Common bean is usually cropped under rainfed conditions and in soils with low pH and water retention, in the sub-humid and semiarid regions of Brazil. To improve soil conditions, smallholder farmers commonly use cattle manure. However, manure is available in limited amounts, insufficient to fertilize all cropping areas. Thus, other amendments, such as poultry manure (PM) and biochar (BC), have been proposed to increase soil water retention and pH. We evaluated the effects of BC (10, 20, and 40 t ha⁻¹; BC10, BC20, and BC40, respectively), PM (5 t ha⁻¹; PM), the combination of both amendments (BC10 + PM, BC20 + PM, and BC40 + PM) and an absolute control (Control), with no amendment, on soil physical, chemical, and biological properties, and on common bean water use efficiency (WUE) and yield. The treatments had no effects on total organic carbon, cation exchange capacity, microbial biomass carbon, soil physical properties, and evapotranspiration. Treatment combination BC (10 t ha⁻¹) + PM (5 t ha⁻¹) significantly improved phosphorus concentration, enzymatic activities, WUE, and bean yield in this one-year experiment and it can be a viable management practice for smallholder farmers in the Brazilian sub-humid region. However, further investigations are required to study the long-term field effects of the best performing soil amendments.

Biochar is a product rich in carbon, which improve the soil attributes and crop yield. In the Brazilian tropical dry region, common bean is cultivated under rainfed, in poor, acidic, and with low water retention soils. This work aims to evaluate the effect of biochar on soil physical and chemical attributes, on evapotranspiration (ET), water use efficiency (WUE), and on bean yield. The field experiment was conducted over four biochar rates (B0: no biochar; B10: biochar at 10 t ha⁻¹; B20: 20 t ha⁻¹ and B40: 40 t ha⁻¹), and three replications. Our analysis revealed that different rates of biochar do not affect the soil physical attributes due to a mismatch between soil texture and the particle size of biochar. Treatments with biochar promoted an increase in soil pH, P content, cation exchange capacity, reduced the Al+H content, which caused an increase in bean yield and consequently WUE. Our findings expand our knowledge about the effect of the biochar applied to the Acrisols on decreasing the soil acidity and to increase the yield and WUE, and add important information that can be suitable for development of strategy to mitigate problems caused by instability of rains and poor fertility soils.

A irrigação suplementar pode ser uma técnica promissora para o aumento da produção da palma forrageira, contudo, depende da evapotranspiração (ET). A irrigação e a ET estão estritamente relacionados com a produtividade das culturas (P), de modo que a relação entre P e ET resulta na eficiência no uso de água (EUA). Assim, objetivou-se avaliar P, ET e EUA em palma, sob irrigação suplementar. O experimento foi conduzido em campo, com palma submetida a irrigação por gotejamento com intervalos de reposição de água no solo de 7 (T7), 14 (T14) e 21 (T21) dias, mais o tratamento de sequeiro (T0), em blocos ao acaso, com 4 repetições. O crescimento da palma foi monitorado por meio da medição da largura (LC), do comprimento (CC), da área (AC), do índice de área (IAC) e da espessura dos cladódios (EC). Ao longo do ciclo da cultura também foram monitoradas as condições meteorológicas. A ET foi obtida como termo residual da equação do balanço hídrico. Os tratamentos não tiveram efeitos significativos nas variáveis biométricas e na produtividade da palma forrageira. A menor ET foi obtida no T0 (406,1 mm total e 1,7 mm d‑1), sendo que o T7 apresentou a maior ET (664,4 mm total e 2,8 mm d-1). A maior EUA (392,8 kg MF ha-1 mm-1) foi obtida no tratamento sob sequeiro (T0). Com base na produtividade e na EUA da palma forrageira, recomenda-se, para as condições do município de Garanhuns, que o cultivo da mesma seja realizado sob condições de sequeiro.Effect of the Supplemental Irrigation on Yield and Water Use Efficiency of Cactus Pear A B S T R A C TThe supplementary irrigation may be a promising technique to increase forage cactus yield, however, it depends of evapotranspiration (ET). Irrigation and ET are closely related to crop yields (P), so the relationships between P and ET result in water use efficiency (WUE). Thus, the objective was to evaluate P, ET and WUE in cactus pear, under supplementary irrigation. The experiment was conducted under field conditions with cactus pear submitted to drip irrigation with soil water replacement intervals of 7 (T7), 14 (T14) and 21 (T21) days, plus the rainfed treatment (T0), in blocks with 4 replicates. Cactus pear growth, by the measurements of width (WC), length (LC), area (CA), area index (CAI) and thickness of cladodes (CD), was monitored. Meteorological conditions along the cactus pear cycle were monitored. The ET was quantified by the soil water balance method. The treatments had no effects on the biometric variables and yield of cactus pear. ET was lower in T0 (406.1 mm total and 1.7 mm day-1), with T7 showing the highest values of ET (664.4 mm total and 2.8 mm day-1). It was observed that the largest WUE (392.8 kg MF ha-1 mm-1) was in the rainfed treatment (T0). On the basis of the yield and WUE of the cactus pear, it is recommended, for the conditions of the municipality of Garanhuns that the cultivation of the same be carried out under conditions of rainfed.Key words: Soil moisture; evapotranspiration; water balance.

Ecossistemas de regiões semiáridas, como a Caatinga, estão sendo afetados pelas mudanças climáticas globais, causando alterações na evapotranspiração (ET) e nos fluxos de CO2. Desse modo, o trabalho objetivou quantificar os fluxos de CO2 e ET, com o intuito de observar se a Caatinga atua como fonte ou como sumidouro de CO2. As medidas foram realizadas numa área de Caatinga, durante um período de 13 meses, no município de São João/PE, utilizando-se a metodologia da correlação dos turbilhões, com um analisador de CO2 e H2O e um anemômetro sônico tridimensional. Além disso, foi medida a umidade do solo nas profundidades de 10 a 50 cm. A ET variou de 0,4 a 4,7 mm d-1, com uma média de 2,33 mm d-1 e total de 933 mm. A ET também seguiu as variações da precipitação pluvial, com os valores mais elevados no período úmido e os menores, no período seco, possivelmente devido à baixa capacidade de retenção de água no solo. A variação do fluxo de CO2 na Caatinga indicou que a vegetação atuou ora como fonte e ora como sumidouro de carbono, com valores variando entre -4,89 e 6,87 μmol m-2 s-1. Entretanto, a Caatinga atuou, de maneira geral, como sumidouro de CO2, sequestrando, em média, 4,44 t C ha-1 ano-1. Desse modo, pode-se concluir que, nas condições edafoclimáticas do agreste pernambucano, a Caatinga atua sequestrando CO2 atmosférico, reforçando ainda mais a necessidade de preservação desse ecossistema.Palavras-chave: Caatinga; evapotranspiração; carbono; umidade do solo. Land Use Changes and Effects on the Water Balance Components in Agreste Pernambucano A B S T R A C TEcosystems in semi-arid regions, such as the Caatinga, are being affected by climate change, causing changes in evapotranspiration (ET) and CO2 fluxes. Thus, the work aimed to quantify the CO2 fluxes and ET, in order to observe whether the Caatinga acts as a source or a sink of CO2. The measurements were carried out in an area of Caatinga, during a period of 13 months, in the municipality of São João/PE, using the methodology of eddy covariance, with a CO2 and H2O analyzer and a three-dimensional sonic anemometer. In addition, soil moisture was measured at depths of 10 to 50 cm. The ET ranged from 0.4 to 4.7 mm d-1, with a mean of 2.3 mm d-1 and a total of 933 mm. The ET also followed the variations in rainfall, with the highest values in the wet season and the lowest in the dry season, possibly due to the low water retention capacity in the soil. The variation of the CO2 flux in the Caatinga indicated that the vegetation acted either as a source or as a sink of carbon, with values varying between -4.89 and 6.87 μmol m-2 s-1, being that the Caatinga acted, in general, as a CO2 sink, sequestering, on average, 4.44 t C ha-1 year-1. Thus, it can be concluded that, in the edaphoclimatic conditions of the Agreste of Pernambuco, the Caatinga acts by sequestering atmospheric CO2, further reinforcing the need to preserve this ecosystem.Key words: Caatinga; evapotranspiration; carbon; soil water content.

This study aimed to conduct a meta-analysis (MA) of systematic review data on poultry litter biochar (PLB) to answer the following questions: (i) What are the major studies regarding this worldwide? (ii) Which soil chemical attributes are the most affected? and (iii) Does PLB improve soil quality and crop productivity? MA revealed that the application of PLB significantly changed several key soil attributes, including pH, cation exchange capacity (CEC), and nitrogen, carbon, potassium, calcium, magnesium, and aluminum content. Specifically, MA showed that PLB decreased Al³⁺ in the soil by 71% while increasing pH, N, C, and CEC by 16, 20, 36, and 82%, respectively. This significant increase in CEC was associated with the addition of Ca²⁺, Mg²⁺, and K⁺ cations by 43, 202, and 636%, respectively. It was verified that PLB serves a dual function: it corrects soil acidity and pH while also enhancing the content of key nutrients, such as C and N. This study broadens the understanding of the potential of reusing poultry litter in biochar production, offering valuable data for developing strategies to improve both soil health and fertility.

Elephant grass [Cenchrus purpureus (Schum.) Morrone] is a tropical forage grass widely used in ruminant feeding in tropical and subtropical areas, mainly in cut-and-carry systems due to is high potential for herbage accumulation. However, most common genotypes (tall genotypes) generally show an early stem elongation, which contributes to a rapid decline in the forage nutritive value. Dwarf elephant grass types usually present less stem elongation and may be considered an option for the production of high nutritive value forage in cut-and-carry systems. The aims of this study were to evaluate and explain variations in herbage characteristics and kinetics of in vitro gas production of irrigated elephant grass genotypes (two tall-types – Elephant B and IRI-381 – and two dwarf-types genotypes – Mott and Taiwan A-146 2.37) under two harvest frequencies (60 and 90 days) in the dry and rainy seasons of two years. Herbage characteristics varied among genotypes, harvest frequency and seasons. Dwarf genotypes showed better in vitro fermentation parameters with the advancement of maturity compared to the tall size genotypes. Harvesting tall genotypes at a higher frequency (60-day) contributed to improving the fermentation, while dwarf elephant grass maintained greater fermentation when less frequent harvests were adopted (90-day).