Movement of nitrogen in a sandy loam soil under a continuous maize-wheat cropping system
| Autor: | V. K. Verma, R. K. Setia, K. N. Sharma |
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| Rok vydání: | 2006 |
| Předmět: | |
| Zdroj: | Acta Agronomica Hungarica. 54:487-497 |
| ISSN: | 1588-2527 0238-0161 |
| DOI: | 10.1556/aagr.54.2006.4.10 |
| Popis: | Nitrogen (N) movement in the soil resulting from the long-term application of fertilizer N is an environmental concern when it reaches the groundwater. The distribution of N in the profile of an alkaline sandy loam soil (Typic Haplustept) and its relationship with N uptake by plants was studied after 22 years of continuous cultivation in an annual crop rotation involving maize (Zea mays L.) and wheat (Triticum aestivum L.). Soil samples were collected to a depth of 1.2 m from the 0-0.15, 0.15-0.30, 0.30-0.45, 0.45-0.60, 0.60-0.90 and 0.90-1.20 m layers and analysed for alkaline KMnO4-oxidisable N (available N) and mineral N (NH4-N and NO3-N). The continuous addition of increasing levels of N resulted in an increase in N content, whereas the combined application of N, P and K caused a decline in its availability. Mineral N (2 M KCl-extractable NH4-N and NO3-N) was the lowest in the N120P35K33.2 treatment plot. The available N and NH4-N decreased with increasing soil depth. However, variations in NO3-N concentration due to differential rates of fertilizer application were observed only to a depth of 0.45 m. This effect was more pronounced in the N180P17.5K33.2 plot. Regression equations were used to predict N uptake by wheat using the N status in different soil layers as independent variables. Multiple regression analysis indicated that the predictability of the relationship between N uptake and available N improved considerably when its status to a soil depth of 0.45 m was included. In the case of NH4-N, a noticeable increase in the coefficient of determination (R2) occurred to a depth of 0.90 m. The R2 value of NO3-N with the N uptake by wheat was quite low in the top layers (to a depth of 0.30 m). However, an increase in the R2 value was observed when lower depths (beyond 0.30 m) were included in the regression analysis, suggesting that the inclusion of subsoil N status is important to achieve better and profitable N supply systems in crop production. |
| Databáze: | OpenAIRE |
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