STUDIES ON SOIL RELATED CONSTRAINTS AND THEIR EFFECT ON YIELD AND QUALITY OF SWEET ORANGE [Citrus sinensis (L.) Osbeck] IN YSR DISTRICT, ANDHRA PRADESH
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Date
2017
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Acharya N.G. Ranga Agricultural University
Abstract
An investigation was carried out to study the soil related constraints and
their effect on yield and quality of sweet orange in YSR district of Andhra
Pradesh. To prosecute this investigation, fifty sweet orange orchards aged between
12 to 13 years were selected and soil samples were collected from these orchards
at 0-30 cm and 30-60 cm depth. Further, fifty index leaf samples, fruit samples
and irrigation water samples were also collected from respective soil sampled
orchards.
The soil samples were analyzed for physical properties like texture, colour,
bulk density, particle density, percent pore space and water holding capacity,
physico-chemical characteristics viz., pH, EC, OC, CEC, SAR, ESP and free
CaCO3 and chemical properties viz., available N, P, K, Ca, Mg, S, Fe, Mn, Zn and
Cu. Similarly, leaf samples were analyzed for total N, P, K, Ca, Mg, S, Fe, Mn, Zn
and Cu and fruit samples were analyzed for per cent juice, titrable acidity, juice
pH, TSS and vitamin-C. In irrigation water, quality parameters such as pH, EC,
cations viz., Na+
, Ca2+, Mg2+, K+
and anions viz., CO3
2-
, HCO3
-
, Cl-
, and SO4
2-
were analyzed.
The various soil textural classes identified were loamy sand (18%), sandy
loam (42%), sandy clay loam (34%) and sandy clay (6%) at surface and sandy
(4%), loamy sand (14%), sandy loam (38%), sandy clay loam (38%) and sandy
clay (6%) at subsurface soils of the study area. The colour of the soils of the study
area had their Munsell colour notation in the hue of 10YR/7.5YR/5YR/2.5YR
with value 2 to 4 and chroma 0 to 4 at 0-30 cm depth and at 30-60 cm depth the
hue of 10YR/7.5YR/5YR/2.5YR with value 2 to 4 and chroma 1 to 6.
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The study area soil reaction varied widely, that indicated about 72% of the
samples were mildly alkaline, 16% were moderately alkaline and 12% were
strongly alkaline at 0-30 cm and at 30-60 cm, 48% were strongly alkaline, 38%
were moderately alkaline and 14% were mildly alkaline in pH. The orchards were
non-saline in nature as the EC of these soils was far below 4.0 dS m-1
. The study
area soils were low to medium in organic carbon at surface and low in sub-surface.
The organic carbon content decreased with increasing depth.
Out of all the soils of sweet orange orchards studied, 82% were deficit in N
and 18% were medium in N, 20% were deficient in P, 60% were medium in P and
20% were high in P, but in case of available K, 32% were in medium range and
68% were in high range. The higher exchangeable calcium and magnesium status
was observed in all the orchards both in the surface and subsurface soils.
In soils of sweet orange orchards studied, 24% and 78% were very low in
available Fe and Zn, respectively. Low in available Fe, Zn and Mn were 68%,
18% and 8%, respectively. Medium in available Fe, Zn Mn and Cu were 8%, 4%,
38% and 18%, respectively. High in available Mn and Cu were 36% and 82%,
respectively. Very high in available Mn was 18%.
Two per cent of the leaf samples deficit in N, 8% deficit in P and 4%
deficit in K. Low in N, P, K, Ca and Mg were 42%, 12%, 14%, 2% and 12%,
respectively. High in N, P, K, Ca and Mg were 4%, 50%, 16%, 18% and 18%,
respectively.
Leaf Zn deficiency was the most severe among the 10 mineral elements
tested and 62% of samples were deficient in Zn, followed by Fe (54%), Mn (52%)
and Cu (26%). However, the average leaf content of N, P Ca and Cu was 2.03,
0.16, 2.66 and 8.29, respectively; which was much more than the optimum range.
The negative significant correlation noticed between fruit yield and soil pH
(r = -0.512**), free CaCO3 (r = -0.329*), SAR (r = -0.424**) and ESP (r = -
0.522**), and also observed a non-significant negative correlation between soil
EC with fruit yield of sweet orange.
Fruit yield and fruit weight was positively and significantly influenced by
soil organic carbon content (r = 0.360* and r = 0.330*), because the organic
carbon content of the soil had a significant positive influence on soil N (r =
0.716**).
The soil mineral nutrients like N, P and K influenced the fruit weight
significantly and positively (r = 0.469**, r = 0.446** and r = 0.415**,
respectively). Fruit juice per cent had significant positive relation with soil N (r =
0.353*) and P (r = 0.364**). Soil P had a significant positive correlation with TSS
(r = 0.438**).
The pH of the water samples collected from sweet orange orchards of study
area was varied from neutral to mildly alkaline.
The EC of the irrigation water varied from 0.82 - 3.87 dS m-1 with a mean
value of 1.82 dS m-1
. According to the irrigation EC classification, 76% of the
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water samples were in high salinity i.e., C3 class and 24% of the water samples
categorized as very high salinity i.e., C4 class.
The concentration of major anions of irrigation water collected from all the
sweet orange orchards were in the order of HCO3
-
> Cl-
> SO4
2-
> CO3
2-
and the
cations were in the order of Na+
> Mg2+ > Ca2+ > K+
.
The general constraints that were observed in the sweet orange orchards
were low organic carbon, low to medium in available nitrogen and phosphorus
content, wide spread deficiency of zinc and iron in the soils, low to medium soil
Mn, wide occurrence of soil alkalinity, calcareousness and poor quality of
irrigation water i.e., high to very high salinity of the irrigation water.
Nutrient constraints can be overcome by regular application of required
doses of fertilizers to the sweet orange orchards on soil and plant test based,
application of liberal doses of manures, adapting integrated nutrient management
system, foliar application of micronutrients and following fertigation technique.
Calcareous soils can be managed by application of sulphur products, such
as elemental sulphur or sulphuric acid (H2SO4) acts as soil acidifiers and these
products potentially improve nutrient availability in calcareous soils by decreasing
soil pH. Sodic soils can be managed by application of gypsum and organic
manures.
Cholorosis can be controlled by foliar application of composite mixture of
zinc sulphate 0.5%, manganese sulphate 0.2%, boric acid 0.1%, urea 1% and lime
0.4% at two or three times in a year.
The detailed study of the sweet orange crop revealed that the yield and
quality of sweet orange grown under adverse soil environment would be reduced
drastically due to the poor management practices. The unfavourable soil
environment will not be suitable for growing sweet orange. For achieving the
maximum yield and good quality, sweet orange crops can be grown in sandy loam
or sandy clay loam soils free from CaCO3 coupled with best management
practices.
Description
D5536
Keywords
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