Nitrogen fluxes at the root-soil interface show a mismatch of nitrogen fertilizer supply and sugarcane root uptake capacity

Abstract

Globally only ≈50% of applied nitrogen (N) fertilizer is captured by crops, and the remainder can cause pollution via runoff and gaseous emissions. Synchronizing soil N supply and crop demand will address this problem, however current soil analysis methods provide little insight into delivery and acquisition of N forms by roots. We used microdialysis, a novel technique for in situ quantification of soil nutrient fluxes, to measure N fluxes in sugarcane cropping soils receiving different fertilizer regimes, and compare these with N uptake capacities of sugarcane roots. We show that in fertilized sugarcane soils, fluxes of inorganic N exceed the uptake capacities of sugarcane roots by several orders of magnitude. Contrary, fluxes of organic N closely matched roots’ uptake capacity. These results indicate root uptake capacity constrains plant acquisition of inorganic N. This mismatch between soil N supply and root N uptake capacity is a likely key driver for low N efficiency in the studied crop system. Our results also suggest that (i) the relative contribution of inorganic N for plant nutrition may be overestimated when relying on soil extracts as indicators for root-available N, and (ii) organic N may contribute more to crop N supply than is currently assumed.

PERAN KOMPOS TANDAN KOSONG KELAPA SAWIT DAN PUPUK ANORGANIK DALAM MENINGKATKAN SERAPAN HARA N, P, K DAN PERTUMBUHAN TANAMAN KENAF (Hibiscus cannabinus L.)

“…Akumulasi hara tersebut termineralisasi bertahap dan digunakan oleh tanaman padi secara berturut-turut. Secara umum aplikasi pupuk N hanya sekitar 50 % yang dapat ditangkap oleh tanaman, sisanya menjadi polusi melalui run off, leaching dan emisi gas nitrogen (Brackin et al, 2015). Tabel Hasil penelitian Sun et al (2015) menunjukkan bahwa kombinasi aplikasi pupuk NPK dengan pupuk organik secara signifikan meningkatkan kelimpahan komunitas mikrobia yang terlibat dalam siklus nitrogen yaitu bakteri nifH, archaeal dan bacterial amoA, nirS, nirK dan nosZ.…”

Agronomic performance of green cane fertilized with ammonium sulfate in a coastal tableland soil

“…The present study's soil has a low CEC, thus the relatively higher NUE reported would be mainly associated to the retention of fertilizer N by soil microbial biomass, which was favoured by the high C:N ratio of soil organic matter. The slower N turnover through microbial and organic pools would be more closely matching root N uptake (Brackin et al 2015), increasing fertilizer N recuperation by the plant.…”

“…According to Brackin et al (2015), the increase in mineral N availability after fertilization exceed in several orders of magnitude (200 to 3,000%) the N uptake by sugarcane roots. The N in excess is retained by charged soil particles, lost from the system or immobilized by soil microorganisms.…”

Contributions of rational soil tillage to compaction stress in main peanut producing areas of China

“…Moreover, an arrested development of roots had substantial effects on the nutrient uptake and organic composition of crops20212223. Except for root disruption, other underground parts were directly inhibited by soil compaction for underground crops2425.…”