Manure and Compost Sample Preparation

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Introduction

Leopold 2000-42: Optimizing swine hoop manure management for soil quality and crop system peformance

Field 16: moisture, bulk density, pH, EC, total organic C, total N, inorganic N, organic and inorganic P, K, CO2 respiration, and cress seed phytotoxicity bioassay
PFI farms. As above, except only one P analysis (not specified)
Both: 1 analysis per field plot and 1 analysis per compost pile at each sampling time. Compositing as below

Procedure

1.Sample collection. Bulk density should be measured in the field using method 2a if possible. For additional analysis a single composite sample should be collected from each compost pile or the manure being spread on each field plot. For each composite, 20 grab samples should be collected (20 trayfuls per plot or 5 depths from each of 4 transects into compost piles) and combined in a 5 gallon bucket. After measuring bulk density of the bucket (see method 2b), mix and subsample to collect a single 0.75 to 1 kg composite sample. Cool sample immediately, or freeze if not homogenized within 24 hours.

2. Measure bulk density

a)Ideally done during field application by striking a manure spreader off level, weighing the load, measuring the spreader and calculating the volume.
b)Place fresh sample in a 5 gallon bucket, tamp 10 times dropped from 6 inches, weigh, measure settled depth and diameter, and calculate volume.
c)Place thawed sample in 2 liter plastic container, tamp 10 times, weigh, measure settled depth and diameter, and calculate volume.

3. Homogenize each sample in Hobart mill. Split sample into 5 bags: 100 g for fresh analysis at LEBRC (pH, EC, moisture); 350 g for cress bioassay at Liebman’s lab; 250 g for CO2 respiration at Richard’s lab; 100 g for acidification at Richard’s lab and ultimately total C and N analysis at Cambardella’s (20 g of ground material will go to Hort lab for ashing and ICP analysis); and 50 g for KCl extraction at Cambardella’s lab. Refreeze CO2 respiration, cress bioassay, acidification and KCl samples if those analyses are not going to be done immediately.

4. EC and pH: Measure in triplicate. Add 150 ml deionized water to 30 g fresh sample. Measure pH and EC with electrodes and calibrated meter. See attached method for complete method description.

5. Moisture: Use remainder of LEBRC sample (100 g – 30 g EC & pH). Record tare weight of tin and fresh weight of tin + manure. Dry at 75°C until constant weight (24 hrs?) and record results. See Method 07.09, Test Methods for Compost Analysis for complete method description.

6. Cress bioassay: Need description.

7. CO2 respiration: 1 incubation for each sample. If samples have been frozen, remove 20 g 1 week before pre-incubation and incubate at 37°C for one week, then blend with thawed sample. Adjust moisture to 50% and pre-incubate for 3 days in unsealed plastic bag. Incubate triplicate 25 g samples in 4L glass jars with NaOH traps for 4 days, titrating and replacing NaOH daily. See attached method for complete method description.

8. Acidification for C and N analysis. 100 g sample are placed in 8 x 5 x 2 tupperware trays. Add 200 ml of 0.5 N HCl and stir with stainless spoon until all compost is submerged. Dry in fume hood with fan for 5-6 days. Grind in Retsch mill and analyze in duplicate in Carlo-Erba CHN analyzer. See attached method for complete method description.

9. Inorganic N analysis using KCl extraction: Analyze in triplicate. See attached method.

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