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Abstract
Rainfed areas in
general and Pothowar region in particular have great potential to
meet the grain need of the country but there are certain limitations
which affect the crop productivity on these areas. These include
erratic rainfall, depletion of plant nutrients by soil erosion, low
soil organic matter content, soil compaction on nonsloppy lands and
ultimately poor soil moisture availability for crop production. The
limitations can be minimized/overcome by the adoption of soil
management practices such as soil conservation measures, tillage
practices and reducing slopes through terracing. The sloppy lands
have been converted into various types of terraces such as bench
terraces and broad base terraces on which different cropping
patterns are being practiced by the farmers. These patterns include
Wheat-Maize and Wheat-Maize (Fodder) in Kahuta (high rainfall) area,
Wheat-Millet-Fallow and Wheat-Millet-Lentil in Khairimurat (medium
rainfall) area and Wheat-Fallow and Fallow-Groundnut in Pindi Gheb
(low rainfall) area. The crops included in these patterns have more
crop water requirement and if the drought prevails, the yields of
these crops will be significantly affected.
This study was conducted in two different stages. In the first
stage, monitoring and evaluation work was carried out and in the
second stage field experiments were performed at the selected sites
to test the suitability of new cropping patterns. During survey
work, experimental site were selected and soil samples were
collected from these sites for the evaluation of soil fertility
status, soil moisture variation throughout the year, soil microbial
biomass in various seasons. In addition to this, crop yields during
Rabi and Kharif seasons were recorded. The climatic data on rainfall
and temperature were obtained from the meteorological department.
Fertilizer application and management practices adopted by the
farmer were also recorded. The collected soil samples were subjected
to analyses for physico-chemical properties such as particle size
analysis (soil texture), soil moisture release curve, electrical
conductivity (ECe), pH of the saturated soil paste (pHs),
calcareousness (CaCO3), cation exchange capacity (CEC), total
organic carbon (TOC), total nitrogen, soil sodium (Na+), available
potassium (K+), calcium plus magnesium (Ca+2+Mg+2), microbial
biomass carbon (Cmic), microbial biomass nitrogen (Nmic) and soil
enzymes (Alkaline Phosphatase and Dehydrogenase).
The results showed that in September 2007, more average soil water
content was available in high and medium terraces under Wheat-Miaze
and Wheat-Maize (as fodder) cropping pattern in Kahuta area, in high
and low terraces under Wheat-Millet- Fallow and Wheat-Millet-Lentil
cropping pattern in Khairimurat and under Wheat-Fallow and
Fallow-Groundnut in Pindi Gheb areas respectively.
The pysico-chemical characteristics of all the sites showed that the
texture of soil was sandy loam under Wheat-Maize cropping pattern,
sandy clay loam under Wheat-Maize (Fodder) cropping pattern in
Kahuta area, loam under Wheat-Millet-Fallow and Wheat-Millet-Lentil
cropping patterns in Khairimurat area and sandy clay loam under
Wheat-Fallow and Fallow-Groundnut cropping pattern in Pindi Gheb
area. The results of all sites indicated that the soil was alkaline,
calcareous in nature, nonsaline, non-sodic, having marginal total
organic carbon, total nitrogen, adequate available soil potassium
but deficient in available soil phosphorus. The bench terraces of
Kahuta area had more soil fertility on the low height terraces and
broad base terraces of Khairimurat and Pindi Gheb area had more soil
fertility on the upper and medium height terraces. The soil water
release curve indicated that Dhok Tarhan soils had more plant water
availability as compared to the Jagiot Khalsa, Dhupri and Kasran
sites.
Incubation study was conducted in the laboratory to evaluate the
rate of mineralization of different organic substrates in different
soil textures. The treatments tested were viz. 1) control, 2)
Groundnut straw and 3) Wheat Straw (1% on soil weight basis). Soil
samples were taken after 2, 4, 7, 14, 28 and 60 days for the
determination of Cmic, Nmic, Pmic, DH and AP. Completely Randomized
Design (CRD) along with three replications was used for this study.
This study revealed that high rate of mineralization of organic
amendments was on 28 days after incubation under controlled
condition under various textured soils of Kahuta, Khairimurat and
Pindi Gheb areas. This study indicated that incorporated groundnut
straw mineralized after one month in the field for the availability
of nutrients to the crops.
In the second part of the study, field experiments were carried out
at Kahuta, Khairimurat and Pindi Gheb areas. The existing cropping
patterns were Wheat-Maize and Wheat-Maize as Fodder in Kahuta,
Wheat-Millet-Lentil and Wheat-Millet-Lentil in Khairimurat and
Wheat-Fallow and Fallow-Groundnut in Pindi Gheb area. In these
experiments, the high kharief water requirement crops such as Maize
and Millet were replaced with Mungbean having low water requirement.
The modified cropping patterns viz Wheat-Mungbean at both sites in
Kahuta, Wheat-Mungbean-Fallow and Wheat-Mungbean-Lentil in
Khairimurat and Wheat-Mungbean and Fallow-Groundnut in Pindi Gheb
area were tested. The data showed that the modified cropping
patterns performed better as compared to existing cropping pattern.
The plant height, straw yield of mung bean of the modified cropping
pattern was found more as compared to the existing cropping
patterns. The yield of mung bean in modified cropping patterns had
more economic value as compared to the maize and millet crops of
existing cropping patterns in Jagiot Khalsa, Dhupri sites of Kahuta
area and Dhok Tarkhan sites of Khairimurat area. At Kasran sites of
Pindi Gheb area, the Mungbean produced a reasonable yield instead of
keeping the land fallow. The advanced varieties of wheat (GA-2002)
and groundnut (Chakwal-2000) crops of modified cropping patterns
produced more plant height, straw and grain yield as compared to
local varieties adopted by the farming community in existing
cropping patterns at Jagiot Khalsa and Dhupri sites of Kahuta area,
Dhok Tarkhan sites of Khairimurat area and Kasran sites of Pindi
Gheb area. These modified cropping patterns also acted as
restorative crops instead of exhaustive crops and improved the soil
fertility status and increased the grain and straw yield as compared
to the existing cropping patterns. The study concluded with
possibility of growing low water requirement crops during the
drought in summer season, for sustaining cropping patterns and
sustainability of agriculture.
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