Journal: Agrosystems, Geosciences & Environment

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Wiley

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ISSN

2639-6696

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2020 - 20253
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Publications 1 - 3 of 3
  • Paddy rice traits estimation under varying management strategies using UAV technology
    Item type: Journal Article
    Muhindo, Daniel; Lelei, Joyce J.; Munyahali, Wivine; et al. (2025)
    Agrosystems, Geosciences & Environment
    Timely crop monitoring and yield prediction are essential in guiding management decision making. The aim of the study was to estimate the agronomic traits of paddy rice (Oryza sativa L.) using unmanned aerial vehicle (UAV)-multispectral imaging. A randomized complete block design field experiment with a split-split plot arrangement was set up in the Ruzizi plain, Democratic Republic of Congo (DRC). Spectral imaging data were collected at rice tillering and panicle initiation stages. Predictive analysis of rice agronomic traits was performed using linear and decision tree-based machine learning techniques. Paddy rice trait predictions were critically sensitive to the timing of image acquisition but not largely affected by the model. The most accurate predictions were made at rice panicle initiation stage, with R2 values of 0.62, 0.65, and 0.75 for yield, aboveground biomass, and plant nitrogen (N) uptake, respectively. The visible atmospherically resistant index (VARI), modified chlorophyll absorption in reflective index, and ratio vegetation index, along with near infrared and green bands, played a critical role in predicting paddy rice N uptake and yield. The same spectral features associated with crop height and canopy data were essential for predicting paddy rice aboveground biomass. UAV-multispectral data were able to assess agricultural intensification strategies at field/landscape scale irrespective of soil types, watering regimes, and cultivars. Special consideration should be attributed to VARI, as it enables economical prediction of paddy rice traits. The UAV technologies are therefore reliable tools for monitoring rice production and can be applied in agricultural extension in the DRC.
  • Nitrogen and phosphorus uptake from isotope‐labeled fertilizers by sorghum and soil microorganisms
    Item type: Journal Article
    Traoré, Ouakoltio Y.A.; Kiba, Delwendé I.; Bünemann, Else K.; et al. (2020)
    Agrosystems, Geosciences & Environment
    On nutrient‐depleted Lixisols from Burkina Faso, nutrient acquisition by crops and soil microbes mainly relies on the limited amounts of mineral and organic fertilizers applied by small‐scale farmers. The objective of this study was to determine simultaneously the uptake of nitrogen (N) and phosphorus (P) contained in organic and mineral fertilizers by sorghum [Sorghum bicolor (L.) Moench ] and soil microbial biomass. Double 15N and 33P direct and indirect labeling techniques were applied in a pot experiment to determine the contributions of different fertilizers to sorghum N and P uptake during 52 d of growth. In parallel, soil respiration, available, and microbial N and P were tracked in an incubation experiment. Sorghum derived 83–90% of P from fertilizers. Nitrogen from cattle manure was poorly available, contributing only 20% of the N taken up by sorghum. Water‐soluble mineral fertilizers increased soil N and P availability, resulting in the highest total N and P uptake by sorghum from fertilizers and soil among all treatments. The application of cowpea [Vigna unguiculata (L.) Walp.] residues induced microbial N and P immobilization, reducing sorghum N and P uptake to the level of the non‐fertilized treatment. The use of double 15N and 33P labeling elucidated the impact of fertilizers on soil nutrient pools. The low plant N/P ratio suggested N limitation for sorghum in the manure treatment. Cowpea residues were inefficient for sorghum nutrition, but they increased soil microbial nutrient pools. This study gives insights on the potential effects of legume residues used as green manure to build soil fertility.
  • An isotope study on nitrogen and phosphorus use efficiency and movement in soil in a mimicked vermicompost-based organo-mineral fertilizer
    Item type: Journal Article
    Sitzmann, Tomas J.; Sica, Pietro; Zavattaro, Laura; et al. (2024)
    Agrosystems, Geosciences & Environment
    Vermicompost (VC), a stabilized organic material with high organic and humic carbon, and favorable aggregation properties, was tested as a fraction of organo-mineral fertilizers (OMFs), where organic and mineral fractions interact in hotspot areas with surrounding soil. Solutions containing 33P radioisotope and 15N-labeled mineral fertilizers were combined with VC at two ratios of organic carbon (Corg) to mineral nitrogen (N) and phosphorus (P) (OMF7.5C and OMF15C) to simulate OMF granules. Control treatments included unfertilized soil (N0P0), mineral fertilizer (MFNP), and sole VC at two rates (OF7.5C and OF15C). Nitrogen and P uptake by Italian ryegrass (Lolium multiflorum) were measured over in 8 weeks. Furthermore, MFNP, OMF7.5C, and OMF15C treatments were incubated for 10 days without plant to measure atom% 15N excess and 33P radioactivity, as indicators of N and P movement from two soil layers (surrounding fertilizer hotspot and below it). In the pot study, OMF15C caused 24% lower biomass and less nutrient recovery derived from fertilizer (N, 11% and P, 8.5%), compared to MFNP. In the incubation study, OMF15C exhibited +19% atom% 15N excess in the combined two soil layers, relative to MFNP, and +28% 33P radioactivity in the soil surrounding the hotspot, and −89% in the soil below it. We interpreted this as a reduction in nutrient availability of the combined VC + mineral fertilizers, due to lower P mobility in soil. The combination of VC with mineral fertilizers can reduce P movement in soil. A higher Corg:N:P ratio resulted in lower nutrient use efficiency in 2 months.
Publications 1 - 3 of 3