Response of fertilization effect of maize to inherent soil productivity in Henan Province

Objectives A total of 885 “3414” field experiments were conducted in Henan Province from 2005 to 2013, and the data were collected to evaluate maize yield, the economic benefit and the utilization efficiency of N, P, K fertilizers under different inherent soil productivity to optimize fertilizer application.

Methods Five treatments of CK (N0P0K0), –N (N0P2K2), –P (N2P0K2), –K (N2P2K0) and NPK (N2P2K2) were imposed to "3414" maize fields. The inherent soil productivity of the 885 experiments was divided into four levels of < 4 t/hm², 4–6 t/hm², 6–8 t/hm², and > 8 t/hm² based on maize yield of the CK treatment. The data of yield, economic benefit, agronomic efficiency (AE), partial factor productivity (PFP), fertilizer contribution rate (FCR) and contribution rate of inherent soil productivity were collected.

Results The proportion of inherent soil productivity level of < 4 t/hm², 4–6 t/hm^2, 6–8 t/hm², and > 8 t/hm² accounted for 15.35%, 49.42%, 29.42% and 5.81% of the total 885 experimental fields, respectively. The yield increase amount of NPK treatments in four inherent soil productivity levels was averaged of 3.04 t/hm², 2.49 t/hm², 1.88 t/hm² and 1.12 t/hm², respectively, and the differences were significant among the four levels. The yield increase rate showed even sharper down trend with the increase of soil productivity. The yield increase rate was 93.23% for the inherent soil productivity of < 4 t/hm² while that was 14.44% for the inherent soil productivity of > 8 t/hm². The gross income, fertilization cost, fertilizer profit and input–output ratio were improved significantly with the increase of the soil productivity levels. The gross income, fertilization profit and input-output ratio of NPK treatment were 10238 yuan/hm², 8862 yuan/hm² and 5.75 for the inherent soil productivity of < 4 t/hm², and 15407 yuan/hm², 13736 yuan/hm²and 8.05 for the inherent soil productivity of > 8 t/hm², respectively. The contribution rate of different inherent soil productivity was 53.24%, 67.68%, 78.80% and 86.63%, respectively, with an average contribution rate of 69.99%. The average contribution rates of inherent soil productivity of soil N, P and K were 78.32% (40.72%–100%), 88.47% (70.40%–100%) and 90.02% (78.27%–99.31%) respectively. In general, K contribution rate was highest, following by P and then N. The contribution rates of inherent soil productivity of N, P and K in soil were increased with the increase of inherent soil productivity level. The contribution rates of inherent soil productivity of N in soil were 65.08% (< 4 t/hm²), 77.04% (4–6 t/hm²), 85.32% (6–8 t/hm²) and 90.47% (> 8 t/hm²), respectively. The PFP increased, while the AE and FCR decreased with the increase of the soil productivity, indicating that enhancing soil indigenous fertility could reduce the yield dependence on chemical fertilizers.

Conclusions High soil indigenous fertility increased yield and economic benefit, and reduced the yield dependence on chemical fertilizers. Thus, it is critical to improve the inherent soil productivity, and use reasonable fertilization based on inherent soil productivity to ensure high and stable yield, improve fertilization efficiency, and achieve more economic benefits in maize production in Henan Province.