Page 1. 101 Nutrient concentrations in runoff from different manure amended fields of the tropics under natural rainfall conditions1,2 Sandra L. Ortega-Achury3, Gustavo A. Martínez-Rodríguez4*, David Sotomayor-Ramírez5 and Miguel A.... more
Page 1. 101 Nutrient concentrations in runoff from different manure amended fields of the tropics under natural rainfall conditions1,2 Sandra L. Ortega-Achury3, Gustavo A. Martínez-Rodríguez4*, David Sotomayor-Ramírez5 and Miguel A. Muñoz-Muñoz5 J. Agric. Univ. ...
Assessing the dynamics of gaseous production in soils is of interest because they are important sources and sinks of greenhouse gases. Changes in soil air carbon dioxide (COâ) and nitrous oxide (NâO) concentrations were studied in a... more
Assessing the dynamics of gaseous production in soils is of interest because they are important sources and sinks of greenhouse gases. Changes in soil air carbon dioxide (COâ) and nitrous oxide (NâO) concentrations were studied in a Reading silt loam under prairie and cultivation. Concentrations were measured in situ over a 17-mo period to a depth of 3 m. Multilevel
Page 1. Carbon and Nitrogen Mineralization in Tallgrass Prairie and Agricultural Soil Profiles HA Ajwa, CW Rice,* and D. Sotomayor ... Although mi-HA Ajwa, USDA-ARS, Water Management Research Lab., Fresno, CA 93727; CW Rice, Dep. ...
Abstract Nutrient losses from agricultural fields are one of the principal causes of environmental degradation. Typical nitrogen (N) fertilizer consumption rates in vegetable production systems and horticultural crops, typically... more
Abstract Nutrient losses from agricultural fields are one of the principal causes of environmental degradation. Typical nitrogen (N) fertilizer consumption rates in vegetable production systems and horticultural crops, typically fluctuates between 112 to 253 kg N/ha. This can generate high residual soil N at harvest, and may increment N losses to the environment. The evaluation of N losses to the environment can be evaluated with simulation models such as the N-Index, that can be aid in the identification of N losses and evaluate the effect of best management practices. The N-Index is a simulation model that predicts N losses via surface, leaching, and atmospheric pathways. A field study was conducted to quantify the residual soil N and crop N uptake to validate the N-Index in vegetable production systems in the Lajas Valley in Puerto Rico. Field plots were established with vegetables such as onion (Allium cepa L.), pumpkin (Cucurbita Moschata D.), pepper (Capsicum annum), and tomat...
Coffee (Coffea arabica) planting in the interior mountainous region of Puerto Rico is usually performed on steep slopes after vegetation removal. The construction of individual terraces around the tree, such as the “Media Luna” planting... more
Coffee (Coffea arabica) planting in the interior mountainous region of Puerto Rico is usually performed on steep slopes after vegetation removal. The construction of individual terraces around the tree, such as the “Media Luna” planting method, prior to planting could reduce sediment and nutrient losses and could increase yields by improved on-site water and nutrient retention. Experiments were conducted to test the hypothesis that the “Media Luna” planting technique could reduce sediment, total phosphorus (TP), and total Kjeldahl nitrogen (TKN) in runoff during and after the establishment of a coffee plantation in Puerto Rico. The experiments were conducted on a commercial farm where the predominating soils were Múcara (Dystric Eutrudepts) in Phase 1, and Humatas (Typic Haplohumults) in Phase 2. In Phase 1 (recent plantings), sediment and nutrient runoff losses were similar in the conventional countour planting method and in the “Media Luna” treatments. Nutrient concentrations in r...
An experiment was conducted to test the hypothesis that grass filter strips are effective in reducing nutrient and sediment concentrations in run- off from grazed pasture amended with dairy manure sludge. The experiment was carried out... more
An experiment was conducted to test the hypothesis that grass filter strips are effective in reducing nutrient and sediment concentrations in run- off from grazed pasture amended with dairy manure sludge. The experiment was carried out under recommended practices in two fields of a dairy farm in San Sebastián municipality, Puerto Rico. Runoff generated following a precipitation event was diverted into runoff-collection devices placed at 0, 10, and 20 m within a grass filter barrier. Samples were analyzed for sus- pended solids (SS), total Kjeldahl nitrogen (TKN), dissolved phosphorus (DP), and total phosphorus (TP). Suspended solid concentrations in runoff entering the filter strips were minimal, which is indicative that SS losses are not numerically significant from pasture fields exhibiting high vegetative coverage. Elevated TP and TKN concentrations were observed in runoff events occurring within 10 days after manure application. This finding indi- cates that farmers must avoid s...
