Nitrogen Nutrition of Crop Plants: Soil Nitrogen Vis-À-Vis Fertilizer Nitrogen

ADÜ ZİRAAT DERG, 2018;15(1):127-133 — doi:10.25308/aduziraat.393466 Derleme / Review Nitrogen Nutrition of Crop Plants: Soil Nitrogen Vis-À-Vis Fertilizer Nitrogen Bijay SINGH1 , Mustafa Ali KAPTAN*2 , Gönül AYDIN2 , Mehmet AYDIN2 Seçil KÜÇÜK KAYA2 , Özlem ÜSTÜNDAĞ2 , Saime SEFEROĞLU2 1 2 , Punjab Agricultural University, The Department of Soil Science, Ludhiana 141 004, Punjab, India. Adnan Menderes University, Agricultural Faculty,The Department of Soil Science and Plant Nutrition, Aydın, Turkey. Abstract: In unmanaged ecosystems, soil nitrogen (N) released through mineralization of organic matter constitutes the source of N for the plants. In agro-ecosystems, N is applied additionally as mineral or organic fertilizers in order to compensate N which is removed with products. Adequate and timely application of fertilizer N as dictated that by contribution of soil N to crop production is important for minimizing production costs from overuse of N fertilizer and for reducing possible environmental impacts. Using 15N-labelled fertilizers, it has now been convincingly proved that majority of the plant N comes from the soil N. Thus, soil N plays a vital role in supplying N to crop plants and dictates the efficiency of applied fertilizer N. Size of available N pool, though relatively small as compared to total soil N, throughout the crop growth season determines whether crop gets adequate N nutrition or N is lost from the soil-plant system. As fertilizer N contributes directly to available N pool and by N substitution to the soil organic matter pool, N management at that point following the principles of synchrony between crop N need and application of N through soil and fertilizer N can lead to high fertilizer NUE (nitrogen use efficiency). Evaluation of site-based N management in cereals using gadgets like chlorophyll meter, leaf colour chart or optical sensors or OTG (on the go) crop sensing spreaders revealed that same yields can be achieved with less N fertilizer applied but with enhanced fertilizer NUE and diminished losses of N to the environment. Keywords: soil nitrogen, N use efficiency, fertilizer, environment. Bitkilerinin Azot Beslenmesi: Toprak Azotu Karşısında Gübre Azotu Öz: Yönetilmeyen ekosistemlerde, organik maddenin mineralizasyonu yoluyla salınan toprak azotu (N) bitkiler için N kaynağı oluşturmaktadır. Tarım ekosistemlerinde, topraktan kaldırılan N' u telafi etmek için mineral gübreler veya organik gübreler uygulanmaktadır. N gübresinin uygun bir şekilde ve zamanında uygulanması, üretim maliyetlerini azaltmak, N gübresinin fazla kullanılması ve olası çevresel etkilerin azaltılması için önemlidir. 15N etiketli gübreler kullanılarak yapılmış çalışmalarla, bitki N içeriğinin büyük bir kısmının toprak azotundan geldiği ikna edici bir şekilde kanıtlanmıştır. Böylece, toprak N’u, bitkilerinin N ihtiyacının karşılanmasında hayati bir rol oynamakta ve uygulanan N’lu gübre, verimliliği belirlemektedir. Toprağın toplam N içeriğine kıyasla nispeten çok az olan alınabilir N havuzunun büyüklüğü, bitkinin yeterli N beslenmesini yada toprak- bitki sisteminden N kaybını belirler. Azotlu gübreleme ile doğrudan mevcut alınabilir N havuzuna katkıda bulunulması ve toprak organik madde havuzuna N ikame edilmesi, bitkinin N ihtiyacı ile toprak ve gübrenin N arzı arasındaki senkronizasyon ilkelerini izleyen alana özgü spesifik N yönetimi, yüksek azotlu gübre kullanım etkinliğine neden olabilir. Serin iklim tahıllarında alana özgü spesifik N yönetiminde, klorofil metre, yaprak renk şeması, optik sensörler veya hareketli bitki algılama sensörleri gibi aygıtların kullanılması sonucunda daha az azotlu gübre ile aynı verim değerleri elde edilmiş ancak N kullanım etkinliği artmış ve çevreye karışan N kayıplarının azaldığı tespit edilmiştir. Anahtar Kelimeler: toprak azotu, N kullanım etkinliği, gübre, çevre INTRODUCTION Introduction of industrial sources of nitrogen (N) in the form of mineral fertilizers to farms around the world during the middle of the 20th century was one of the most remarkable transformations in agriculture. Almost half of the alive people live in the world due to N fertilization, which improve crop production. (Erisman et al., 2008). However, only a part of the fertilizer N is used by plants in farm practices (Balasubramanian et al. 2004) and rest of N comes from soil N. Accumulation of N in organic forms in the soil is a typical property in both not controlled and controlled agrosystems. Nitrogen, released mineralization or immobilization process is taken up by plant roots but natural ecosystems often exhibit a high degree of temporal and spatial synchrony and synlocation between N released and N uptake by mixed plant communities. In contrast, agricultural ecosystem are relatively open with respect to N cycling as these produce biomass suitable for consumption outside the system, and N is applied externally as fertilizers and manures to compensate for N removed in exported products. In modern agrosystems, owing to consuming of 300 kg N ha-1 by plants, each year mineral and organic fertilizers or biological N fixation is necessary to sustain productivity (Cassman et al., 2002). When adequate amounts of fertilizer N are not applied to the soil, it is mined of N.  Adnan Menderes Üniversitesi Ziraat Fakültesi Dergisi Intensive cropping in agro-ecosystems shows great N uptake in active but often relatively short growth phase. The large pool of N in agricultural soils exists in organic combinations. As an integral constituent of soil organic matter, soil N also serves as an index of soil health. Soil N may provide 20 to 80% of the plants N requirement (Broadbent, 1984). To achieve optimum yields, remaining N has to be supplied through fertilizer, but many research have shown that annual fertilizer N inputs exceed N exports in crop harvest by 40% to >100%, and leads to N release to the environment (Galloway and Cowling 2002). Adequate and timely application of fertilizer N as dictated by contribution of soil N to crop production is important for minimizing overuse of N fertilizer and for reducing possible environmental impacts. This paper attempts to provide an understanding of relative contribution of soil and fertilizer in meeting N requirement of cereal crops and how application of fertilizer N can be synchronized with soil N to obtain high fertilizer NUE. Sorumlu Yazar: Geliş Tarihi: 12 Şubat 2018 Kabul Tarihi: 4 Haziran 2018  ISSN 1304–7787  2004–2018 127 Nitrogen Nutrition of Crop Plants: Soil Nitrogen Vis-À-Vis Fertilizer Nitrogen Nitrogen uptake by crops from soil and 15N-labelled N Average ratio was found 44% among regions and crops. The fertilizers International Atomic Energy Agency (IAEA, 2003) reported that Tracer studies contain adding a small amount of 15N-enriched the average rate of one time applications of 15N fertilizer 15 (sometimes N-depleted) substrates to label a fertilizer source, recovered in aboveground part of the crop p (...truncated)