SITE-SPECIFIC NUTRIENT MANAGEMENT (SSNM)

Zhejiang, China

Team Leader

Dr. Guanghuo Wang

Professor of Soil Science

Department of Resources Science

Zhejiang University

Huajiachi Campus, Hangzhou 310029

Zhejiang, China

Email: ghwang@zju.edu.cn

Partner Institution

Zhejiang University

Site Characteristics

Zhejiang Province is located in the southeast of China, in the southern sector of the Yangtze River Delta. Two main rice-based cropping systems are practiced in Zhejiang:

§         Double rice with two rice crops per year: This system is common in central and southern Zhejiang with early rice grown from early April to July and late rice grown from mid July to late October. Inbred cultivars are usually grown in the early rice season, whereas hybrid cultivars are grown in the late rice season.

§         Single rice, also referred to as middle rice, with one rice crop per year: A hybrid Indica cultivar with about 135−140 day growth duration is grown from late May to early October at central and southern Zhejiang. A Japonica cultivar (hybrid or inbred) with about 155−160 day growth duration is grown from late May to the end of October or early November at northern Zhejiang, which may or may not be followed by a winter crop.

The climate is subtropical with warm temperatures and annual precipitation of 1100−1900 mm. Three main types of rice soils are found in Zhejiang:

§         Soils derived from alluvial deposits (40% of rice area). These soils occur in the valley plains along the upper and middle reaches of various rivers in Zhejiang. These soils vary greatly in terms of fertility and productivity.

§         Soils derived from lacustrine deposits, marine deposits, or alluvial-marine deposits (40% of rice area). These soils are found in coastal areas and river deltas, and usually have high organic matter content and fertility.

§         Various red soils (20% of rice area). Because of the relative low fertility of their parent materials, these soils belong to the medium- or low-yielding rice soils.

Development and Evaluation of SSNM

Research on the development of SSNM was conducted in pilot villages from 1997–2000 near the city of Jinhua in the central part of this province—in the Jinhua-Quzhou (Jin-Qu) Basin with about 395,000 ha irrigated rice land. The Jin-Qu Basin is important for commercial food production, not only at the provincial but also at the national level. Activities in 2001−2004 included research on N use efficiency and optimizing N management for direct wet-seeded early rice conducted in Jinhua, as well as extension and evaluation of SSNM to other locations in the province.

Research Results

Attainable yields and nutrient deficits

The nutrient omission plot technique was used to determine attainable yield with full fertilization and nutrient-limited yields. Table 1 shows the results averaged for eight villages in 1997−2004. Rice grain yield in plots fully fertilized with N, P, and K provided an estimate of the attainable yield target. The attainable yield target is 6–7 t ha⁻¹ for early rice, 7–7.5 t ha⁻¹ for late rice, 7.5–8.5 t ha⁻¹ for single hybrid Indica rice, and 8–9 t ha⁻¹ for single Japonica (inbred or hybrid) rice. The yield of rice not fertilized with N but fertilized with other nutrients was used to determine N-limited yield. Similarly, the yield of rice not fertilized with P but receiving other nutrients indicated P-limited yield; and the yield of rice not fertilized with K but receiving other nutrients indicated K-limited yield. The difference between the yield target and a nutrient-limited yield indicated the crop response to the nutrient. This response is usually ≤ 1 t ha⁻¹ for P and K in early rice, and ≤1 t ha⁻¹ for P and ≤ 2 t ha⁻¹ for K in late rice.

Table 1. Rice yields obtained with the nutrient omission plot technique in farmers’ fields in Jinhua in 1997−2004.

SD = standard deviation; n = number of replicated plots.

SSNM-based nutrient requirements

The SSNM approach was used to estimate fertilizer N, P₂O₅, and K₂O requirements based on the results in Table 1. Total fertilizer N required for rice (Table 2) was estimated from the measured response to N (Table 1) and an assumed target agronomic efficiency of N (kg yield increase kg fertilizer N⁻¹) of 15 for both the early and late rice seasons. See N management for more details.

Total fertilizer P₂O₅ and K₂O were estimated from attainable yield target, P-limited yield, and K-limited yield (Table 1) using the nutrient decision support system (NuDSS). Straw input was estimated as 2 t ha⁻¹.

Table 2. Fertilizer N, P₂O₅, and K₂O requirements estimated from results with the nutrient omission plot technique in Zhejiang, China in 1997−2004.

Locally Adapted Recommendation

Results from the nutrient omission plot technique and N use efficiency research were used to formulate locally adapted recommendations for managing N, P, and K. Recommendations for early, late, and single (middle) rice crops are available at the links below.

SSNM recommendation for transplanted early rice

Version 1.0 [PDF 146kb]

SSNM recommendation for direct-seeded early rice

Version 1.0 [PDF 147kb]

SSNM recommendation for transplanted late rice

Version 1.0 [PDF 153kb]

SSNM recommendation for transplanted middle rice (Indica)

Version 1.0 [PDF 153kb]

SSNM recommendation for transplanted middle rice (Japonica)

Version 1.0 [PDF 156kb]

Zhejiang, China SSNM version 1.0 (www.irri.org/irrc/ssnm)

Site Specific Nutrient Management