental variables and their impact on the growth of Opuntia cactus. Data were acquired from an eddy covariance flux tower over a cactus crop agroecosystem (2019–2021) in the Brazilian semi-arid region. In addition, we use plant growth rates, carbon and nutrient stocks, evapotranspiration (ET) and water use efficiency (WUE), and radiation (RUE). We show that the closure of the surface energy balance was 71%, although there are minimal fluxes of available energy lost (29%) by unquantified processes. At all seasons, the highest net ecosystem CO 2 exchange (NEE) rate was between 11:00–13:00 (−5.75 μmol m−2 s−1). During the dry and wet-dry season, there was the lowest daily gross primary productivity (GPP) (2.5 μmol m−2 s−1) and net radiation— R n (217.97 W m−2). Ecosystem respiration was more expressive during the wet season (2.41 μmol m−2 s−1), and maximum diurnal value of 2.65 μmol m−2 s−1. Furthermore, the latent heat flux was higher during the wet season (114.68 W m−2) and lowered in the dry season (9.39 W m−2). The net assimilation rate showed higher values during the dry-wet transition. The dry season presented higher nutrient use efficiency and WUE (14.77 g m−2 mm−1). The highest ET occurred during the wet season (227 mm), and RUE was 81.48% higher than in the dry season. Overall, the cactus was a potential C sink during the three years of assessment (NEE: −377 g C m−2 year−1; GPP: 881 g C m−2 year−1). The results help us to understand that most of the R n energy is used in the sensible heat flux (58% ratio). [ABSTRACT FROM AUTHOR]

• Landscapes exhibit significant differences in micrometeorological variables. • Removing native vegetation reduces the net radiation on the landscape. • The evapotranspiration (ET) is lower in the cactus landscape. • Land use change does not affect the seasonality of energy fluxes. • Variation in water and energy availability affects ET more than landscape type. The comparison of energy exchanges between different landscapes is very valuable for understanding the consequences of deforestation and land use change on the climate. In this study, we analyzed micrometeorological variables, energy fluxes, and actual evapotranspiration over four landscapes of the Brazilian semi-arid region (preserved Caatinga – CAA, regenerating Caatinga – REGE, cactus landscape – CAM and deforested landscape – DEFA). Micrometeorological measurements (air temperature and relative humidity, vapor pressure deficit), net radiation (R N), latent heat (LE), sensible (H) and soil heat (G) fluxes, actual evapotranspiration (ET), and soil water storage variation (Δ S) were obtained in landscapes from October 2018 to September 2020. LE and H were calculated based on the Bowen ratio method. Significant differences were noted between micrometeorological variables (temperature and relative humidity, and vapor pressure deficit) and energy flux among the four landscapes. The four surfaces exhibited, on average, lower LE values when compared to H. At CAA landscape, 35% of the R N was used for LE, 64% for H, and 1% for G, versus 33% for LE, 65% for H, and 2% for G at REGE; 33% R N for LE, 65% for H and 2% for G at CAM, and 40% for LE, 59% for H and 1% for G at DEFA. The evapotranspiration for regenerating Caatinga (1.62 mm day−1), cactus (1.59 mm day−1), and deforested area (1.90 mm day−1) were higher than the preserved Caatinga (1.40 mm day−1). However, seasonal variations of the ET were more associated with fluctuations in R N , rainfall, and Δ S than with the type of land use. It is concluded that the removal of Caatinga by landscapes such as regenerating Caatinga, cactus plantations, and deforested area significantly modifies micrometeorological variables, energy fluxes, and the evapotranspiration, but their seasonality depends on the regime availability of water and energy. [Display omitted] [ABSTRACT FROM AUTHOR]

Hostile climatic conditions, including high water deficit in the soil-atmosphere system characterize regions with arid and semi-arid climates. Local landscapes with climates of low rainfall and relative humidity, and high air temperature, such as regions of sub-humid, semi-arid, and arid zones, cover approximately 45.4% of the entire land surface of the planet, to which the biomes with dry forests occupy a total area of 1079 × 104 km2. Thus, this review aims to quantify the processes and changes in energy, water, and carbon fluxes and their interactions with the surfaces of terrestrial ecosystems of Caatinga and cacti in semi-arid environments. Studies report that forests in arid and semi-arid environments show resilience to local diversity, prominent in the interrelationship of species, which favors the survival of individuals with changes in the ecological niche. One of the main modifications in land use and land occupation in dryland landscapes is the implementation of agriculture. There is evidence that poor land use can negatively affect soil carbon stocks. Furthermore, carbon and energy fluxes in terrestrial ecosystems undergo significant changes with the removal of native vegetation. Therefore, the damage caused by deforestation can cause severe problems in the energy and carbon balance, compromising species' survival. Finally, we emphasize that crassulacean acid metabolism plants can be an alternative in places with serious environmental degradation problems. • CAM plants can be an alternative in places with degradation. • Drought-adapted plants synthesize bioequivalent biomass with less moisture. • The Caatinga forest is an important carbon sink. • The Caatinga makes an important contribution to the carbon and water cycle. [ABSTRACT FROM AUTHOR]

Water scarcity is a problem that affects agricultural production around the world. Increasing forage production in the semiarid region is necessary to maintain animal production, and consequently food security. Different agronomic management can improve growth and productivity responses and the water-economic indexes of the crop. Therefore, this study aimed to evaluate how the management of density and orientation of forage cactus plantations modify the morphophysiological indices, phenophases, cutting moment, productivity, soil water balance, and water-economic indicators in a semiarid environment. The study was carried out during two harvests (2020–2021 and 2021–2022) in the Brazilian semiarid region. Three experiments were conducted with the 'Orelha de Elefante Mexicana' clone under a randomized block design and four replications. Two experiments were composed of five planting densities (100,000, 50,000, 33,000, 25,000, and 20,000 plants ha−1) modified by the spacing between plants (0.10, 0.20, 0.30, 0.40, and 0.50 m with a fixed distance of 1.00 m between rows), the first with East-West (EW) orientation and the second with North-South (NS) orientation. The third experiment presented four planting densities (50,000, 40,000, 33,000, and 28,571 plants ha−1) modified by the distance between rows (1.00, 1.25, 1.50, and 1.75 m with a fixed distance of 0.20 m between plants). Biometric and biomass data were used to determine morphophysiological indices, delimitation of phenophases, ideal cutting moment, and fresh matter (FM) and dry matter (DM) productivity. The soil water balance was carried out using soil moisture readings and the physical-water properties, and the crop's water-economic indices were calculated. In general, morphophysiological indices, phenophases, and cutting moments were affected by densities (p<0.05). DM productivity was 16 % higher in the EW orientation (27.7 Mg ha−1) compared to the NS orientation. The highest planting density (100,000 plants ha−1) in the 1.00 × 0.10 m arrangement presented the highest averages of FM and DM of the cycles, being 401.5 and 32.4 Mg ha−1 orientation EW and 420.8 and 29.5 Mg ha−1 orientation NS. Density of 50,000 plants ha−1 in the 1.00 × 0.20 m arrangement (265.5 and 23.5 Mg ha−1 of FM and DM, respectively). This same behavior occurred for water and economic indices. Therefore, higher densities in forage cactus cultivation (100,000 plants ha−1 in the East-West planting orientation and 50,000 plants ha−1) must be adopted to enhance forage production in semiarid regions. [Display omitted] • Morphophysiological indices of forage cactus by densities and cultivation orientation. • Higher cropping densities have high forage production in arid and semiarid regions. • Higher crop densities present greater water-economic efficiency. • The soil-plant relationship was influenced by different experimental arrangements. [ABSTRACT FROM AUTHOR]

A mosaic of landscapes can be seen in the semi-arid region of Brazil as a result of anthropogenic activity (i.e. deforestation). These changes can lead to a reduction in soil carbon (C) and nutrient stocks, especially in arid and semi-arid regions. With this in mind, was evaluated both C and nutrient stocks dynamics in various landscapes in the semi-arid region of Brazil under different levels of anthropogenic intervention, including landscapes of preserved Caatinga (CAA), regenerating Caatinga (REGE) and deforested Caatinga (DEFA) located in the municipality of Floresta, Sertão of Pernambuco, and landscapes of the following forage cactus clones: 'Orelha de Elefante Mexicana' - Sertão (OEM-S), 'Orelha de Elefante Mexicana' - Agreste (OEM-A), and 'IPA-Sertânia' - Agreste (IPA-A) these last two located in the municipality of Pesqueira, Agreste of Pernambuco. Soil samples were collected at four depths (0–10, 10–20, 20–30 and 30–40 cm) and the physico-chemical (field capacity, bulk density, particle density, total porosity, sand, silt and clay) properties and stocks of C, P, K+, Ca2+, Mg2+ and Na+ were quantified. Data were analysed using the Kruskal-Wallis test and Conover-Iman mean test (for k samples) (p <0.05). The carbon stock was highest in forage cactus clone landscapes (OEM-A) with an average of 58.9 Mg ha−1, while the lowest stocks were observed in the CAA, DEFA and OEM-S landscapes with average values of 28.6, 23.74 and 23.3 Mg ha−1, respectively. Similarly, the highest P stock was recorded for OEM-A (0.4 Mg ha−1), while for the other landscapes P stocks were lower. The highest stocks of K+ were seen in REGE (0.90 Mg ha−1), while Ca2+ stocks showed no difference between CAA, REGE or OEM-A, with mean values of 6.5, 6.4 and 5.3 Mg ha−1, respectively. Therefore, in this study was found that stocks of C and nutrients decrease with increasing depth, so that these stocks tend to be higher during seasons when more water is available in the soil. Furthermore, the area that included the 'Orelha de Elefante Mexicana' clone in the Agreste region, showed a greater capacity for storing carbon and phosphorus. [Display omitted] • C stocks are higher in forage cactus areas than in the Caatinga areas. • Stocks of C and nutrients increase with the availability of water in the soil. • The regenerating Caatinga landscape stores, an average of 0.90 Mg K ha−1. • C, P, K stocks decrease with increasing depth in six landscapes. [ABSTRACT FROM AUTHOR]

Soil and climatic conditions limit forage production in semi-arid environments. Planting crops adapted to these elements, combined with management practices such as intercropping and irrigation, can ensure the sustainability of animal feed. The aim of this study was to evaluate growth, forage productivity, soil water balance, water indices and the indices of biological efficiency, competitive ability, and economic return in a dense crop of forage cactus, grasses, and legumes under single and intercropping systems in a semi-arid environment. The study was carried out from 2020 to 2022 in Serra Talhada, Pernambuco, Brazil. The plants used were the 'Orelha de Elefante Mexicana' (OEM) clone of the forage cactus, pigeon pea ('crioula'), millet ('Bulk-01') and sorghum ('SF15'). A randomised block design was adopted, with three repetitions, including single crops of the forage cactus, sorghum, millet and pigeon pea, as well as the cactus intercropped with pigeon pea, millet and sorghum. Biometrics and biomass were checked to determine morpho-physiological indices, phenology, cutting time, biological efficiency and competitive ability. The soil moisture was also monitored, and the soil water balance quantified. The water indices and economic return were then calculated. Growth rates and phenology were not affected by intercropping, only by the cutting time. During the first season, the single sorghum and cactus-pigeon pea system showed a variation in soil water storage of 26 mm, while during the second season, the single cactus stored 66.74 mm. The actual evapotranspiration ranged from 1109 in the cactus-millet system to 1152 mm in the single cactus and millet (1st season), and from 1510 in the single cactus to 1570 mm in the sorghum (2nd season). The cactus-sorghum system was the most productive, with 460.53 Mg FM ha−1 and 43.55 Mg DM ha−1 in season one, while in season two, the single cactus obtained 237.64 Mg FM ha−1 and 26.71 Mg DM ha−1. Intercropping promotes more productive stability and feed diversity, as well as greater biological efficiency, competitive ability and economic return. Understanding the changes that exist in a intercropping system is important, especially in semi-arid regions, since these have distinct characteristics that impact the development of crops. Thus, this work contributes comprehensively to resilient practices for the semi-arid, seeking to ensure the sustainability of the intercropping systems and understand the interrelationship between species from the management adopted. [Display omitted] • The phenology and growth of the forage cactus were not influenced by intercropping, only the moment of cut. • Monocultures stored larger volumes of water in the soil. • Sorghum 'SF15' is the secondary crop with the highest productive potential, either in monoculture or in intercropping. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the effect of different controlled water regimes on the morphophysiological indicators, phenophases, and ideal cutting time of forage cacti clones grown in a semiarid environment. From 2016 to 2018, in the semi-arid region of Brazil, the Miúda (MIU), Orelha de Elefante Mexicana (OEM) and IPA Sertânia (IPA) clones were submitted to three regimes (40%, 80% and 120% ETc, where ETc is crop evapotranspiration) and to rainfed conditions (0% ETc). Cladode area index and the dry matter yield (DM) were used for calculating the morphophysiological indices. The cladode emission aided in delimiting the phenophases and, based on the DM accumulation, defined the ideal time for cutting the crop. The OEM clone excelled in terms of dry matter accumulation with a maximum value of 0.0441 Mg ha−1 °Cday−1. The water regimes above 80% ETc rise the number of phenophases in MIU and IPA clones. Cultivating forage cactus under water regime up to 40% ETc for OEM (895 °Cday) and 80% ETc for MIU and IPA (737 °Cday and 708 °Cday, respectively) anticipates the harvest time. Thus, a controlled reduction in the amount of water no negatively impact the growth dynamics, phenology, or cutting time. • Water regimes changes morphophysiology, phenophase and cutting time of cactus clones. • Cactus O. stricta proved to be more efficient in accumulating dry matter. • Phenophase 2 showed greater sensitivity to increases in the water amount. • Cutting time showed variations due to the clones and, water regimes. • Controlled water deficit brings forward the harvest time of the cactus clones. [ABSTRACT FROM AUTHOR]

The intercropping systems of species adapted to conditions of water deficit, such as sorghum (Sorghum spp.) and forage cacti (Nopalea spp. and Opuntia spp.), can contribute to an improvement in the biomass yield of semi-arid agricultural areas. This study aimed to evaluate the performance of intercropping cactus and sorghum as well as the biological efficiency and competitive ability of forage cactus clones and sorghum cultivars. The experiment was carried out in the Brazilian semi-arid region, in a randomised block design with 15 treatments and four replications. The treatments consisted of three forage cactus clones ('IPA Sertânia'—IPA, 'Miúda'—Miu and 'Orelha de Elefante Mexicana'—OEM) and three sorghum cultivars ('467', 'SF11' and '2502') under single configuration and the maximum number of combinations to comprise the intercropping systems. In terms of fresh and dry matter (221.73 and 47.04 Mg ha−1, respectively), the cactus-sorghum intercropping was 47% and 3.5 times more productive in terms of fresh and dry matter than the cactus single systems, with no effect on the quality of the forage. The forage cactus clones were dominant over the sorghum cultivars. The OEM-'467' configuration offered better stability (lower mortality), biological efficiency and crop competitiveness when compared to the single systems. [Display omitted] • Forage production via intercropping is vital for decreasing forage seasonality. • The intercropping does not alter the bromatological composition of the system. • Specific combinations between forages were more efficient. • The intercropping with Opuntia presented better cactus planting establishment. [ABSTRACT FROM AUTHOR]

The application of nitrogen fertilization can promote different morphological, productive, and efficient responses in forage cactus. Therefore, the objective was to determine the morphophysiological, productive, nutritional, and economic responses of the forage cactus clone Orelha de Elefante Mexicana (Opuntia stricta (Haw.) Haw.) subjected to four doses of nitrogen (N) under irrigated conditions in the semi-arid region. Four treatments were applied: 50 (T1), 150 (T2), 300 (T3), and 450 (T4) kg ha−1 of N. For growth analyses, biometry and biomass data were collected to determine phenology, rates morphophysiological characteristics, ideal cutting time, and fresh (FM) and dry (DM) yields. From data on soil moisture, physical-hydric properties, and productivity, the components of water balance, water use efficiency, and economic gain of the crop were calculated. From analyzes of forage cactus plant tissue, nutrient concentrations, biological utilization coefficient, and nutrient use efficiency were determined. The FM and MS yields showed a quadratic (cycle 1 and 2) and positive linear (cycle 3) response to the increase in nitrogen dose. In the first two cycles the maximum dose for FM was 286.19 kg N ha−1 and 413.33 kg N ha−1, to DM productivity the maximum dose was 299.12 kg N ha−1 and 416.79 kg N ha−1. The specific cladode area and the net assimilation rate had better responses at the lowest N doses (50 and 150 kg ha−1), and the absolute and relative growth rate, phenology, and cutting moment were under little influence of N levels. The concentrations and the coefficient of biological utilization of the nutrients showed a positive response to the quadratic model. For concentrations, nitrogen (T4 = 6.72 g N kg−1 DM), phosphorus (T1 = 6.28 g P kg−1 DM), and potassium (T1 = 33.18 g K kg−1 DM) showed significance at 5 % probability, and the quadratic model accounted for 99 % of the data variability. It was concluded that the clone characteristic influenced the relative and absolute growth rates more than the different nitrogen doses. Fertilization from 300 kg N ha−1 increased DM and FM productivity and nutrient concentrations. Lower doses of N were more efficient in DM production. Based on real evapotranspiration, N use efficiency increased with increasing doses, and for other nutrients, the greatest efficiencies occurred in cultivation periods with a smaller amount of water inserted into the system. [ABSTRACT FROM AUTHOR]

• The AquaCrop proved to be efficient and applicable for semi-arid regions. • Improved performance of AquaCrop for simulating crops without using mulch. • AquaCrop excels in calibrating/validating forage plant systems efficiently. Understanding the best strategies for growing forage plants is important in balancing livestock production, as is the improvement of management techniques aimed at increasing food production. Models that simulate plant growth are therefore important tools for agricultural planning. The aim of this study was to calibrate and validate the AquaCrop model for agricultural systems of the forage cactus, millet and sorghum under different production arrangements. Twelve production units were cultivated from 2019 to 2020, using different cactus clones, and millet and sorghum cultivars, with variations in crop configuration, ground cover, water regime and crop density. Data on the crops (phenology, biometry and biomass throughout the cycle, and productivity at harvest), climate, irrigation, soil and management were observed. In all, data from six production units were used for calibration and six for validation. The performance of the model was evaluated using statistical indices. AquaCrop resulted in admissible errors in predicting the productivity of the crops under evaluation, showing good accuracy with a coefficient of determination greater than 0.80 and performance classified as 'very good' (confidence coefficient > 0.80). The Orelha de Elefante Mexicana clone showed the highest mean water productivity (39 g m −2). It was concluded that the model can be used to simulate crop productivity under different cropping arrangements in agricultural environments in the semi-arid region of Brazil with the aim of meeting the forage deficit of livestock in the region. [ABSTRACT FROM AUTHOR]

1. CONTEXT - Improving the use of natural resources (e.g., water, nutrients, and radiation) within production systems under different technologies (mulch and intercropping) is fundamental to intensifying sustainable agriculture. 2. OBJECTIVE - The objective was to quantify the parameters of water consumption and the efficiency of using natural resources of forage cactus and millet under different technologies of crops in a semiarid environment. 3. METHODS - The forage cactus (clone Orelha de Elefante Mexicana) and millet (cv. IPA Bulk-1-BF) were evaluated to six cropping arrangements: single cactus with mulch (CWM), single cactus with no mulch (CNM), single millet with mulch (MWM), single millet with no mulch (MNM), a cactus-millet intercropping system with mulch (CMWM), and cactus-millet intercropping system with no mulch (CMNM). Data on crop growth, crop production, and soil moisture were collected, and the following were determined: crop evapotranspiration (ET c), crop transpiration (T), soil water evaporation (E), single crop coefficient (K c), dual crop coefficient (K cb and K e), water use efficiency (WUE), nutrient use efficiency (NUE) and radiation use efficiency (RUE). Biological efficiency and competitive ability indicators were calculated for the intercropped systems. 4. RESULTS AND CONCLUSIONS - The ET c (mm day −1) was higher under MWM (4.69), MNM (3.60), and CMWM (3.81). There was little variation in the values of ET c , T, or E between CNM and CWM, unlike between MNM and MWM. Intercropping reduced E compared to the single crops of cactus (8%) and millet (58%). On average, K c was higher under MWM (0.98), CWM (0.69), and CMWM, (0.88), compared to MNM (0.75), CNM (0.63), and CMNM (0.48). The intercrops were more efficient for WUE (44%) and RUE (2.28 g MJ −1), with no difference for NUE. It can be concluded that the cactus-millet intercropping system is a good alternative for more-resilient agriculture in semi-arid environments, especially when the use of mulch. 5. SIGNIFICANCE - The results of this study are significant for the management of water resources in the semi-arid region, as they favour knowledge of the water needs of these crops in different production systems, and how the adoption of technologies such as intercropping and mulching can improve efficiency in the use of available natural resources, compared to exclusive planting. [Display omitted] • The best water use efficiency in intercropping is independent of the mulch. • Intercropping reduces soil evaporation by up to 58% compared to monoculture. • Mulch influences the variation of T and E in millet monoculture but not cactus. • Crop coefficients (K c) were higher in systems with mulch. • The adoption of cactus/millet intercropping is viable for the semiarid region. [ABSTRACT FROM AUTHOR]

• Caatinga deforestation by bare soil affects the soil properties. • Successive years of agricultural practices affected soil bulk density and total porosity. • Farmland abandonment has affects pH, and the content of various chemical elements. • Caatinga deforestation increases the minimum temperature, and vapor pressure deficit. • It is very likely that Caatinga removal promotes a reduction in precipitation. The Brazilian semiarid region has been subjected to strong man-made actions since the 1970s, which have resulted in landscape transformation. The scientific literature presents several studies on the soil properties or microclimate of different types of landscapes; however, less attention was having been paid to the surface contrast between native vegetation and bare soil. The objective of this research was to evaluate the soil properties and microclimate of two common landscapes in the Brazilian semiarid region, a seasonally dry tropical forest (Caatinga) and a deforested area. Soil and microclimate data were obtained from two sites, both located in the State of Pernambuco, Brazil. Soil samples were collected on six dates and from layers, and microclimate variables were measured for three years. Soil properties and microclimatic data were evaluated using the Mann-Whitney test, as well as regression and principal component analysis. Successive years of agricultural practices affected the bulk density, promoting an increase in the total porosity of the soil in the deforested area site. In addition, changes were verified in the magnitude of many chemical properties (pH, P, K+, Mg2+, Cu2+, Fe, Mn, Zn2+ and Ca2+), indicating soil degradation. Compared with the Caatinga forest site, the minimum air temperature was 2.3 °C, and the maximum vapor pressure deficit was 7% higher in the deforested area site, and it is very likely that Caatinga removal there will lead to a reduction in precipitation. The results suggest that Caatinga vegetation removal followed by agricultural practices and subsequent land abandonment promotes significant changes in soil properties and the microclimate, which can contribute to advances in desertification and affects agricultural activities in the Brazilian semiarid region. [ABSTRACT FROM AUTHOR]

• Capacitive probes calibration showed good results under different land uses. • Changes in land use influence the spatial and temporal variability of θv. • The deforestation of the caatinga reduces the θv in 47%. • Converting the Caatinga for forage cactus decreases the reduction of θv for 26%. • It is recommended to establish forage cactus in already deforested areas. The semiarid region of Brazil undergoes constant changes in land use due to the process of deforestation and high water seasonality, represented among other variables by a decline in the soil moisture content. In this study, the influence of land use on the soil moisture dynamics is analysed. For this purpose, three experimental sites were evaluated, characterised by different types of land use: an agroecosystem of forage cactus, a deforested environment and an area of Caatinga vegetation, located in the semiarid central hinterlands of Brazil. Calibration of the Diviner2000® capacitive probes was carried out using the relationship between the soil volumetric moisture content (θv), obtained by the gravimetric method, and the relative frequency readings of the probes. Weekly measurements of the moisture content were taken at 22 points at depths of 0.00–0.60 m from November 2014 to October 2017, providing 157 sampled days. The mean values and standard deviations of the θv variable for the three surfaces were analysed over twelve periods, and grouped according to the local water regime into rainy, dry and transitional. To analyse the temporal stability of θv, the relative difference and the Spearman correlation matrix were calculated. Finally, multivariate principal component analysis (PCA) was used to identify associations between the mean values of θv and physical properties in the different soil layers. Based on the results, the local calibration curves presented significant coefficients of determination, showing that the equations can be used for reliable estimates of θv. The θv was higher in the Caatinga (0.086 m3 m−3), intermediate in the forage cactus (0.064 m3 m−3) and lower in the deforested area (0.045 m3 m−3). Changes in land use influence the spatial variability of θv in the soil layers, which responded to the local rainfall regime, especially in the upper layers (0.05–0.25 m). Significant differences in θv between soil surface coverage occurred during the dry sub-periods and the transition periods, when the Caatinga was superior to the other areas. The temporal stability analysis identified the forage cactus area as the most representative location for θv estimates, while the Spearman correlation matrix detected the more-unstable areas of moisture, with persistent moisture patterns between the dry sub-periods and transition periods only. Associations between moisture and different soil properties were affected by soil surface coverage and soil layer depth. All the proprieties explained moisture distribution along the profile. It can be concluded that converting the Caatinga vegetation into other soil surface coverages changes soil-moisture distribution patterns, resulting in a reduction in θv of 26% and 47% for forage cactus and deforested areas, respectively. Therefore, the establishment of forage cactus in current deforested areas of the Brazilian semiarid may attenuate the temporal variability and reduction of soil moisture compared to bare soil surfaces. [ABSTRACT FROM AUTHOR]

• Litterfall peaks of Caatinga domain occurred in the months of March to July. • The leaf structure contributes more than 53% of litterfall. • Litterfall seasonality varies among types of plant species. • Meteorological elements variation strongly explains the seasonality of litterfall. • Caatinga domain deposits 0.637 ton. MS ha−1. The Caatinga Domain is exclusively Brazilian, covered by vegetation exhibiting a great diversity of species, which have morphological and physiological characteristics determined by environmental conditions. These attributes define quantity and quality litterfall deposition on the soil. The litterfall deposition seasonality was monitored a fragment of Caatinga vegetation, located in the semiarid region of Brazil, from 2016 to 2017. The decomposition rate, mean residence time for litterfall (50 and 95%), and the exportation of mineral nutrients via deciduous material were determined. Data from meteorological variables and litterfall were used in the elaboration of Pearson's correlation matrix, and multicollinearity, canonical and path analyzes. The Caatinga deposited on average 637 kg DM (dry mass) ha−1 year−1 litterfall, including 53% leaves, 26% twigs, 15% reproductive structures and 6% miscellanea, with deposition peaks between the months of March and July, with values above 57 kg MS ha−1. Global solar radiation, vapor pressure deficit, soil heat flux, rainfall and normalized difference vegetation index are controlling factors the litterfall deposition. The decomposition rate of the litterfall was 0.33 kg DM ha−1 year−1, while the time required for the disappearance of 50% and 95% of the litterfall was respectively 2.1 and 9.1 years, and the exportation of nutrients was 13.59 kg ha−1 year−1. Litterfall deposition was determined by the environmental conditions and physiological responses of the vegetation, which are fundamental to maintaining the Caatinga Domain. [ABSTRACT FROM AUTHOR]