Cattle diet composition and fertilizer value of excreta

Egbert A. Lantinga

Group of Biological Farming SystemsDepartment of Plant Sciencesegbert.lantinga@wur.nl

Cattle dung

Cattle slurry

Phytotoxicity: lab vs. field experiments

Long(er)-term effects

Outline

(Bosker, Hoekstra & Lantinga, 2002)

Influence of feeding strategy on growth and rejection

of herbage around dung pats and their decomposition- Continously grazed pasture- Experimental period: 6 weeks- Artificial dung pats (2.5 kg fresh dung; Ø 31 cm;

height 9 cm)- Dung from 4 diverging cattle farms

CATTLE DUNG

Grass cages

4 grass cages

Results: Index factors (column mean=100)

Index factors

Cage: undisturbed DM yield (Ø 64 cm)

R1: DM yield within grazed dung area

R2: DM yield around grazed dung area

PDD: % dung disappeared

(+ straw)

Cattle slurry

Low C/N-ratio + high Nmin-content: - phytotoxic effects on herbage? (ammonia, salts, heavy metals, biogenic amines, phenolic compounds)- herbage rejection by grazing cattle? (volatile fatty acids, ammonia and

volatile amines)

Experiments: - bio-assay (germination of cress seeds) - field trial (herbage N recovery and

grazing behaviour: change in sward height in manured plots)

(Reijs, Meijer, Bakker and Lantinga, 2003)

Roughages in cattle diets

Grazed Grass Maize WheatWheat

grass silage silage silage straw APMlac + - - + + OSK + - - - - APMdry - + - + + MAR + + + - -

Bio-assay: Germination index (ammonia)

Bio-assay: Germination index (salinity)

Bio-assay: Germination index (copper)

Bio-assay: Germination index(phenol)

Bio-assay: Germination index

Phytotoxic effect: MAR > APMlac > OSK > APMdry Slurry C/N ratio: 10 9 14 16

Germination inhibiting effects:

1. NH3/NH4+

2. salinity (electronic conductivity)3. Cu (weak)4. Phenol (no)

Grazing behaviour: Change in Herbage Height (CHH; cm) after one week (no fertilizer effects!)

Ranking order

0 N > APMdry > OSK > APMlac > MAR

-1.4 -0.4 -0.2 -0.1 +0.6

Positively and significantly correlated with slurry NH3/NH4

+-N content (R2 = 0.98)

Fertilizer value (growth period 5 weeks)

straw in diets →

0 N

Bio-assay phytotoxicity and field slurry quality

Ranking order: the slurry with the greatest phytotoxicity (lab) showed highest herbage yield after five weeks (field)!

- Buffering capacity soil- Sensitivity differences between roots of cress

seedlings and established grass root systems- Straw (C/N-ratio ~ 80): temporary N-immobilization

Longer term fertilizer effects: one year

Field experiment: effects different diets on N utilization from cattle slurry

MFE (mineral fertilizer equivalent; %) = 100 * EFR / total slurry-N

EFR = equivalent fertilizer N response (i.e. amount of mineral fertilizer N needed to attain the same N yield as with slurry)

Two grassland fields on sand: NEW and OLD (age 5 vs ~50 years); OLD field higher groundwater level → higher denitrification losses (wet spring)

(Reijs, Sonneveld, SØrensen, Schils, Groot and Lantinga, 2007)

NEW

OLD

O

OO

O

O: 50% straw

Long-term soil quality effects (200 years)

Initial and equilibrium topsoil characteristics after long-term applications (180 kg N ha-1 yr-1) of two extreme slurries (C:N

total

14.5 vs. 26.3)

Model: FarmDances (J.C.J. Groot, WUR)

Long-term soil quality effects (200 years)

Inclusion of chopped straw in cattle diets (~5% on DM basis): herbage rejection grazing cattle ↓; dung decomposition rate↑; temporary immobilization slurry Nmin → short-term (one year) N fertilizing effect ~ 0

Lab bio-assays with cress seeds are not realistic to assess phytotoxity of slurry for the field situation

Compensation of reduced first year’s N availability of slurry with high C:Ntotal ratio’s will take some decades (gradually increasing soil N delivery due to N accumulation)

CONCLUSIONS