Laíze Aparecida Ferreira Vilela

Maize–tropical grass intercropping has been adopted during the dry season as a strategy for soil cover; however, a knowledge gap remains regarding adequate nitrogen (N) supply and the efficiency of this system in degraded pasture areas. The objective of this study was to evaluate dry biomass, grain yield, and macronutrient concentrations in maize–tropical grass intercropping as a function of N rates applied as side-dressing in the dry season. The experimental design consisted of a randomized complete block design in a split-plot arrangement with four replications. Main plots comprised maize monoculture, maize intercropped with Urochloa ruziziensis (Congo grass), and maize intercropped with Megathyrsus maximus cv. Aruana (Aruana Guinea grass). Subplots consisted of N rates (0, 50, 100, and 150 kg ha⁻¹). Maize–Aruana intercropping showed a positive linear response to N rates for grain yield; specifically, the nitrogen rate of 150 kg ha⁻¹ resulted in a 71.71% increase in grain yield compared to the lack of nitrogen supply. Conversely, maize monoculture showed a negative linear response, where the highest N rate (150 kg ha⁻¹) resulted in a 68.83% reduction in grain yield compared to the lack of nitrogen supply. Despite yield potential being capped by seasonal water deficits and frost events, the intercropping systems maintained essential growth dynamics. Aruana grass provided a protective effect for maize development under stress. The findings demonstrate that N side-dressing in the maize–Aruana intercropping system in a minimum of 71.83 kg ha⁻¹ is an adequate strategy to enhance grain yield and biomass production.

The development of an efficient agricultural system depends on the correct choice of crops and the management of nutrient supply and distribution within the system. This study aimed to determine how nitrogen (N) rates applied to rows of maize and tropical grass during the autumn–winter season (previous crop) influence subsequent intercropped plants. Treatments were arranged in a randomized complete block design with a split-plot scheme and four replications. The main plots comprised three cropping systems: soybean monoculture, soybean intercropped with Aruana Guinea grass (Megathyrsus maximus cv. Aruana), and soybean intercropped with Congo grass (Urochloa ruziziensis cv. Comum). The subplots consisted of four N rates (0, 50, 100, and 150 kg ha⁻¹) applied to the rows of maize and tropical grass during the previous crop. Macronutrient accumulation and efficiency indices were determined for intercropped plants. Aruana Guinea grass increased the accumulation of N, phosphorus (P), potassium (K), and sulphur (S) in the soybean crop. N applied to the previous crop negatively affected the accumulation of P, K, and S in soybean monoculture. The maximum physiological efficiency of soybean was related to N supply. The efficiency indices for Aruana Guinea grass highlighted its ability to recover residual N applied to the previous crop.

In Brazil, grain crops in no-till soybean–maize succession have reduced biodiversity and carbon input into soil. Intercropping is a promising approach to address these problems. This study aimed to evaluate the microbiological quality of soil in conventional and intercropping systems in soybean–maize succession, depending on tropical grass and nitrogen fertilizer uses. The treatments were arranged in a randomized complete block design and a split plot scheme, with four replications. The main plots consisted of the following cropping systems: soybean monoculture–maize monoculture; soybean intercropped with Aruana Guinea grass (Megathyrsus maximum cv. Aruana)–maize intercropped with Aruana Guinea grass; and soybean intercropped with Congo grass (Urochloa ruziziensis cv. Comun)–maize intercropped with Congo grass. The subplots consisted of nitrogen rates (0, 50, 100, and 150 kg ha⁻¹) applied as side-dressing in rows of maize and tropical grass in the autumn–winter season. Our results showed that maize or soybean intercropped with tropical grasses and adequate nitrogen rates favored the entry of microbial carbon and nitrogen, stimulated enzymatic activity, and reduced C-CO₂ loss. However, the excess nitrogen supply can nullify the benefits of the intercropping systems. We concluded that the intercropping systems can improve soil microbiological quality in a short time with adequate nitrogen supply.

Esta pesquisa diagnosticou o conhecimento empírico dos agricultores do município de Campina do Monte Alegre - SP sobre a classificação e uso agrícola dos solos e o correlacionou ao Sistema Brasileiro de Classificação de Solos (SiBCS) e à classificação da capacidade de uso das terras. A pesquisa etnopedológica englobou 20 áreas agrícolas e 17 agricultores foram entrevistados. A metodologia consistiu nas seguintes etapas: 1) elaboração do roteiro semiestruturado e realização das entrevistas; 2) amostragem e descrição morfológica dos solos; 3) sistematização e análise de conteúdo das entrevistas, com auxílio do software ATLAS.ti e 4) elaboração do mapa pedológico. Os principais atributos etnopedológicos utilizados pelos agricultores foram: cor, textura, consistência, fertilidade, acidez, teor de matéria orgânica, pedregosidade e plantas indicadoras. As classes etnopedológicas identificadas foram: “Terra Vermelha ou de Campo” (Latossolos Vermelhos, Argissolos Vermelhos e Argissolos Vermelho-Amarelos); “Terra Roxa” (Nitossolos Vermelhos e Latossolos Vermelhos); “Terra Branca” (Plintossolos Argilúvicos; Gleissolos Melânicos e Gleissolos Háplicos) e “Terra de Areia” (Argissolos Bruno-Acinzentados e Argissolos Vermelho-Amarelos). As classes etnopedológicas “Terra Vermelha ou de Campo” e “Terra Roxa” predominaram nas áreas agrícolas visitadas e, conforme o sistema de capacidade de uso das terras, foram classificadas como IIe,s e IIIe,s.

Soil structure has major influence on ecosystem sustainability and plant growth. Arbuscular mycorrhizal fungi (AMF) are an important functional group of soil microbiota, acting in the process of aggregation, especially in agroecosystems and related to the production and plant diversity. AMF are widely distributed in tropical agroecosystems and are extremely important for development of many agricultural crops. The present study evaluated the effect of inoculation with Glomus macrocarpum in different crop sequences on plant growth, microbial activity and aggregation of a Cerrado Oxisol. The study was conducted in a completely randomized design in a4 x 4 factorial scheme. Treatments consisted of four conditions of elimination and/or introduction of AMF (NS-NI: non-sterilized and non-inoculated; NS-I: non-sterilized and inoculated; S-NI: sterilized and non-inoculated; andS-I: sterilized and inoculated) and four crop sequences (Panicum maximum/Panicum maximum, Brachiaria ruziziensis/ soybean, sorghum/soybean and Stylosanthes spp./soybean). Inoculation favored growth of Stylosanthes spp. by increasing plant growth in up to 91% when inoculated. None of the grasses benefited from G. macrocarpum introduction. We observed that G. macrocarpum inoculation associated with indigenous AMF increased microbial biomass, phosphatase activity, mean geometric diameter and mean weighted diameter. The results indicated the beneficial effects of inoculation, which reflected in soil structure improvement and, hence, to agroecosystems sustainability.