A soil scientist is evaluating nitrogen retention in three soil types: sandy, loam, and clay. Sandy soil retains 12% of applied nitrogen, loam retains 25%, and clay retains 35%. She applies 80 kg of nitrogen per hectare to a 0.6-hectare sandy plot, 0.4-hectare loam, and 0.5-hectare clay. How many total kilograms of nitrogen are retained across all plots?

["Title: Soil Nitrogen Retention: Comparing Retention Rates Across Sandy, Loam, and Clay Soils", "Understanding how different soil types retain nitrogen is crucial for optimizing fertilizer use and enhancing sustainable agricultural practices. A recent evaluation by a soil scientist reveals significant differences in nitrogen retention among sandy, loam, and clay soils, offering valuable insights for precision farming.", "### Nitrogen Retention Across Soil Types", "Nitrogen retention varies significantly based on soil texture. In this study:", "- Sandy soil retains just 12% of applied nitrogen.\n- Loam soil retains 25%, offering moderate nitrogen retention.\n- Clay soil demonstrates the strongest retention at 35%.", "These percentages reflect how soil structure influences nitrogen availability—sandy soils drain quickly and bind nitrogen weakly, while clay soils hold nutrients tightly due to their fine particles and high organic matter content.", "### Application Rates and Plot Sizes", "The scientist applied 80 kg of nitrogen per hectare across three different plots:", "1. Sandy soil plot: 0.6 hectares\n2. Loam soil plot: 0.4 hectares\n3. Clay soil plot: 0.5 hectares", "We calculate the total nitrogen applied per soil type first, then determine how much is retained based on retention rates.", "---", "### Step-by-Step Calculation", "#### 1. Calculate nitrogen applied per soil type", "- Sandy:\n ( 80 , \ ext{kg/ha} \ imes 0.6 , \ ext{ha} = 48 , \ ext{kg} )", "- Loam:\n ( 80 , \ ext{kg/ha} \ imes 0.4 , \ ext{ha} = 32 , \ ext{kg} )", "- Clay:\n ( 80 , \ ext{kg/ha} \ imes 0.5 , \ ext{ha} = 40 , \ ext{kg} )", "#### 2. Calculate nitrogen retained per soil type", "- Sandy:\n ( 48 , \ ext{kg} \ imes 0.12 = 5.76 , \ ext{kg} )", "- Loam:\n ( 32 , \ ext{kg} \ imes 0.25 = 8.00 , \ ext{kg} )", "- Clay:\n ( 40 , \ ext{kg} \ imes 0.35 = 14.00 , \ ext{kg} )", "#### 3. Total nitrogen retained across all plots", "[\n5.76, \ ext{kg} + 8.00, \ ext{kg} + 14.00, \ ext{kg} = 27.76, \ ext{kg}\n]", "---", "### Conclusion", "The evaluation shows that despite receiving nearly identical nitrogen applications—48 kg in sandy soil, 32 kg in loam, and 40 kg in clay—the total retained nitrogen is significantly higher in clay soils (14 kg) compared to sandy (5.76 kg) and loam (8.00 kg). This emphasizes the critical role soil texture plays in nutrient management and underscores the benefits of tailored fertilizer strategies based on soil type to enhance crop productivity and reduce environmental losses.", "Key takeaways:", "- Sandy soils retain only ~12% of applied nitrogen, limiting efficiency.\n- Loam soils show moderate retention (25%), often optimal for balanced nutrient availability.\n- Clay soils retain up to 35%, making them highly effective at holding nitrogen but also requiring careful management to prevent leaching or runoff.", "Agriculture professionals and farmers can use this data to optimize nitrogen fertilizer rates and application timing across different soil types—improving sustainability and efficiency in crop nutrient use.", "---", "Keywords: nitrogen retention, soil science, sandy soil, loam soil, clay soil, fertilizer efficiency, nitrogen application, soil texture, agricultural science, sustainable farming."]