Breaking Soybean Yield Barriers: Integrating Crop Production Practices & Comprehensive Fertilization Strategies – a Cropping System Approach

This project is studying the effects of different farming systems on soybean yield in the major production regions of the Americas. The objectives are to: (1) quantify soybean yields across various production and fertilization practices; (2) quantify the yield gap between common farmer practice and more intensive management systems; (3) measure nutrient uptake and removal; and (4) examine nutrient partitioning between soybean plant organs. Field experiments were conducted in the 2016/17 season at Ponta Grossa (Parana) and Itiquira (Mato Grosso) in Brazil and Oliveros (Santa Fe) in Argentina, and in 2017 near Scandia (Kansas, USA).

The experiments at Ponta Grossa and Itiquira evaluated different combinations of nitrogen (N), phosphorus (P), potassium (K), sulfur (S), micronutrient fertilization, and liming. Average yields were lower at Ponta Grossa than Itiquira where soybean averaged 4,794 kg/ha and 5,423 kg/ha, respectively. While in the maize phase, yields averaged 15,588 and 7,926 kg/ha for Ponta Grossa and Itiquira, respectively. There was no significant response to treatments observed. A study on nutrient accumulation and partitioning on a modern variety has also been carried out at Ponta Grossa.

The experiment at Oliveros evaluated four treatments: common practice (CP); comprehensive fertilization (CF), or CP plus fertilizer input (N, P, K, S, and micronutrients); production intensity (PI), which included narrower rows and higher population, but no fertilizer; and ecological intensification (EI), or PI plus fertilizer input. Soybean yield was in the range of 4,000 to 4,500 kg/ha. Production intensity significantly improved grain yields by 6%, but fertilizer management just tended to increase yields by 4%. In maize, grain yields were between 7.3 and 11.3 t/ha. Grain yield increased by 44% under PI or EI. Fertilization management did not affect yield in late-planted maize (CF and FP treatments), and increased yield by only 4% in the production intensity treatment (comparison PI vs. EI).

The Scandia site included both dryland and irrigated experiments. Treatments included the same four as Oliveros, plus an advanced (AD) treatment, which was EI plus micronutrients and fungicides. Under dryland, average yield was 4,200 kg/ha (range 2,880 to 5,690 kg/ha). Overall irrigated soybean yield was 4,350 kg/ha (range 2,950 to 5,490 kg/ha). Under both water conditions, the treatments of EI and AD showed the highest yields with differences with PI under irrigated conditions. There were no differences between EI and AD at both water environments. CF and PI yielded more than CP under irrigation (750 and 1,200 kg/ha). Production intensification with balanced nutrition (EI, AD) produced 55% and 58% more yield than CP for dryland and irrigated conditions. After four years of rotation in high yielding environments (irrigated), CP yields differed statistically from all other treatments showing the negative impact of the lack of a balanced nutrition program in the production system. The study is planned to continue in 2018.