[Effects of water-fertilizer coupling on the yield of spring maize under shallow-buried drip irrigation in semi-arid region of western Liaoning Province]. / æµ åŸ‹æ»´çŒæ°´è‚¥è€¦åˆå¯¹è¾½è¥¿åŠå¹²æ—±åŒºæ˜¥çŽ‰ç±³äº§é‡çš„å½±å“.

To reveal the coupling effect of water and fertilizer on the yield of spring maize under shallow-buried drip irrigation in semi-arid area of western Liaoning, a field experiment was conducted with the quadratic regression orthogonal design of three factors (water, nitrogen and potassium) crossed with five levels in 2017-2018. A quadratic regression model was established with yield (Y) as the dependent variable and irrigation amount (W), nitrogen (N) and potassium (K) application amounts as independent variables to analyze the coupling relationships between Y and W, N and K, respectively. The results showed that the shallow-drip irrigation water-fertilizer coupling had significant impact on yield. The single factor of W, N and K promoted the yield, with their effects ranking as W>N>K. The effect of two-factor interaction on yield increased first and then decreased which ranked as WN>WK>NK. Considering the three-factor coupling effect on yield, the combination of abundant water, nitrogen and potassium was the highest, followed by high water, nitrogen and potassium, and low water, nitrogen and potassium the lowest. As the optimal treatments found by the model, we obtained the suitable water-fertilizer application range of shallow-buried drip irrigation with higher target yield of 8000-8810 kg·hm-2, that was, the irrigation amount was 43-61 mm, nitrogen 138-343 kg·hm-2 and potassium 79-163 kg·hm-2 under the ambient natural rainfall. The results provided a referable basis for application of water-fertilizer integrated cropping pattern under shallow-buried drip irrigation in semi-arid area of northern China.

Effects of stubble and mulching on soil erosion by wind in semi-arid China.

Soil erosion is a growing challenge for agricultural production in Northern China. To explore the effect of variation in stubble height and mulching biomass on soil erosion caused by wind, we conducted a field experiment using a quadratic rotation combination design. Results showed that the quantity of straw mulch was the dominant factor affecting soil erosion, and stubble height was of secondary importance. The soil water content in stubble and straw mulching treatments was higher than in a control treatment at 0-20 cm soil, and the tendency in the amount of soil water content was opposite to the amount of wind erosion (r = -0.882, n = 10, p < 0.01). The change in soil water content observed in the stubble and mulch treatments at the 15-20 cm depth was higher than the change from 0-5 cm to 5-10 cm. Combined, the influence of a stubble height of 34 cm and mulch quantity of 4260 kg·ha(-1) lowered the amount of erosion to 0.42 t·ha(-1), and increased the corn yield to 11900 kg·ha(-1). We determined that those were the most appropriate levels of stubble height and straw mulch for crop fields in the semi-arid regions of Northern China.

Biochar Improves Soil Aggregate Stability and Water Availability in a Mollisol after Three Years of Field Application.

A field experiment was carried out to evaluate the effect of organic amendments on soil organic carbon, total nitrogen, bulk density, aggregate stability, field capacity and plant available water in a representative Chinese Mollisol. Four treatments were as follows: no fertilization (CK), application of inorganic fertilizer (NPK), combined application of inorganic fertilizer with maize straw (NPK+S) and addition of biochar with inorganic fertilizer (NPK+B). Our results showed that after three consecutive years of application, the values of soil bulk density were significantly lower in both organic amendment-treated plots than in unamended (CK and NPK) plots. Compared with NPK, NPK+B more effectively increased the contents of soil organic carbon, improved the relative proportion of soil macro-aggregates and mean weight diameter, and enhanced field capacity as well as plant available water. Organic amendments had no obvious effect on soil C/N ratio or wilting coefficient. The results of linear regression indicated that the improvement in soil water retention could be attributed to the increases in soil organic carbon and aggregate stability.

Maize yield response to water supply and fertilizer input in a semi-arid environment of Northeast China.

Maize grain yield varies highly with water availability as well as with fertilization and relevant agricultural management practices. With a 311-A optimized saturation design, field experiments were conducted between 2006 and 2009 to examine the yield response of spring maize (Zhengdan 958, Zea mays L) to irrigation (I), nitrogen fertilization (total nitrogen, urea-46% nitrogen,) and phosphorus fertilization (P2O5, calcium superphosphate-13% P2O5) in a semi-arid area environment of Northeast China. According to our estimated yield function, the results showed that N is the dominant factor in determining maize grain yield followed by I, while P plays a relatively minor role. The strength of interaction effects among I, N and P on maize grain yield follows the sequence N+I >P+I>N+P. Individually, the interaction effects of N+I and N+P on maize grain yield are positive, whereas that of P+I is negative. To achieve maximum grain yield (10506.0 kg · ha(-1)) for spring maize in the study area, the optimum application rates of I, N and P are 930.4 m(3) · ha(-1), 304.9 kg · ha(-1) and 133.2 kg · ha(-1) respectively that leads to a possible economic profit (EP) of 10548.4 CNY · ha(-1) (CNY, Chinese Yuan). Alternately, to obtain the best EP (10827.3 CNY · ha(-1)), the optimum application rates of I, N and P are 682.4 m(3) · ha(-1), 241.0 kg · ha(-1) and 111.7 kg · ha(-1) respectively that produces a potential grain yield of 10289.5 kg · ha(-1).

Quantifying spatial variability of selected soil trace elements and their scaling relationships using multifractal techniques.

Multifractal techniques were utilized to quantify the spatial variability of selected soil trace elements and their scaling relationships in a 10.24-ha agricultural field in northeast China. 1024 soil samples were collected from the field and available Fe, Mn, Cu and Zn were measured in each sample. Descriptive results showed that Mn deficiencies were widespread throughout the field while Fe and Zn deficiencies tended to occur in patches. By estimating single multifractal spectra, we found that available Fe, Cu and Zn in the study soils exhibited high spatial variability and the existence of anomalies ([α(q)max-α(q)min]≥0.54), whereas available Mn had a relatively uniform distribution ([α(q)max-α(q)min]≈0.10). The joint multifractal spectra revealed that the strong positive relationships (r≥0.86, P<0.001) among available Fe, Cu and Zn were all valid across a wider range of scales and over the full range of data values, whereas available Mn was weakly related to available Fe and Zn (r≥0.18, P<0.01) but not related to available Cu (r = -0.03, P = 0.40). These results show that the variability and singularities of selected soil trace elements as well as their scaling relationships can be characterized by single and joint multifractal parameters. The findings presented in this study could be extended to predict selected soil trace elements at larger regional scales with the aid of geographic information systems.