Nitrogen fertilization and planting models regulate maize productivity, nitrate and root distributions in semi-arid regions

Shortages in soil water and nutrients resources, and low water productivity, are convincing growers to implement a sustainable water saving technology. Production of maize is greatly affected by nitrogen fertilization and planting models strategies through regulating root and (NO3--N) distributions. In this study, we established two planting models, i.e. furrow planting with ridges film mulching (PN); traditional flat cultivation (TN), with four 0, 150, 250 and 350 kg N ha(-1) fertilization levels. The results indicated that the effect of planting models in combination of N fertilization levels on soil moisture, root distribution and maize production were significant. The total root length (TRL), total root dry weight (TRDW) and average root diameter (ARD) under the TN occurred the appearance peak time (t(e)) and maximum growth rate (t(m)) more earlier, whereas those in PN treatments delayed under various N levels. The average growth rate (C), maximum growth rage (c(m)) and maximum values (W-max) of ARD, TRDW and TRL were significantly higher under the PN350 and PN250 than that of TN treatments. The gray correlation coefficients in the middle and lower depths of soil among ARD, RDWD and RLD under the PN were remarkably maximum then those in TN under various N levels. These gray coefficients in the top soil profile of 0-40 cm were significantly lower under the PN, whereas these coefficients above 60 cm soil depths were clearly greater compared with TN. The increased RDWD, RLD and ARD under the PN350 treatment help to develop the root system, improve the water and nutrient absorption ability in deeper depths of soil, as a result significantly improve grain yield (58 %), RUE (49 %) and AEN (38 %) of maize than that of TN350 treatment. In the upper-most (0-10 cm) depth of soil the RLD was significantly higher at flowering and maturity stage under PN350 compared with TN350 treatment. In addition, at the deeper soil layer below 40 cm, there were no significant variations in RLD. Under PN treatment significantly improved, the root bleeding sap at jointing and flowering stage. In addition, the NO3--N contents under PN350 were significantly higher than those under TN treatments. The above results indicated that PN350 and PN250 improve RUE, AE(N) and maize production by regulating root and (NO3--N) distribution.