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Varinderpal-Singh Kunal Kaur Rajinder Mehtab-Singh Mohkam-Singh Harpreet-Singh Bijay-Singh 《Precision Agriculture》2022,23(3):733-747
Precision Agriculture - The present study was conducted to establish prediction models for grain yield and nitrogen (N) uptake using normalized difference vegetation index (NDVI) measurements with... 相似文献
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Varinderpal-Singh Yadvinder-SinghBijay-Singh H.S. ThindAjay Kumar Monika Vashistha 《Field Crops Research》2011
Large field to field variability restricts efficient fertilizer N management when broad based blanket recommendations are used in maize (Zea mays L.). To achieve higher yields and to avoid nitrogen (N) deficiency risks, many farmers apply fertilizer N in excess of crop requirement in maize. Field experiments were conducted for five years (2005–2009) to establish and evaluate threshold leaf colour to guide in-season need based fertilizer N topdressings in four maize genotypes. Colour (of the first top maize leaf with fully exposed collar) as measured by comparison with different shades of green colour on a leaf colour chart (LCC) and maize grain yield was significantly correlated. The Cate–Nelson plot of chlorophyll (SPAD) meter/leaf colour chart values against relative grain yield of 0.93 for the experiments conducted during first two years indicated that LCC shade 5 during vegetative growth stages and LCC shade 5.5 at silking stage (R1) can guide crop demand driven N applications in maize. Evaluation of the established threshold leaf greenness during the next three years revealed that fertilizer N management using LCC 5 starting from six-leaf (V6) stage to before R1 stage resulted in improved agronomic and N recovery efficiency in different maize genotypes. There was no response to fertilizer N application at R1 stage. The study revealed that in maize, fertilizer N can be more efficiently managed by applying fertilizer N dose based on leaf colour as measured by LCC than blanket recommendation. 相似文献
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Yadvinder-Singh R. K. Gupta H. S. Thind Bijay-Singh Varinderpal-Singh Gurpreet-Singh Jagmohan-Singh J. K. Ladha 《Biology and Fertility of Soils》2009,45(7):701-710
Poultry litter (PL) is an important nutrient source; however, no information is available regarding its value in supplying
N and P in rice–wheat (RW) production. A three-year field study was conducted at Ludhiana, Punjab, India on a loamy sand soil
to identify optimum combination of PL and N and P fertilizers for a sustainable RW production. The litter was applied to rice
at 5 Mg ha−1 as a single application and supplemented with different rates of N. The residual effect of PL and the direct effects of the
different combinations of N and P were studied in the following wheat. Nitrogen and P mineralization from PL was studied under
controlled conditions in the laboratory, and macronutrient input–output balances were estimated from field results. About
46% of the N from PL was released after 60 days of incubation. The release of P from the PL occurred mainly during the initial
20 days after incubation, accounting for 15–17% of the total P. Combining PL with fertilizer N (40 kg ha−1) increased rice yield and nutrient uptake similar to what was obtained with the application of recommended fertilizer N (120 kg
ha−1). In the following wheat, the residual effect of PL was equal to 30 kg N ha−1 and 13 kg P ha−1. After three annual cropping cycles and PL application, mean soil organic C increased by 17%, Olsen-P by 73%, and NH4OAc-extractable-K by 24%. Most treatments had positive P but negative K balances. About 11% of the net P balance was recovered
from the soil as Olsen-P. The study showed that optimum N and P fertilizer doses for an RW system receiving 5 Mg ha−1 of PL are 40 kg N ha−1 for rice and 90 kg N + 13 kg P ha−1 for the following wheat. Safe and effective management of PL should be based on P balance, particularly when regular applications
of PL are to be made in the RW system. 相似文献
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