Agriculture Reference
In-Depth Information
Table 4.2
NDVI values for different tea fields representing St. Joachim and Palm garden estates
Sample
19920210 1992313
2001209
2002
2005
20060123 2006303
1
0.232
0.15
0.292
0.403
0.381
0.188
0.312
2
0.288
0.237
0.283
0.385
0.348
0.153
0.303
3
0.267
0.175
0.171
0.175
0.583
0.297
0.6
4
0.333
0.537
0.226
0.443
0.641
0.184
0.597
5
0.333
0.276
0.27
0.343
0.4
0.171
0.528
6
0.314
0.414
0.333
0.267
0.406
0.213
0.541
7
0.218
0.158
0.359
0.113
0.491
0.246
0.291
8
0.461
0.333
0.395
0.314
0.562
0.3
0.231
9
0.472
0.451
0.212
0.37
0.407
0.193
0.38
10
0.307
0.562
0.264
0.3
0.464
0.18
0.218
11
0.377
0.597
0.22
0.429
0.455
0.226
0.338
12
0.355
0.296
0.26
0.388
0.394
0.207
0.534
13
0.295
0.304
0.281
0.237
0.417
0.252
0.48
14
0.358
0.327
0.236
0.365
0.476
0.161
0.592
type of pixel misclassification was observed by Samarasinghe (
2003
). Therefore,
pixel values of rubber, coconut or home gardens also need to be studied intensively
in order to classify actual tea estates in synoptic scale.
4.2 NDVI analysis
Normalized difference vegetation index maps for 1992, 2001, 2002, 2005, and 2006
were generated from satellite images. (Plate 34) Representative 7 tea fields from
each estate (St. Joachim and Palm garden) were identified and NDVI values were
taken (Table
4.2
). Annual yield of tea estates was then correlated with NDVI values.
The correlation was insignificant with annual yield, hence further studies are neces-
sary with short-term (monthly or weekly) yield data. As it can be broadly seen from
NDVI images as to which area is having green cover and which is fallow, it offers a
promising tool to evaluate the yield of different seasons. Hence, further refinement
of pixel-to-yield correlation is necessary which is better done with high resolution
imagery (Fig.
4.9
).
5 Conclusion
Soil samples and groundwater samples were collected from the area of interest
which is located in a district of low-country wet zone. The following conclusion
can be drawn out from the results that were obtained.:
1. Soil is dominated by sand fraction and higher gravel content.
2. Further, quartz, calcite and hematite are the major minerals in the soil samples.
