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C. Sudhalakshmi ¹, V. Velu ¹, T. M. Thiyagarajan ¹

Affiliations
1 Department of Soil Science and Agricultural Chemistry, Tamil Nadu Agricultural University, Coimbatore-641 003, IN

Abstract

Leaf Colour Chart (LCC) has substituted chlorophyll meter (SPAD) to estimate the leaf nitrogen (N) status of rice (Oryza sativa L.) and for timely N fertilizer application. It is an inexpensive, simple and easy to use tool with six shades of greenness from light yellow to dark green. LCC readings are taken once in a week, starting from 14 days after transplanting for transplanted rice and 21 days after seeding for wet seeded rice. Readings are taken once every 7-20 days until the first flowering. The critical value is 3 for varieties with light green foliage and 4 for all other varieties and hybrids. If the critical value of the leaf falls below the threshold value, 35 kg N/ha during kar/kuruvai/navarai and 30 kg N/ha during samba/thaladi/pishanam season need to be applied. As nitrogen supply matches with the crop demand, there is considerable yield increase under LCC-N management and because of the optimum N supply, there is saving of nitrogenous fertilizers to the tune of 20-40 kg/ha.

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K. Ramamoorthy ¹, A. C. Lourduraj ¹, T. M. Thiyagarajan ¹, M. Prem Sekhar ², B. A. Steware ²

Affiliations
1 Directorate of Soil and Crop Management Studies, TNAU, Coimbatore- 641003, IN
2 Dryland Agriculture Institute, West Texas, US

Abstract

Most of the food and fibre production of the world is achieved under rainfed conditions. Among the various agronomic practices that could bring about immediate positive results in dryland areas, optimum and effective weed control is the first and foremost management practice. Hence, in this paper, an attempt has been made to review the weeds of dryland crops and cropping systems, factors influencing weed flora in dryland regions, critical period of crop weed competition, weed management in major dryland crops and cropping systems, tillage and weed management in dryland agriculture and future research priorities in the field of weed management in dryland agriculture.

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T. M. Thiyagarajan ¹, M. R. Backiyavathy ¹, P. Savithri ¹

Affiliations
1 Centre for Soil and Crop Management Studies, Tamil Nadu Agricultural University, Coimbatore-641003, IN

Abstract

Nutrient imbalance is one of the major abiotic constraints limiting productivity of pulses. The inbuilt mechanism of biological N₂ fixation enable pulse crops to meet 80-90 per cent of their nitrogen requirements, hence a small dose of 15-25 kg N/ha is sufficient to meet out the requirement of most of the pulse crops. However, in emerging cropping systems like Rice Chickpea a higher dose of N (30-40 kg/ha) had shown beneficial effect-Phosphorus deficiency in soils is wide spread and most of the pulse crops have shown good response to 20-60 kg P₂O₅/ha depending upon nutrient status of soil, cropping system and moisture availability. Response to potassium application is location specific. In the recent years, use of sulphur(20-30 kg/ha) and some of the micronutrients such as Zn, B, Mo and Fe have improved productivity of pulse crops considerably in many pockets. Band placement of phosphatic fertilizers and use of bio-fertilizers enhance the efficiency of applied as well as native P. Foliar nutrition of some micronutrients proved quite effective. The amount and mode of application is determined by indigenous nutrient supply, moisture availability and genotypes. Balanced nutrition is indispensable for achieving higher productivity. At the same time, in view of increasing nutrients demand, there is immense need to exploit the alternate source of nutrients viz., organic materials and bio-fertilizers to sustain the productivity with more environment friendly nutrient management systems. The environmental issues and other hazards emerging out of the imbalanced use of nutrients should also be addressed properly.

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K. Ramamoorthy ¹, T. M. Thiyagarajan ¹, S. V. Subbaiah ²

Affiliations
1 Department of Agronomy, Tamil Nadu Agricultural University, Coimbatore-641003, IN
2 Division of Agronomy, Directorate of Rice Research, Hyderabad - 500 030, Andhra Pradesh, IN

Abstract

This review article consolidates more information with special reference to effect of legumes and green manures integration on rice based cropping systems of the Tropics both in normal soil as well as problem soils. The factors influencing the nitrogen dynamics in soil by addition of food legumes and green manures besides their influence on the rice production and productivity in lowland irrigated conditions are also briefly reviewed because nitrogen is the most limiting nutrient in rice production world wide and inclusion of legumes and green manures with their wider adaptability to different rice cultures and their ability to fix nitrogen offer high scope to increase and sustain productivity and income in rice based cropping systems.

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K. Ramamoorthy ¹, A. Christopher Lourduraj ¹, S. Kumaran ¹, T. M. Thiyagarajan ¹

Affiliations
1 Department of Agronomy, Tamil Nadu Agricultural University, Coimbatore - 641003, IN

Abstract

Field experiments were conducted during kharif and rabi 2000 to study the influence of short duration grain legumes (cowpea and greengram) on the productivity of succeeding finger millet under rainfed conditions. Results revealed that maximum dry matter production and vegetable yield was obtained in cowpea (CO 2), as compared to greengram (Pusa bold). In succeeding finger millet crop, higher grain and straw yield were obtained when the haulms of previous cowpea were incorporated after harvest for vegetable purpose. Transplanting of finger millet with phosphorus application recorded higher grain yields as compared to other treatments.

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