Agriculture Reference
In-Depth Information
Fig. 7.3
The garden organ-
ics compost (cGO) being
weighed out for distribution
to compost treatment plots
for the second application
of compost prior to plant-
ing crop 6—capsicum at the
CROA field experiment site
High and low initial levels of soil extractable P was included as a factor in the
experimental design because high P levels were found to be typical of vegetable
farm soils in the Sydney basin (Chan et al.
2007a
,
b
) and as such it was considered
important to assess the impact on vegetable production (Chan et al.
2008
). For the
high P treatments (T1, T2 and T3), triple superphosphate was applied to each plot
at a rate equivalent to 680 kg P ha
−1
and incorporated to 0.10 m, to raise the soil ex-
tractable P concentrations to levels similar to those observed in vegetable farm soils
(~ 250 mg/kg in 0.10 m, Chan et al.
2007a
,
2008
) prior to the commencement of the
field experiment. The site soil had a low initial concentration of bicarbonate extract-
able P (29 mg/kg) and as such ensured the other treatments (T4, T5, T6, T7) were
representative of new vegetable farms with no prior history of high fertilizer inputs.
The compost used was derived from source separated garden organics blended
with 10 % poultry (laying chickens) manure that was composted according to the
Australian Standard AS 4454-2003. The properties of the compost and poultry ma-
nure used in this field trial are presented in Table
7.1
. The compost used in the
experiment is shown in Fig.
7.3
along with its application to the compost treatment
plots prior to incorporation in Fig.
7.4
.
In the case of these treatment descriptions, half refers to half the recommended
dosage of total chemical NPK fertilizer application rates which was based on crop
specific industry expert recommendations for each crop (NSW DPI Agfact/Prime-
fact series (Agfact/Primefact Series
2013
) and district horticulturalist advice). For
the two organic amendments, poultry manure and compost, the rate was based on
their total nitrogen (N) and an assumed availability index of 0.60 and 0.10 for poul-
try manure and compost respectively (i.e., it was assumed that, 60 % of the poultry
manure total N and 10 % of the compost total N would be available to the crop)
according to Evanylo and Sherony (
2002
). For the chemical fertilizers, phosphorus
was applied as Triple superphosphate and incorporated into the soil to a depth of
0.10 m prior to crop seedling planting, whilst potassium and nitrogen were applied
as muriate of potash and urea respectively, in split surface applications over the
