System for value-added export of manure nitrogen and phosphorus through turfgrass sod

System for value-added export of manure nitrogen and phosphorus through turfgrass sod

Summary

Dairy manure was applied on turfgrass to quantify P and N export in sod and runoff losses during production and after transplanting of sod. Percentages of applied P and N in sod harvests were similar among manure rates, but differed among turf species. The feasibility of exporting manure in sod was demonstrated through: 1.) Removal of large P and N amounts in sod harvests, 2.) similar runoff losses between manure and fertilizer sources of P during sod production, and 3.) similar runoff losses for transplanted sod produced with manure or fertilizer.

Objectives/Performance Targets

1. Expand and sustain the learning system of stakeholders during development and evaluation of an infrastructure for using and adding value to manure sources of N and P.

   Develop and evaluate an integrated dairy and turfgrass system that will use and minimize losses of manure sources of N and P during sod production, export, and transplanting.

   Analyze and evaluate the operational and economical feasibility of exporting manure sources of N and P from watersheds through turfgrass sod.

Accomplishments/Milestones

Learning system.
The learning system of stakeholders has been sustained through semi-annual meetings of the entire project team, workshops, and continuing partnerships among team participants in research, demonstrations, and development projects. In addition, the team contributed to planning of related research, including successful research proposals funded by the United States Geological Survey, USDA-CREES, and the Texas Advanced Technology Program.

Sod responses in replicated plots
Following the initial sod harvest of replicated plots of ‘Tifway’ bermudagrass, ‘609’ buffalograss, and ‘Reveille’ bluegrass on experiment station sites, manure and fertilizer applications were continued to evaluate sod regrowth and the minimum time required to produce and harvest sod. Application of supplemental N fertilizer with P rates of 100 and 200 kg P/ha in composted dairy manure achieved the most rapid growth rates of Tifway bermudagrass and Reveille Bluegrass sod. Tifway sod was produced in just 4 months at College Station, Tx and Reveille sod in 11 months at Stephenville, TX. The time required for a sod crop was comparable between sod produced with composted manure plus N fertilizer and with inorganic fertilizer sources of N, P, and K. Analysis of P and N removal in sod remains to be completed, but two Tifway sod harvests per calendar year could remove up to 300 kg of the P applied per ha as composted manure during sod production.

Sod responses in pilot-scale demonstrations.
Project collaborators have agreed to establish pilot-scale fields of ‘Tifway’ bermudagrass and ‘Reveille’ bluegrass on an experiment station site and on dairy and sod farms in north-central Texas. Tifway bermudagrass and Reveille bluegrass sods were established on Harold Pack’s dairy during 2000 and 2001. Three treatments were applied to two replications after seeding or sprigging of each species: 1.) Control or no nutrients added, 2.) 200 kg P/ha applied as composted manure, and 3.) 200 kg P/ha applied as composted manure plus two applications 50 kg N/ha. The Tifway sod was harvested on August 20, 2001 and Reveille sod was harvested on October 29, 2001. Nutrient amounts in vegetation and soil components of sod are currently being analyzed. After sod harvests, manure and fertilizer treatments were reapplied to sod plots.
Mark Quinn and Sam Peterson are collaborating in establishment of 8 ha of Zoysiagrass near Mark’s dairy feedyard. Zoysiagrass plugs were transplanted after application of stockpiled manure and installation of irrigation systems through which wastewater is applied. Sod will be sampled during harvest to quantify P and N removal in sod during summer, 2002.

Tifway bermudagrass will be plugged and established on two 1.2-ha fields on the TAMU research farm during Spring, 2002. Fields have been leveled, tilled, isolated by soil berms, and equipped with automated equipment for monitoring and sampling surface runoff. In addition, background concentrations of nutrients in groundwater wells within each field have been sampled and measured. One field will receive 200 kg P/ha as composted dairy manure and P fertilizer will be applied to raise extractable soil P to 100 kg P/ha on the other field after plugs have rooted. Nutrient removal in sod harvests and losses through runoff and leaching will be evaluated during 2002.

Replicated runoff plots.
In addition to measurements of bermudagrass (Cynodon dactylon var. Guymon) turf responses, volumes and P and N concentrations of surface runoff were monitored during evaluations of composted manure applications in turfgrass production. Manure rates that supplied 50 and 100 kg P/ha at the start of each of two monitoring periods were compared to P fertilizer rates of 25 and 50 kg/ha and an unfertilized control. Two applications totaling 100 kg N/ha were applied with the P fertilizer. Three replications of treatments were established on a Boonville fine-sandy-loam (fine, smectitic, thermic Ruptic-vertic Albaqualf) that was excavated to create an 8.5 percent slope. Compared to initial soil tests, nitrate concentrations decreased to 2 mg/kg and P concentrations increased after two manure and fertilizer applications and eight rain events over the two monitoring periods. The fertilizer sources of P and N produced 19 percent more dry weight and 21 percent larger N concentrations in grass clippings than manure sources. Runoff volumes did not differ between manure and fertilizer sources of P, but average volumes recorded for the unfertilized control were 22 percent greater than either source or rate of P during the second monitoring period. Dissolved P concentration (30 mg/L) in runoff was 5 times greater for fertilizer than for manure when rain occurred 3 d after P applications at the same rate. Similarly, total dissolved P losses in runoff above those of the control were 1.4 times greater for fertilizer than for manure when both were applied in two applications at equal P rates (100 kg P/ha/y). Under the relatively large P rates on a steep slope of turfgrass, P and N losses in runoff during eight natural rain events were no greater for composted manure than for fertilizer sources of P.

Nutrient losses in runoff from transplanted sod.
During Fall, 2000 and Spring, 2001, volumes and P and N concentrations of surface runoff were compared among replicated controls and treatments that received manure or fertilizer after a sod harvest or transplanted sod produced with manure or fertilizer. A randomized complete block design comprised three replications of seven treatments applied on an 8.5 percent slope (Table 1). Metal edging was inserted into soil on plot perimeters. Runoff of natural rain events was collected through H-flumes into 311-L tanks at the base of plots. Sod was removed from plots prior to treatments. Runoff was monitored during three periods after after various rates and sources of P were applied to bare soil of plots (Table 1). Tifway bermudagrass sod was transplanted or sprigs were planted prior to monitoring periods I or II (Table 1). Sod received 200 or 400 kg/ ha P as manure prior to harvest. Water depth in tanks was measured to compute runoff volume. Runoff samples (0.5 L) were removed while mixing tanks. Runoff samples were filtered through glass microfiber filters (pore size of 1.4 microns) and filtrate was analyzed by the Texas A&M Soil, Water, and Forage Testing Laboratory.

During monitoring period I, variation of N and P losses in runoff was
significant for treatments, rain events, and the interaction thereof (P=0.05). Runoff losses of N and P during the first rain event (7 d) after manure or fertilizer applications were larger than the second event. Runoff losses of N and P 7 d after surface application of manure or fertilizer were 2 to 3 times greater than losses from transplanted sod, control, and bare soil. Runoff losses of P from transplanted sod that received 200 kg P/ha as manure before harvest was comparable to the control and bare soil.

During monitoring Period II, an application of 50 kg N/ha to all treatments after the first rain event minimized differences in runoff losses of total N among treatments on two later rain events (data not shown) (Table 1). Small rain and runoff amounts limited P losses 11 and 12 d after treatments were imposed, but runoff losses after manure and fertilizer P applications on establishing turf were 54 to 150 percent greater than transplanted sod. During a large rain event (4.3 cm) 26 d after treatments were applied, runoff losses of P for both manure rates were greater than or equal to losses from transplanted sod produced with manure at the rate of 400 kg P/ha. The P losses in runoff were comparable for the control and sod transplanted from plots that received 200 kg P/ha as manure or 50 kg P/ha as fertilizer.

During monitoring Period III, total N losses in runoff were not significantly (P=0.05) different among treatments during 4 rain events after manure and fertilizer were applied to establishing turf and transplanted sod (data not shown) (Table 1). Nitrate and dissolved P losses in runoff differed significantly (P=0.01) among treatments and 4 rain events after treatments were applied (Table 1). N fertilizer applications contributed to greater Nitrate losses in runoff from transplanted sod than from the control or establishing turf that received manure only. The P applications as manure or fertilizer contributed to larger dissolved P losses in runoff from establishing turf and transplanted sod than from unfertilized treatments. Dissolved P losses in runoff from transplanted sod produced with 200 kg/ha of manure P was similar to the control during 3 of 4 rain events. In conclusion, transplanted sod produced with 200 kg of manure P will contribute no more dissolved P to surface runoff than extractable soil P at agronomic threshold concentrations. Imports of composted manure as residues in transplanted sod pose less of a threat to surface water quality than import and surface application of composted manure on establishing turf.

Replicated lysimiters.
Tifway sod produced with 200 kg/ha P as manure or with fertilizer P will be harvested from sod plots and transplanted on four replications of the two sod sources on box lysimeters ( 1.5 m L x 1.5 m W x 0.75 m depth) on the Texas A&M University farm. A third treatment in each replication will receive 200 kg P ha-1 y-1 as composted manure after Tifway is vegetatively propagated in soil of lysimeters. Slow infiltration and percolation and large residual P and N concentrations in a silty clay loam necessitated substitution of a coarser texture (sandy loam) in lysimeters. New soil will be used to fill lysimeters and initiate treatments during Spring, 2002. Losses of P and N from the surface layer, including leaching into and through soil will be monitored after treatments are implemented.

Operational and economic feasibility.
Drs. Wolfe and Bosche, subcontractors from Virginia Tech, are using nonpoint simulation models to evaluate P and N losses through runoff and leaching for various manure and fertilizer rates, slopes, and soil types during production and after sod is transplanted. Simulations of two field-scale models, GLEAMS and EPIC, were compared to runoff observations for bermudagrass sod that received applications of composted dairy manure or inorganic fertilizer from Fall 1998 to Spring 2000. Input data files for simulations were constructed from data for experimental treatments (soil type, size, type of grass, mowing) on the 8.5 percent slope of bermudagrass. Both models were calibrated with respect to runoff volumes. It was necessary to modify GLEAMS to allow for a lower hydraulic conductivity below the root zone for more accurate runoff results. The calibrated models were used to estimate N and P losses for the conditions of each treatment on the bermudagrass plots. The calibrated model predictions of rainfall runoff matched measured results well for both GLEAMS and EPIC. For the eight rain events simulated, GLEAMS over-predicted sediment-adsorbed N by 30.2 percent. In contrast, GLEAMS under-predicted sediment-adsorbed P by 11.0 percent. Generally, the GLEAMS predictions of sediment-bound N and P were acceptable. The model is more applicable for long term predictions than for individual events over the short term of the runoff experiments.

The EPIC simulations over-predicted dissolved nitrate in runoff of the eight rain events, except for the largest measured rain amount. The GLEAMS model predicted dissolved NO3 more accurately than EPIC did. Both models under-predicted the largest measured loading. Similarly, both models greatly under-predicted dissolved P in runoff. The GLEAMS predictions of dissolved P in runoff were particularly small. Additional input files will be developed for transplanted sod produced with manure and fertilizer P and manure applications after sod harvests on the 8.5 percent slope.

Economic analyses.
Drs. Lard of Texas A&M University and Bosch of Virginia Tech will provide leadership for evaluations of the economic feasibility of the sod and dairy enterprises. Dr. Lard has developed preliminary enterprise budgets to compare costs and returns between fertilizer and manure sources of P and N in sod production. In addition, enterprise budgets of dairies will be developed to assess net returns with and without the system for exporting N and P through sod.

Table 1. Treatments applied on 8.5 percent slope excavated on a Booneville
Fine Sandy Loam soil (fine, smectitic, thermic Ruptic-vertic Albaqualf).
————- Monitoring Periods ————–
______I____ _____II_____ _____III_____
Treatment P Source P N _P N _P N
————————— kg ha-1———————-
M 84P Manure (1) 84 208 0 50 100 150
M 42P Manure (1) 42 104 0 50 50 75
Con. Soil 0 0 0 50 0 0
F 50P Fertilizer (1) 50 50 0 50 50 50
MSd 400P Trans. Sod (2) 0 0 0 50 0 50
MSd 200P Trans. Sod (2) 0 0 0 50 0 50
Bare soil Soil 0 0 — — — —
FSod 50P Fertilizer (2) — — 0 50 50 50
(1) P & N sources were broadcast on establishing turf
(2) P & N sources were broadcast on transplanted sod produced with
manure (MSd) or fertilizer (FSod) source of P and N.

Impacts and Contributions/Outcomes

The learning system of this project has provided technical information and fostered development of collaborative ventures between livestock and turf producers. For example, the joint venture in Zoysiagrass sod production between Gardner Turfgrass, Inc. and Stoney Point AgriCorp., Inc. emerged from research studies and critical conversations among participants in this project. In addition, new pathways for exporting manure P and N from impaired to less impacted watersheds and between turf and livestock industries are being developed. The turf production and export system of this project is providing an alternative to government-subsidized exports of composted manure from impaired watersheds in Texas. In addition, imports of composted dairy manure in a sod product reduces potential runoff losses of P compared to surface applications of inorganic P fertilizer or composted dairy manure on establishing turf.

Collaborators: