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Abstract:The magnitude of yield reduction due to soil compaction is variable and depends on the soil type, fertility status and other soil and environmental factors. The present investigation was carried out at the research farm, Department of Soil Science, Punjab Agricultural University, Ludhiana. The experiment was conducted to evaluate the effect of different levels of subsoil compaction and nitrogen fertilization on maize phenology, yield and heat use efficiency ) treatment during the year 2012 and 2013, respectively. The tasseling and silking stage was delayed, while physiological maturity was advanced under C 2 subsoil compaction treatment than that in C 0 treatment. The N 2 treatment improved the yield by 14.9 and 13.9 % and HUE by 15.2 and 14.3 % than that in N 0 treatment during the year 2012 and 2013, respectively. Maize took more days to reach physiological maturity under N 2 treatment as compared to N 0 treatment. Phenothermal index (PTI) showed that crop reached different stages earlier under C 1 and C 2 than that of C 0. The data emphasized the need to take care of soil strength and soil temperature related parameters along with weather conditions for better yield prediction using thermal time.

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Soil erosion, a serious problem in Submontane Punjab, India, has been intensively studied by a number of investigators. Various soil management practices, such as the use of diverse crops, strip cropping, increasing crop cover, multiple cropping, agroforestry, mulching, conservation tillage, ridging, and furrowing have decreased erosion. Maize at a spacing of 60 cm x 22.5 cm showed minimum soil loss by runoff. Crops with erect growth and limited tilling allowed for high runoff and soil loss. The intercropping of groundnut with maize gave the highest net return with the least amount of soil loss by erosion; maize with urd (Vigna mungo L.) gave the second highest net return with the least amount of soil loss by erosion. Maize and guar (Cyamopsis tetragonoloba L.) in alternating strips of 9-m width showed minimal runoff (9%) and soil loss (3.3 Mg ha -1 ). The agroforestry practice of growing Leucaena leucocephala Lam. intercropped with maize, guar, or urd also was effective in reducing runoff and soil loss; the yield was reduced for maize by 34%, urd by 27%, and guar by 21% as compared to pure crop but compensated by a relatively higher yield of fodder and fuel from L. leucocephala. The application of 4 Mg ha -1 of mulch decreased runoff by 57.6%, soil loss by 71.7%, and nutrient loss by 60% and increased the yield of maize. Deep tillage increased infiltration and decreased run-off and soil loss. A combination of mulch and tillage further reduced soil losses. Contour cultivation reduced soil loss from 6.3 Mg ha -1 to 2.9 Mg ha -1 as compared to slope cultivation. Ridging and furrowing at sowing was most effective in controlling soil loss (0.3 Mg ha -1 ); ridging and furrowing 30 days after sowing was the second most effective way to control soil loss (1.6 Mg soil loss ha -1 ). On sloping lands contour bunding (embankments) decreased soil loss from 2.56 Mg ha -1 to 0.59 Mg ha -1 and increased wheat yields above 20%. Bench terracing proved to be more suitable for land with slopes between 6-33%. Structures such as waterways, drop structures, and control dams reduced sheet, rill, and gully erosion from 80%, 11%, and 3.6% to 15%, 2%, and nil, respectively. The goal of control practices has been to mitigate erosive capacity of rainfall by integrated management of crop, soil, and runoff and thus to decrease the soil and nutrient loss from arable soils to tolerable limits.

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