Grass–Legume Forage Systems Effect on Phosphorus Removal from a Grassland Historically Irrigated with Reclaimed Wastewater

Abstract

The utilization of reclaimed wastewater is a suitable and sustainable approach to agriculture production in water-scarce regions. However, even though the wastewater is treated to reduce nutrient concentration such as phosphorus, the 10,600 to 14,006 m3 of water applied ha−1 year−1 on grass and alfalfa hay crops in Nevada can lead to soil phosphorus buildup over an extended period. This study evaluated the effectiveness of forage systems (FS) of monoculture grass, monoculture legume, and their mixtures on herbage accumulation, tissue phosphorus concentration, and quantity of phosphorus removed from a grassland under wastewater irrigation. The study was carried out at the Main Station Field laboratory in Reno, Nevada, USA. A total of 23 FS using tall fescue (Schedonorus arundinaceus (Schreb.) Dumort), alfalfa (Medicago sativa L.), red clover (Trifolium pratense L.) and white clover (Trifolium repens L.) in monocultures or grass–legume mixtures (25:75, 50:50, and 75:25) based on seeding rate were used. The response variables were herbage accumulation (HA), tissue phosphorus concentration, and phosphorus removal. Forage systems means were considered different P ≤ 0.05. Herbage accumulation, tissue phosphorus concentration, and phosphorus removal differed among FS and year. Herbage accumulation was similar for the grass monocultures (10.5 Mg ha−1; SE = 1.1) and the majority of the grass–legume mixtures (9.0 Mg ha−1; SE = 1.1) but both systems had greater HA than legumes monoculture (4.3 Mg ha−1; SE = 1.1). The legume monocultures of alfalfa and white clover had the greatest phosphorus concentrations (10.9 g kg−1 dry matter; SE = 0.44) among all FS. Total phosphorus removed was least among legume monocultures (34.0 kg P ha−1; SE = 6.2) in this study and generally similar for grass monocultures (67.4 kg P ha−1; SE = 6.2) and grass–legume mixtures of 75:25 (61.7 kg P ha−1; SE = 6.2). Based on the response variables, agronomic, and environmental considerations a grass–legume mixture that includes 75:25 or even a 50:50 seeding rate ratio will be suitable options for phosphorus removal from phosphorus enriched grasslands in semiarid ecosystems that utilized wastewater for irrigation.

Growth, Feed Intake And Conversion Ratio of Improved Goats Fed Brachiaria Grass And Napier Grass Mixed With or Without Leucaena Leaf Meal

“…However, its P was similar to that of Mulato II. The discrepancies of macro-elements between shrubs and grasses was expected because shrub legumes have higher uptake of these minerals (Pant et al, 2004;Mclennon et al, 2020). The high P in Mulato II in comparison to shrub legume has been reported in semi-arid and acidic soil prone areas of Rwanda (Mutimura and Everson, 2012).…”

The Occurrence of Legacy P Soils and Potential Mitigation Practices Using Activated Biochar

“…These practices create vegetative buffer strips along water bodies [ 33 , 34 ]. The implementation of these buffer strips also includes grass–legume forage systems [ 35 ] combined with the best nutrient management efforts such as the land application of P-sorbing materials; treating manure with aluminum sulfate; increasing plant P use efficiencies; and increasing the N:P ratio of manure [ 36 , 37 ]. However, these best management practices can be more effective on sediment-bound P in the runoff, but less effective in reducing dissolved P loss from sandy soils on the Delmarva Peninsula [ 38 , 39 ].…”

Evaluation of Perennial Grass-legume Cropping Systems for Year-round Supply of Fodder for Dairy Farms

“…It also increased dry matter production, crude protein yield and in vitro dry matter digestibility and decreased the fiber fractions. Mclennon et al (2020) reported that grass-legume mixture at 75:25 produced greater herbage than 25:75 grass-legume mixture and legume monoculture. Forage species mixtures (grass + legume) have showed increased total forage biomass production including nutrient content when compared to growing single species (Belanger et al 2014;Cardinale, et al 2007;Foster et al 2019).…”