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G. KRISHNA REDDY*, A. MUNEENDRA BABU, P. MAHESWARA REDDY AND T. PRATHIMA
Principal Scientist, RARS, ANGRAU, Tirupati – 517 502, Chittoor Dt., A.P.
A field experiment was conducted for three consecutive years (2010-11, 2011-12 and 2012-13) on sandy clay loam soils at RARS farm, Tirupati during rabi season to study the response of maize to the graded levels of nitrogen and phosphorus. The experiment consisted of twelve treatments with four nitrogen levels i.e. 100, 150, 200 and 250 kg N ha-1 and three levels of phosphorus i.e. 30, 60 and 90 kg P2O5 ha-1. The experiment was laid out in randomized block design with factorial concept and replicated thrice. Application of nitrogen @ 250 kg ha-1 had recorded the highest grain yield which was significantly superior
over N100 and N150 kg ha-1 however it is on a par with N200 kg ha-1. The grain yield of maize did not influenced significantly by different levels of phosphorus. However, application of nitrogen @ 200 kg ha-1 in combination with 30 kg P2O5 ha-1 recorded statistically non measurable grain yield. The other parameters such as plant height and yield attributes such as cob length and test weight followed the same trend. Nitrogen requirement for rabi maize was found to be 200 kg ha-1 with application of phosphorus @ 30 kg ha-1 that would be optimum for realizing optimum yield.
Maize, nitrogen and phosphorus levels, yield attributes and kernel yield.
Maize (Zea mays L.) is an important cereal food crop of the world with the highest production and productivity as compared to rice and wheat. It is the third most important cereal after rice and wheat as human food, contributing to 9 per cent of India’s food basket and 5 per cent to World’s dietary energy supply (Saikumar et al., 2012). Maize production has increased more than 12 times from a mere 1.73 million tons in 1950-51 to 21.57 million tons in 2011-12 and currently maize is grown on 9.3 million hectares with production of 24.2 million tons and with a productivity of 2602 kg ha-1 in India (FAO STAT, 2014). In Andhra Pradesh (13 districts), it is cultivated in an area of 1.2 lakh hectares with a production of 6.65 lakh tons and productivity of 5546 kg ha-1.
Demand of maize grain for poultry, livestock, fish and wet and dry milling industries is expected to increase from current level of 21.57 million tonnes to 45 million tonnes by 2030 (DMR, 2011).To meet the growing demand, enhancement of maize yield in coming years across all the growing locations in India is the big challenge. There is little scope for horizontal expansion of this crop. The challenge of achieving higher productivity of maize can be realized only through nutrient management. Hence, an attempt was made to study the response of maize to graded levels of N and P during rabi.
A field experiment was conducted on sandy clay loam soil of Regional Agricultural Research Station, Tirupati consecutively for three years during rabi 2010-11, 2011-12 and 2012-13 respectively. The experimental field had a pH of 7.8, EC of 0.15 dSm-1, low available nitrogen (172 kg ha-1) medium available phosphorus (32 P2O5 kg ha-1) and available potassium (221 K2O kg ha-1). A total rainfall of 15.50 mm and 37.20 mm and 296mm was received during 2010-11, 2011-12 and 12-13 respectively. (Table 1). The experiment was laid out in randomized block design with factorial concept and replicated thrice. The twelve treatments consisted of four nitrogen levels i.e. 100, 150, 200 and 250 kg N ha-1 and three levels of phosphorus i.e. 30, 60 and 90 kg ha-1. Hybrid from M/s Kaveri Seeds (Kaveri) was used during all the years of study. The field was well prepared with the help of tractor drawn cultivator twice and rotavator once to get fine tilth. Later ridges and furrows were made with ridgemar at a spacing of 60 cm. Seeds were sown at intra row spacing of 20 cm. Nitrogen was applied in four
equal splits. One fourth dose at the time of sowing, remaining three doses at 25-30, 45-50 and 60-65 days after sowing (DAS) and phosphorus fertilizers were applied basally as per the treatments and a common recommended dose of potassium (60 kg K2O ha-1 ) was also applied at the time of sowing uniformly for the entire experimental field. Atrazine @ 2.0 kg ha-1 was sprayed immediately after sowing of maize seeds as pre-emergence herbicide in order to control weeds in the initial stages. Prophylactic measures were taken in maize crop as and when required. Initial and final soil samples were taken for analysis of various physico-chemical properties. The data on growth and yield attributes viz., cob length, number of kernels per cob, test weight, kernel and stalk yield and uptake of nitrogen and phosphorus were recorded and subjected to statistical analysis as per Panse and Sukhatme (1978).
a) Treatments:
Nitrogen levels (kg ha-1) Phosphorus levels (kg ha-1)
N1: 100 P1: 30
N2: 150 P2: 60
N3: 200 P3 : 90
N4: 250
A common dose of 60 kg K2O ha-1 was applied uniformly to all treatments.
a) Replications : Three
b) Design : Randomized Block Design with factorial
concept
c) Spacing : 60 cm x 20 cm
d) Hybrid : Pinnacle
f) Irrigation : as and when required
g) Plot size : 5.4 m x 5.0 m
f) Duration : Three seasons
RESULTS AND DISCUSSION
All the weather parameters were congenial for realizing higher productivity of maize during the three consecutive years (Table 1). Maximum temperature during these seasons ranged from 30.60°C to 33.17°C.
Sunshine hours ranged from 7 to 7.95 hours. Evaporation ranged from 3.9 to 5.4 mm per day.
During rabi 2010- 11, plant height of maize was significantly influenced by different levels of nitrogen. The tallest plant height (275.4 cm) was recorded with
250 kg N ha-1. The shortest plants were recorded with lowest level of N (183.6 cm). Phosphorus levels did not show any influence on plant height. There was no interaction effect between N and P levels on plant height. Cob length was significantly influenced by N levels. The largest cobs were recorded with 250 kg N ha-1 which was significantly superior over cobs recorded at lowest N level (100 kg ha-1), however it was on a par with 150 and 200 kg N ha-1. Cob girth was also highest with 250 kg N ha-1 which was significantly superior over lowest N level (100 and 150 kg ha-1), however it was on a par with 200 kg N ha-1. Neither P levels nor interaction with N levels were found significant on cob girth. Test weight of maize grains were not influenced by N, P levels and their interaction. Among nitrogen levels, the highest seed yield was recorded with application of N @ 250 Kg ha-1. However, it is comparable with application of N @ 200 kg ha-1. Progressive increment in seed yield was recorded with increasing levels of nitrogen from 100 to 250 kg ha-1. The yield differences were not significant with respect to phosphorus application. Enhanced levels of nutrient supply exerted a significant and positive influence on the kernel yield of maize. Graded levels of N have profound influence on the kernel yield of maize. Nitrogen is a critical input in agriculture and is a powerful tool for increasing the grain yield in cereals. Maize has maximum nitrogen use efficiency of about 50 per cent, but under poor management, its efficiency varies from 30 – 40 per cent (Patel et al., 2006). Among the major nutrients, P ranked next to N in its importance because of its vital
role in major life processes and its availability to the growing crop in required levels is of very important. Application of phosphorous in a balanced proportion with other essential nutrients has produced higher yields and ensured more profit to the farmers (Manimaran and Poonkodi, 2009). Similar trend was recorded in all the three consecutive years except during 2011-12 where in interaction of N with P levels was found to be significant. Interaction effects showed that application of N @ 200 kg ha-1 along with P2O5 @ 60 kg ha-1 recorded highest seed yield (6606 kg ha-1).
The pooled data of 2010-11, 2011-12 and 2012-13 also revealed that significant differences in yield were observed among nitrogen levels (Table 6). The response was significant up to 200 kg ha-1 which recorded seed yield of 5672 kg ha-1. Highest level of nitrogen i.e. 250 kg N ha-1 recorded seed yield of 5905 kg ha-1 but was on par with 200 kg N ha-1 (5672 kg ha-1). Significant differences were not observed among phosphorus levels tested. Tyagi et al. (1998) observed an increase in grain yield of maize from 61 to 137 per cent with increased levels of N application from 75 to 250 kg ha-1 over that of no nitrogen on sandy loam soils of Hissar, Haryana. Patel et al. (2006) also reported that with increasing levels of N from 75 to175 kg ha-1 also improved all the yield attributes and grain yield of maize in alfisols of Anand, Gujarat. Increased dry matter production with increased nitrogen application coupled with P increased biomass as reported by Wadsworth (2002). Thus greater availability of photosynthates, metabolites and nutrients to develop reproductive structures seems to have resulted in increased dry weight of grain. Enhanced levels of nitrogen supply exerted a significant and positive influence on the kernel yield of maize.
Results revealed that nitrogen requirement for rabi maize was found to be 200 kg ha-1 with application of phosphorus @ 30 kg ha-1 would be optimum for realizing profitable grain yield in maize.