Development Of Cover Crops Research Articles

Monitoring Cover Crop Biomass in Southern Brazil Using Combined PlanetScope and Sentinel-1 SAR Data

Precision agriculture integrates multiple sensors and data types to support farmers with informed decision-making tools throughout crop cycles. This study evaluated Aboveground Biomass (AGB) estimates of Rye using attributes derived from PlanetScope (PS) optical, Sentinel-1 Synthetic Aperture Radar (SAR), and hybrid (optical plus SAR) datasets. Optical attributes encompassed surface reflectance from PS’s blue, green, red, and near-infrared (NIR) bands, alongside the Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI). Sentinel-1 SAR attributes included the C-band Synthetic Aperture Radar Ground Range Detected, VV and HH polarizations, and both Ratio and Polarization (Pol) indices. Ground reference AGB data for Rye (Secale cereal L.) were collected from 50 samples and four dates at a farm located in southern Brazil, aligning with image acquisition dates. Multiple linear regression models were trained and validated. AGB was estimated based on individual (optical PS or Sentinel-1 SAR) and combined datasets (optical plus SAR). This process was repeated 100 times, and variable importance was extracted. Results revealed improved Rye AGB estimates with integrated optical and SAR data. Optical vegetation indices displayed higher correlation coefficients (r) for AGB estimation (r = +0.67 for both EVI and NDVI) compared to SAR attributes like VV, Ratio, and polarization (r ranging from −0.52 to −0.58). However, the hybrid regression model enhanced AGB estimation (R2 = 0.62, p < 0.01), reducing RMSE to 579 kg·ha−1. Using only optical or SAR data yielded R2 values of 0.51 and 0.42, respectively (p < 0.01). In the hybrid model, the most important predictors were VV, NIR, blue, and EVI. Spatial distribution analysis of predicted Rye AGB unveiled agricultural zones associated with varying biomass throughout the cover crop development. Our findings underscored the complementarity of optical with SAR data to enhance AGB estimates of cover crops, offering valuable insights for agricultural zoning to support soil and cash crop management.

Short communication. The role of rabbit density and the diversity of weeds in the development of cover crops in olive groves

Cover crops are an effective means to reduce soil erosion and to provide food and shelter for wildlife. However, in areas of intensive farming, which are characterised by the scarcity of weed communities, wild herbivores may focus their grazing on cover crops, which could make their implementation difficult. In this work, we test whether rabbit grazing can prevent the growth of herbaceous cover crops in olive groves in Southern Spain in addition to assessing the role of rabbit abundance and diversity of weeds in the development of cover crops. This question has been addressed by sowing Bromus rubens between the rows of five olive groves in Cordoba province (Spain). We then monitored the surface covered by B. rubens, along with both diversity of weed communities and rabbit abundance. Two rabbit exclusion areas were also placed in each olive grove in order to assess the impact of rabbits on the development of cover crops. Our results showed that the surface occupied by B. rubens was considerably higher in the rabbit exclusion areas (mean 56.8 ± 5.65 %) than in those areas in which they could feed (mean 35.6 ± 4.32 %). The coverage occupied by cover crops was higher in areas with lower rabbit density, although this relationship was modulated by the weed diversity index, since in areas with the same rabbit abundance the coverage was higher in those with a richer weed community. These findings suggest that high rabbit abundances can prevent the development of herbaceous cover crops in olive groves, particularly in areas in which alternative food resources (measured as weed diversity) are scarce.

English

The objective was to evaluate the effect of intervals of irrigation frequency (water deficit) in the development of cover crops. The experiment was conducted in a greenhouse at the experimental campus of the Federal University of Piauí (UFPI) in Bom Jesus-PI in the period between June to August 2011, on soil classified as Typic Dystrophic - Lad. The experimental design was randomized blocks in factorial scheme 5 x 4, with factors consisting of 5 cover crops (Brachiaria brizantha cv. Piata; Mucuna aterrima; Pennisetum glaucum cv. ADR-500; P. glaucum cv. ADR 8010; Brachiaria brizantha cv. Marandu), and 4 intervals of irrigation frequency (2, 4, 6 and 8 days), with 4 replications. Cover crops were significantly affected in their development, with reductions in biomass above 50% when subjected to the interval of irrigation frequency to 8 days. The P. glaucum cv. ADR-500 has potential to overcome the water deficit conditions during the off season in the Cerrado of Piauí.   Key words: Brachiaria, Pennisetum glaucum cv. ADR-500, no-tillage.

Crescimento de milheto e guandu, desempenho de plantas cítricas e propriedades físicas do solo escarificado em um pomar

Escarificação do solo e plantas de cobertura em pomares podem ser utilizados para melhorar as condições físicas do solo. Este trabalho teve como objetivo avaliar a influência da escarificação no crescimento de adubos verdes, no desempenho das árvores e em propriedades físicas de um Latossolo Vermelho distroférrico, num pomar cítrico com histórico de compactação. Foi realizada uma escarificação à profundidade de 0,30 m, seguida por três tipos de plantas de cobertura: vegetação espontânea, guandu (Cajanus cajan) e milheto (Pennisetum americanum). O delineamento experimental utilizado foi o inteiramente aleatorizado, num fatorial 2 x 3 (escarificado e não-escarificado e três plantas de cobertura do solo). Para as coberturas do solo, foi avaliada a fitomassa da parte aérea e abertas trincheiras para avaliação do crescimento das raízes. As plantas cítricas foram avaliadas com relação a seu crescimento e produção. Os atributos físicos do solo foram determinados em três locais (copa, rodado e entrelinha) e quatro profundidades (0-0,1; 0,1-0,2; 0,2-0,3; e 0,3-0,4 m). A fitomassa da parte aérea do guandu e a do milheto aumentaram com a escarificação do solo. O crescimento do sistema radicular do milheto foi maior do que o do guandu no manejo escarificado e igual ao deste no manejo não-escarificado. O crescimento e a produção das plantas cítricas não foram influenciados pelos tratamentos. Houve aumento da macroporosidade do solo e redução da densidade e da resistência do solo à penetração com a escarificação do solo.

Impacts of site preparation techniques on runoff, soil and nitrogen losses during the establishment phase in hoop pine plantations of southeast Queensland

Summary Runoff, soil loss and associated nitrogen losses were measured over a 7-year period in recently re-established second rotation hoop pine (Araucaria cunninghamii) plantations and an undisturbed rainforest in southeast Queensland using small-scale catchment plots (ranging between 114 and 403 m2) with modified Gerlach troughs and tipping bucket technology. The effectiveness of prescription cover cropping systems in reducing hillslope erosion was assessed on general plantation areas ranging in slope from 10 to 25°, where the site had been prepared with burning regimes based on either push and burn or broadcast burn. A number of plots were maintained in a relatively vegetation-free state to assess the effectiveness of the cover crops. The runoff coefficient (runoff/rainfall) throughout the study period was low across all plots with a range between 0.5 and 4.2 % and it was apparent that only small areas of the catchment appeared to be contributing to runoff. Total soil loss over the 7-year study period was typically low (< 5.4 5.4 ha−1) for plots where good germination and development of cover crops had occurred. Plots with poor development of cover crops and those maintained relatively free of cover had greater total soil losses ranging between 16.2 and 87.8 t ha−1. Soil erodibility declined over time in all plots (rainforest excluded) with most soil loss occurring in the first 2 years of the rotation. Subsequently, soil loss was comparable to that found in the undisturbed rainforest. Annual losses of total nitrogen were generally low (< 11 kg ha−1 yr−1) and comparable to estimated annual inputs from the atmosphere and biological fixation.