Summer Rainy Season Research Articles

Temporal variation in local wetland hydrology influences postdispersal survival of juvenile Wood Storks (Mycteria americana)

Since the 1960s, anthropogenic shifts in the timing and distribution of surface-water flows in the Everglades have pushed back the onset of reproduction in Wood Storks (Mycteria americana). Late nesting increases the probability that juveniles leave the colony during the summer rainy season, when water levels are high and prey animals unavailable. We used satellite telemetry to track firstyear survival of 85 Wood Storks from southern Florida over 4 years. We further evaluated survival in relation to hydrologic and physiologic variables, including water depths, surface-water recession rates, May rainfall, use of wetland habitats, sex, total feather mercury, whiteblood-cell counts, and heterophih:lymphocyte ratios for a subset of 71 birds, using a known-fates model in Program MARK. Juveniles that dispersed from the colony during favorable conditions (surface water depths <25 cm) had a first-year survival rate of 0.37 ± 0.06 (SE), compared with 0.15 ± 0.04 for those that dispersed into unfavorable conditions (depths >25 cm). General hydrologie conditions (favorable vs. unfavorable), wetland habitat use, and white-blood-cell counts were the best predictors of monthly survival, and the strongest effects were associated with the first month postdispersal. Our study is the first to show a relationship between temporally fluctuating hydrologic variables and survival of juvenile Wood Storks, highlighting the need to consider the timing of hydrologic manipulations when managing wetlands for birds. We conclude that human-induced changes in the temporal patterns of hydrology may have important consequences for the phenology and, ultimately, the demography of wetland birds.

Spatiotemporal Characteristics of Drought Occurrences over Japan

AbstractThe drought climate of Japan from 1902 to 2009 was analyzed using an effective drought index (EDI). Drought regions were identified by hierarchical cluster analysis using drought characteristics (duration, severity, and onset and end dates) obtained from 50 observation stations. The results indicated that droughts could be divided into four groups (G1–G4) that reflected the local climate. The four groups were related to precipitation as follows. The summer rainy season affected groups G2–G4, in which droughts occurred mainly during spring and summer and were relieved before and after the rainy season. The G1 group was not affected by the summer rainy season and droughts were spread evenly throughout the year; it even had cases of droughts relieved by winter snow. All groups included dry conditions over the 108-yr period, and the driest conditions occurred in the late twentieth century. The statistical analysis of drought data showed that a total of 23 country-wide droughts occurred and that the most extreme droughts occurred in 1939–41 and 1984–85, with an EDI of −1.55. In addition, four dry seasons (1939–45, 1997–98, 1994–97, and 2005–09) were found using regime shift analysis. Regional droughts occurred 54, 54, 49, and 59 times in groups G1–G4, respectively. On average, short-term droughts with a duration shorter than 6 months occurred 3.5 times per decade, whereas long-term droughts extending over 1 yr occurred 0.3 times per decade. The drought duration and intensity were used to calculate the statistical return period of country-wide droughts. The 1939–41 drought had the longest return period, at 104.7 yr. The 1987–88 and 1995–97 droughts had return periods of 65.9 and 65.5 yr, respectively.

Climatological Evolution of the Okinawa Baiu and Differences in Large-Scale Features during May and June

Abstract The Okinawa baiu (summer rainy season) starts in early May and ends in late June, preceding the baiu in mainland Japan by approximately 1 month. This study investigates the time evolution of the large-scale circulation associated with the Okinawa baiu using 10-yr (1997–2006) climatologies of precipitation and meteorological fields, with particular focus on temperature advection at 500 hPa.The onset of the Okinawa baiu occurs in early May and is followed by an initial peak in precipitation during mid-May. The baiu rainband then moves southeastward, leading to a short break in baiu precipitation during late May. The rainband returns to Okinawa in early June, and a second peak in precipitation occurs during mid-June. The baiu rainband withdraws northward in late June. The mid-May precipitation peak is associated with warm advection at 500 hPa, mainly due to the meridional temperature gradient and the prevailing southerly winds. This warm advection coincides with upward motion near Okinawa; however, the warm advection is insufficient to explain the peak precipitation amount. Enhancement of precipitation by a transient disturbance probably contributes to the peak amount. The break period during late May coincides with the peak of South China Sea monsoon. Warm advection at 500 hPa strengthens again in June because of the strong zonal thermal contrast between the warm Tibetan Plateau and cold Pacific. This warm advection is able to adequately explain both the upward motion and precipitation. These results indicate that the large-scale meteorological characteristics are different during the first and second peaks.

Who controls the monthly variations of NH4+ nitrogen isotope composition in precipitation?

Nitrogen isotopes of ammonium (δ15N–NH4+) in precipitation have been analyzed, to study their monthly variations, from Oct. 2008 to Sep. 2009 at Guiyang, Southwest China. δ15N–NH4+ values were higher in winter and lower in summer showing a strong sine curve. In summer (rainy season), raindrop may remove more light ammonia by washout process, because raindrop incorporated 15NH3 preferentially while left the 14N in the atmosphere. At the same time, longer sunshine times imply more hv for producing H2SO4 of SO2 to H2SO4, which accelerates gaseous to particle conversion of NH3 to (NH4)2SO4 by unidirectional reactions for isotopic enriched 14N. The above two aspects can somewhat cause the seasonal variation of nitrogen isotopic composition, but are not the main or direct reasons. The temperature has an opposite trend with seasonal variation of δ15N values. The temperature not only causes seasonal variation of δ15N values, but also increases the volatilization rate of NH3 and microbial activities. And there is a robust linear relationship between temperature and δ15N, showing that the temperature is the main factor to decide the monthly variation of δ15N–NH4+.

Long-term variability in onset and withdrawal of summer rainy season in the Philippines since the early 20th century

Long-term variability in onset and withdrawal of summer rainy season in the Philippines since the early 20th century

Seasonal variation of diurnal and semidiurnal rainfall over Southeast China

Diurnal (S1) and semidiurnal (S2) oscillations are major factors in determining the sub-daily variations of precipitation amount over Southeast China (PSEC). Most studies have examined the causes of S1(P)SEC and S2(P)SEC in the summer rainy season. However, causes of the seasonal changes in S1(P)SEC and S2(P)SEC have not been well documented. This study therefore examines possible mechanisms behind various precipitation types/cloud types because different types of precipitation/clouds control PSEC in different seasons. Results indicate that the variation of S1(P)SEC in winter, which tends to peak in the early morning, is mainly controlled by the high-relative-humidity-induced diurnal variation of non-showery precipitation/middle-level clouds. For S1(P)SEC in the other seasons, which tends to peak at the late afternoon, the moist-convection-induced diurnal variation of showery precipitation/low-level clouds is the main cause. Analyses also suggest that the phase of S2(P)SEC does not vary seasonally because both of its formation mechanisms—the semidiurnal variation of relative humidity and moist convection process—have similar phase evolution in all seasons. Seasonal changes in the water vapor supply to the maintenance of S1(P)SEC and S2(P)SEC are also discussed.

Soil Salinity and Quality of Sprinkler and Drip Irrigated Warm‐Season Turfgrasses

A study was conducted in New Mexico from 2005 to 2007 to investigate the effects of two potable water‐saving strategies, irrigating with saline water and using subsurface systems, on changes in rootzone salinity and quality of nine warm‐season turfgrasses. Plots were irrigated using either sprinklers or subsurface drip with water of 1 of 3 salinity levels (0.6, 2.0, and 3.5 dS m−1). Plots were rated monthly for quality during the growing seasons and bi‐annually for spring and fall color. Soil samples were collected bi‐annually (June and November) and analyzed for electrical conductivity (EC), Na, and sodium adsorption ratio (SAR) at depths of 0 to 20 and 50 to 60 cm. Electrical conductivity and Na values in 0 to 20 cm peaked in June of 2005 and 2006 and dropped to lower levels after the summer rainy season. With the exception of moderately saline irrigated plots in 2005, summer EC did not differ between drip and sprinkler irrigated plots for any of the three water qualities. Electrical conductivity, Na, and SAR at a rootzone depth of 0 to 20 cm were highest in June 2006 reaching 4.7 dS m−1, 1024 mg L−1, and 16.1, respectively. For most of the grasses tested, EC, Na, or SAR values showed no significant relationship with turf quality. Drip irrigation resulted in earlier green‐up than sprinkler irrigation but had no effect on summer quality or fall color retention. Most of the warm season grasses included in this study maintained an acceptable quality level when drip‐irrigated with saline water.

Tillage and crop residue effects on rainfed wheat and maize production in northern China

Dryland farming in the dry semi-humid regions of northern China is dominated by mono-cropping systems with mainly maize (Zea mays L.) or wheat (Triticum aestivum), constrained by low and variable rainfall, and by improper management practices. Addressing these problems, field studies on tillage and residue management for winter wheat and spring maize were conducted at 4 sites in Linfen, Tunliu and Shouyang (Shanxi province) and Luoyang (Henan province). These studies (a.o.) explored the impacts of different tillage and residue application methods on soil physical conditions, water storage, water use, water use efficiency (WUE) and crop yields of wheat and maize. An analysis of the results of these studies is presented. Conservation tillage, comprising no-till as well as reduced tillage practices (subsoiling, deep ploughing) showed benefits which were more prominent in combination with residue application. Benefits compared to conventional tillage were found in the form of improved soil physical conditions, such as higher topsoil bulk densities but lower subsoil bulk densities. This resulted in a better water storage during the summer fallow or rainy season in winter wheat fields, and a better water conservation and soil protection in spring maize fields. Compared to conventional methods, reduced tillage gave yields around 13–16% higher in spring maize and round 9–37% higher in winter wheat. Yields under no-till were very close to those from conventional methods. Surface application of crop residue for maize was found to increase the risk for delayed seedling emergence, because of low temperatures, leading to a recommendation for incorporation of residue in combination with reduced tillage. For winter wheat, subsoiling in combination with straw mulching after harvest in summer every other two or three year, and no-till seeding is a promising practice for sandier soils and low rainfall conditions. For heavier clay loam soils, deep ploughing with straw mulching after wheat harvest in summer every other two or three year, and no-till seeding practice is recommended. For spring maize, deep ploughing with straw and fertilizers incorporation after harvest in fall, and no-till seeding practices are recommended. Subsoiling or no-till with residue mulching after harvest in fall, and no-till seeding practices in spring are also promising practices, the latter only in situations where low spring temperatures are not a problem. Continuous no-till is not recommended.

Onset of East Asian subtropical summer monsoon and rainy season in China

Here we use harmonic analyses to examine seasonal variations of China land rainfall, low-level winds, and atmospheric heating over East Asia during spring to summer and the associated subtropical summer monsoon activities. Our results indicate that the South China spring rainfall (SCSR) in March is the prophase of East Asian sub-tropical summer monsoon (EASSM), and the onset of EASSM and China summer rainy season starts in early April, characterized by the enhanced rainfall in South China and the seasonal reverse of zonal land-sea thermal contrast in sub-tropical East Asia. The EASSM onset is earlier than that of South China Sea summer monsoon, and it is active in east of 100°E and north of 20°N. Our analyses suggest that the subsequent heating appears over India-China Peninsula in March and South China in April and causes the low-level atmospheric warming and the zonal land-sea thermal contrast seasonal reverse in East Asian subtropics. The atmospheric heating over South China is the main force to drive the southwesterly winds, updrafts and strengthen the summer precipitation in South China.

Common and distinct responses in phytohormone and vitamin E changes during seed burial and dormancy in Xyris bialata and X. peregrina

Temperature and humidity are the main factors influencing seed viability, dormancy and longevity of buried seeds. Unfortunately, very little is known about such processes in species of tropical regions, where temperature does not show major seasonal variations. The extent to which germination capacity, phytohormones and vitamin E levels were altered after burial of seeds of Xyris bialata and X. peregrina (Xyridaceae), two species endemic to rupestrian fields of Brazil, was examined. After 2 months of burial, seed germination capacity remained constant, which is associated with decreases in ABA and IAA content in both species. During this period, zeatin levels also decreased in X. bialata, but not in X. peregrina, the latter showing much lower levels of ABA. During the summer (rainy season), seeds of both species experienced a progressive, but severe, decrease in germination capacity, which reversed at the end of the winter (dry season), thus suggesting secondary dormancy. This dormancy appeared to be caused by drastic decreases in GAs, rather than increases in ABA. Levels of GA(4) decreased to non-detectable values during dormancy in both species. Furthermore, zeatin levels decreased in X. bialata but not in X.peregrina during this period. Both species accumulated γ-tocopherol as the major vitamin E form, and levels of this antioxidant remained constant or even increased during seed burial; however, X. bialata seeds showed a significant decrease in α-tocopherol during seed burial and dormancy. It is concluded that in X. peregrina and X. bialata, (i) burial causes significant changes in the phytohormone levels of seeds; (ii) secondary dormancy is induced in seeds; (iii) a GA(4) decrease, rather than an ABA increase, seems to be involved in the induction of secondary dormancy; and (iv) reductions in α-tocopherol in buried seeds are not necessarily indicative of reduced germination capacity.

Zooplankton Dynamics in a Eutrophic Urban Reservoir: Four Scenarios over a Hydrological Cycle

Normal 0 21 false false false PT-BR X-NONE X-NONE The Ibirité reservoir, built in the 1960's in order to attend the Petrobras water demand, receives untreated wastewater, which results in a process of eutrophication, with periodic cyanobacterial blooms. The present study describes the zooplankton community of the Ibirité reservoir in terms of richness, composition and abundance throughout a complete hydrological cycle (Oct/2007 to Oct/2008), and considering some environmental variables. Four scenarios, with different environmental conditions that reflected in the zooplankton community structure were identified and described with the aid of analysis ordination (DCA and CCA) and variance: Scenario 0 -characterized by the onset of the rainy season (summer) (Oct/2007 and 2008), a period of high temperatures, high relative water column stability and apex of cyanobacterial blooms. In this scenario, the zooplankton was dominated by rotifer Brachionus calyciflorus .-Scenario 1 (Dec/2007, Feb and Apr/2008) -the rainy season apex and collapse of the cyanobacterial bloom by dilution. A reduction in the abundance of rotifers and nauplii (microzooplankton) was recorded in this period as a consequence of dilution and flushing these organisms through the spillway. -Scenario 2 (Jun/2008) -refers to the dry season, during which the reservoir had a low stability of the water column and no cyanobacterial bloom. In this period we registered the highest values of species richness and abundance, mainly rotifers and cladocerans. This can be explained by an hydrodynamic instability favoring r-strategists (e.g. rotifers) and reduction of predation pressure by vertebrates as consequence of fish mortality has occurred during this period. -Scenario 3 (Aug/2008), which represented the transition between the dry (winter) and rainy (summer) seasons, found the reservoir partially stratified, with the onset of algal bloom. In this period, the presence of the invasive rotifer Kellicottia bostoniensis was recorded for the first time in Ibirité reservoir.

A Spatiotemporal Analysis of Historical Droughts in Korea

AbstractThe climatological characteristics of drought in South Korea were investigated using daily precipitation data for 1777–2008. The effective drought index was used to quantify the drought intensity. As a result, five characteristics were discovered. First, South Korea can be divided into four drought subregions (the central, southern, and east coastal regions and Jeju Island) using hierarchical cluster analysis. Second, a map for long-term drought conditions in the four subregions is created that allows identification of the spatiotemporal distribution of droughts for the 231 yr at a glance. Third, droughts in South Korea have time scales that depend on the onset season. Spring (March–May) droughts tend to be short (≤200 days) because the summer (June–September) rainy season follows. Summer droughts tend to be long (&gt;200 days) because the dry season (October–February) follows. In the dry season, droughts tend to be sustained or become severe rather than being initiated or relieved. Fourth, 5-, 14-, 34-, and 115-yr drought cycles were identified by spectral analysis. The 5-yr cycle was dominant in all of the regions, the 14-yr cycle was observed over the southern and east coastal regions, and the 34-yr cycle was observed over the central region. Fifth, the most extreme drought occurred in 1897–1903 (return period: 233 yr) and was associated with the 115-yr drought cycle. After this drought, severe droughts (return period of &gt;10 yr) occurred in 1927–30, 1938–40, 1942–45, 1951–52, 1967–69, and 1994–96; they were caused by the consecutive shortage of summer rainfall for two or more years.

Hydrometeor vertical characterization of precipitating clouds over the Mexico Basin

A climatological study of the precipitation events for a 6-year period over the Mexico Basin with satellite Tropical Rainfall Measuring Mission (TRMM) datasets is presented. Atmospheric parameters retrieved from TRMM products are compared with those observed with radiosonde and synoptic data for annual and seasonal periods. The results of the comparison among hydrometeor vertical profiles, atmospheric soundings and North American Regional Reanalysis (NARR) datasets indicate that there is good agreement for cloud-base and 0°C-isotherm height levels. Also, it is confirmed that the geographical location of the study area, along with its typical meteorological characteristics, allows for the development of convective clouds with warm bases and cold cloud tops, particularly during the rainy (summer and autumn) season. Another interesting result of this hydrometeor vertical profile climatology is an explanation for the small number of ice precipitation events from storms over the Mexico Basin, despite its high altitude and geographical characteristics.

Antimicrobial sensitivity pattern of gram positive CSF isolates in children with septic meningitis in a Tertiary Care Hospital

The present study was conducted with the objective to determineantimicrobial susceptibility of Gram positive CSF isolates in septic meningitis in a tertiary care hospital. CSF (3-5 ml) was collected from 638 admitted children clinically suspected of septic meningitis. Bacterial isolates were identified and microbial sensitivity was assessed by the Kirby-Bauer’s disk diffusion method. Of the samples tested 102 (15.99%) were culture positive of which 45 (44.12%) culture positives were found inchildren aged 1-12 years. M: F ratio was 1.62:1. Maximum incidence (51 cases) was in summer-rainy season and in institutional delivery (58 cases). Primary immunization did not protect against septic meningitis. The isolates in 66 (64.71%) cases were Gram positive of which 36 (54.55%) were Streptococcus spp., 24 (36.36%) Staphylococcus aureus and 6 (9.09%) cases coagulase negative Staphylococcus (CONS). Both Streptococci and coagulase negative Staphylococci were highly sensitive (100%) to Linezolid, Vancomycin and Piperacillin-Tazobactam. However, Staphylococcus aureus were 100% sensitive to Linezolid and Vancomycin but were only 87.5% sensitive to Piperacillin-Tazobactam combination. The Streptococcus species showed a high degree of resistance to Tetracyclin91.67%, Co-trimoxazole 88.89% and Penicillin 63.89%. Staphylococcus aureus showed resistance to the tune of 83.33% each to Tetracycline and Co-trimoxazxole and 79.17% with Penicillin. In case of coagulase negative Staphylococcus, Co-trimoxazole showed resistance in 83.33%, Penicillin in 66.67% and Tetracycline in 50% cases. In septic meningitis Gram positive isolates predominate. Therapy should be based on trends of bacterial sensitivity.

Production indices for dual purpose cattle in central Brazil

This study examined the effects of crossbreeding low genetic potential cows of Bos indicus origin characterized by Gyr crossed with Holstein-Friesian and Simmental bulls to produce animals in a low input dual purpose system. The farm is situated near Brasilia, in the savannah region of Brazil. The climate of the region is classified as Aw by Köppen. Data was available on 1580 calvings and completed lactations of cows with three genetic types: Gyr, Holstein-Friesian × Gyr and Simmental × Gyr. The bulls ran with the cows all year round and the diet comprised of pasture (mainly Brachiaria and Andropogon) during the summer (rainy season) and milled sugar cane with added urea during the winter (dry season). A mineral salt mixture was available ad libitum. Data was analysed using Statistical Analysis System. The results show that, under low input management conditions, the crossbred cows produce approximately twice the volume of milk per lactation, calve at a younger age and have a shorter open period, but there are no significant differences between crosses for growth rates of the calves or body condition of the cows. In this system, crossbred cows had production higher indices than zebu cattle. The best indices were found for cows calving in the rainy season (September to December) and thinner cows (with body condition 3-5 on a scale of 9).

Human and Environmental Factors Affecting Aedes aegypti Distribution in an Arid Urban Environment

Aedes aegypti has reappeared in urban communities in the southwestern U.S.A. in the 1990s after a 40-year absence. In 2003 and 2004, a systematic survey was conducted throughout metropolitan Tucson, AZ, to identify human and environmental factors associated with Ae. aegypti distribution within an arid urban area. Aedes aegypti presence and abundance were measured monthly using the Centers for Disease Control and Prevention enhanced oviposition traps at sampling sites established in a grid at 3- to 4-km intervals across the city. Sampling occurred in the summer rainy season (July through September), the peak of mosquito activity in the region. Multiple regression analyses were conducted to determine relationships between mosquito density and factors that could influence mosquito distribution. House age was the only factor that showed a consistent significant association with Ae. aegypti abundance in both years: older houses had more mosquito eggs. This is the 1st study of Ae. aegypti distribution at a local level to identify house age as an explanatory factor independent of other human demographic factors. Further research into the reasons why mosquitoes were more abundant around older homes may help inform and refine future vector surveillance and control efforts in the event of a dengue outbreak in the region.

Reclaimed wastewater: Impact on soil–plant system under tropical conditions

This study investigated the ionic speciation of reclaimed urban wastewater (RWW), and the impact of increasing RWW irrigation rates on soil properties and plant nutrition under field conditions. Most RWW elements (>66%) are readily available as NH 4 +, Ca 2+, Mg 2+, K +, SO 4 2−, Cl −, H 3BO 3, Mn 2+ and Zn 2+, but in imbalanced proportion for plant nutrition. Lead, Cd, Cr and Al in RWW are mostly bounded with DOM or OH −. .Irrigation with RWW decreased soil acidity, which is beneficial to the acidic tropical soil. Although RWW irrigation builds exchangeable Na + up, the excessive Na + was leached out of the soil profile after a rainy summer season (>400 mm). Benefits of the disposal of RWW to the soil under tropical conditions were discussed, however, the over irrigation with RWW (>100% of crop evapotranspiration) led to a nutritional imbalance, accumulating S and leading to a plant deficiency of P and K.

Uncertainties in simulating regional climate of Southern Africa: sensitivity to physical parameterizations using WRF

This study aims at quantifying seasonal biases of regional climate model outputs during southern African summer, against a dense in situ measurement network (daily rain-gauge and surface air temperature records, and 12 h UTC radiosondes), and uncertainties associated with some physical parameterizations. Using the non-hydrostatic Advanced Research Weather Forecast (WRF) laterally forced by ERA40 reanalysis, twenty-seven experiments configured with three schemes of cumulus (CU), planetary boundary layer (PBL) and microphysics (MP), are performed at 35 km horizontal resolution during the core of a summer rainy season (December 1993 to February 1994 season) representative of the South African rainfall climatology. WRF simulates accurately seasonal large-scale rainfall patterns, as well as seasonal gradients of South African rainfall and 2-m temperature, and seasonal vertical profiles of the air temperature and humidity. However seasonal biases fluctuate strongly from an experiment to another, denoting considerable uncertainties generated by the physical package. Rainfall amounts are the most sensitive parameter to the tested schemes. Their geography, intensity, and intraseasonal characteristics are predominantly sensitive to CU schemes, and much less to PBL and MP schemes. Some CU-PBL combinations produce additive effects, which can dramatically either reduce or increase biases. Satisfactory configurations are found for South African climate, which would not have been possible without testing numerous physical parameterizations.

Comportamento agronômico de bananeira 'Prata-anã' em função do tipo de muda

Foi realizado um experimento de campo com bananeira 'Prata-anã', visando a avaliar o comportamento agronômico de plantas estabelecidas a partir de três tipos de mudas: convencional, micropropagadas em meio sólido e em meio líquido. A área experimental foi instalada no município de Cristais Paulista-SP (20º23'S; 47º30'W), cujo clima é caracterizado por verão chuvoso e inverno seco. Avaliaram-se o crescimento e a fenologia por meio de medidas periódicas de comprimento e diâmetro do pseudocaule das plantas até a emissão da inflorescência. A incidência de doenças (CMV e mal-do-panamá) foi estimada visualmente em função da apresentação de sintomas característicos pelas plantas. As plantas originadas de mudas micropropagadas apresentaram crescimento e desenvolvimento iniciais mais vigorosos, maior precocidade e cachos mais leves do que aquelas estabelecidas com mudas convencionais. Não foram observadas diferenças significativas em relação à incidência de doenças e ao tamanho dos frutos produzidos, em função dos tipos de mudas.

Ganhos de eficiência fertilizante em bananeira sob irrigação e fertirrigação

O aumento da eficiência fertilizante tem sido cada vez mais almejado nas boas práticas de manejo da adubação de culturas, não somente buscando reduzir custos de produção, mas também reduzir possíveis impactos ambientais. Com o objetivo de avaliar a eficiência dos fertilizantes nitrogenados e potássicos no cultivo da bananeira, foram realizados dois experimentos de campo com a cultivar 'Nanicão' (Musa AAA, subgrupo Cavendish), no Planalto do Estado de São Paulo, durante quatro ciclos de produção. Esta região caracteriza-se por estação chuvosa no verão e seca no inverno. No primeiro experimento, avaliou-se a eficiência da aplicação das doses de N: 0; 200; 400 e 800 kg ha-1 e de K: 0; 300; 600 e 900 kg ha-1 de K2O, em sistema de cultivo irrigado, comparado ao de sequeiro. No segundo experimento, estudou-se a eficiência da adubação com N e K aplicada por fertirrigação e de modo convencional via solo. Nos dois experimentos, a irrigação e a fertirrigação foram feitas por microaspersão, empregando-se como fontes de N e de K nitrato de amônio e cloreto de potássio, respectivamente. A eficiência dos fertilizantes foi estimada pela relação entre a massa dos frutos produzidos por unidade de nutriente aplicado. Para a média das doses empregadas e dos ciclos de produção, observou-se que a irrigação incrementou a eficiência da adubação em relação ao sequeiro, em aproximadamente 36 % e 32 %, respectivamente, para nitrogênio e potássio. A aplicação de nitrogênio e potássio via fertirrigação promoveu aumento de 36 % na eficiência fertilizante em relação à adubação sólida convencional, via solo. Incrementos na eficiência dos fertilizantes decorrentes da irrigação e da fertirrigação possibilitaram diminuir os gastos com o uso destes insumos.