基于农田管理分区的制种玉米产量估算与限制因子评价

为了提升规模化农田不同管理分区的玉米产量,实现精准管理,该研究使用相关成分回归法(Correlated Component Regression,CCR),考虑地形因素(高程)、土壤理化性质(砂粒、粉粒、黏粒、容重、土壤含水率、土壤有机碳、全氮、全磷、速效氮、电导率)11个因子,评估规模化农田和聚类分析得到的3个管理区(M1、M2和M3)内产量的限制因子,并在不同分区内建立产量估算模型。模型验证结果表明:未分区的情况下,产量限制因子为土壤粉粒、砂粒、土壤有机碳、土壤含水率、速效氮和全氮,经验证,产量估算模型的决定系数(R~2)为0.70,标准均方根误差(Normalized Root Mean Square Error,nRMSE)为0.21。分区后,M1的产量限制因子为土壤粉粒、砂粒、黏粒、速效氮、电导率、全氮和全磷,M2的产量限制因子为土壤粉粒、砂粒和土壤含水率,M3的产量限制因子为高程、土壤砂粒、黏粒和电导率,产量估算模型的精度高(经验证,0.71R20.83,0.16nRMSE0.18)。对农田进行分区管理,并根据各管理区内作物产量的限制因素制定分布式管理策略,可以更具针对性地提升作物产量。

Evaluation of limiting factors and prediction of seed maize yield based on management zones

In order to improve the maize yield in different management zones and achieve precision agricultural management within a large-scale field, Correlated Component Regression (CCR) was used to screen limiting factors of maize yield from topographical attributes (elevation), soil physical factors (sand, silt, clay, bulk density), and initial soil properties (soil organic carbon, total nitrogen, total phosphorus, soil water content, available nitrogen, electrical conductivity). Yield estimation model was established based on yield-limiting factors in each management zone and the whole field. Management zones were delineated by using the Fuzzy c-means Clustering Algorithm (FCM) based on the spatial variation of soil properties. For soil properties, statistically significant differences in most cases were found among different management zones (M1, M2, M3), excepted elevation, silt, and clay. The decrease in the Coefficient of Variation (CV) of soil properties in the management zones indicated that the distribution of soil properties was more homogeneous than in the whole field. Spatial distribution of yield and management zones were similar, while the yield was significantly different in the three management zones (M1>M2>M3). The inhomogeneous spatial distribution of soil properties showed that the limiting factors of yield could be varied among management zones. Therefore, this study was to find out the yield-limiting factors, establish yield estimation models based on yield-limiting factors, and find ways to improve the yield in each management zone within a field. Four correlated components (CC1-CC4) were obtained in management zones and the whole field by CCR. The factors with largely standardized loadings (absolute value of standard loadings was greater than 0.2) on major correlated components (values of standardized weights were greater than 0.7) were identified as the main limiting factors of maize yield in zones. Yield in three management zones was measured and the limiting factors of yield in different zones were evaluated. The results showed that limiting factors for yield were silt, sand, soil organic carbon (SOC), soil moisture content (SWC), available nitrogen (AN), and total nitrogen (TN) in the whole field, which was different from management zones. The limiting factors of M1 were silt, sand, clay, AN, electrical conductivity (EC), TN, and total P (TP). Limiting factors of M2 were silt, sand, SWC, while the limiting factors were elevation, sand, clay, and EC for M3. Different yield estimation models were established by using CCR in management zones and the whole field. The correlation between simulated and measured yield was high, with R2 of 0.75 and nRMSE of 0.20 in the whole field; in management zones, higher simulation accuracy was found: the R2 of yield estimation model was 0.91, 0.84, and 0.76, while nRMSE were 0.15, 0.14, and 0.16 in M1, M2, and M3, respectively. For model validation, the R2 values were 0.70, 0.83, 0.78, and 0.71, while nRMSE were 0.21, 0.16, 0.18, and 0.17 in the whole field, M1, M2, and M3, respectively. According to the results, different ways of improving yield were found. For the whole field, soil amelioration and fertilizer application before sowing were the keys to increase yield. The application of organic fertilizer and phosphorus fertilizer, reduction of soil EC, and the improvement of soil water holding capacity were conducive to the improvement of yield in M1. Because soil texture and SWC were the main factors limiting the yield, improving soil water holding characteristics was also the way to increase yield in M2. For M3, irrigation before sowing could decrease EC of surface soil and improve soil water storage, which was beneficial to the emergence and growth of maize. Organic fertilizer application should also be considered for yield improvement in M3. Distributed management should be adopted based on the limiting factors of maize yield in management zones.