Forage productivity, quality and efficiency in sorghum (sorghum bicolor (l.) Moench) and soybean (glycine max (l.) Merr.) cropping systems in Los Baños, Laguna, Philippines

Date

7-2026

Abstract

In the Philippines, the rising demand for animal products, combined with high production costs and limited feed resources, highlights the need for sustainable local forage crop systems. Although sorghum and soybeans are recognized as forage crops, these crops are typically cultivated as monocultures, and their intercropping potential remains unexplored under local conditions. This study evaluated the effects of cropping system (sorghum monocrop, soybean monocrop, sorghum and soybean intercrop) and nitrogen (N) fertilization rates (0, 30, 60, 120 kg N ha-1) on the growth, biomass yield, quality, and resource-use efficiency of sweet sorghum (SPV 422) and soybeans (NSIC Sy 17) across the wet and dry seasons. The treatments, comprising of eight cropping system x N rate combinations arranged under a 2:2 paired-row intercropping configuration, were laid out in a randomized complete block design with three replications.

Results showed that sorghum and soybean intercropping combined with moderate N fertilization (60 kg N ha-1) improved system performance across productivity, quality and efficiency metrics. Biomass yield was 8% lower in sorghum monoculture but 106% higher than in soybean monoculture. Crude protein content increased by 24% relative to sorghum monoculture but remained 55% lower than in soybean monoculture. Neutral detergent fiber is reduced by 6%. Intercropping improved land-use efficiency (LER=1.03) and increased nitrogen-use efficiency (NUE) by 23-30% compared with monocultures, while reducing synthetic N requirements by approximately 50%. These outcomes reflected strong complementarity between C4 sorghum and C3 soybean, with biological nitrogen fixation contributing to the system’s N supply.

Also, moderate N application (60 kg N ha-1) maximized returns by increasing net income, monetary advantage index, and benefit-cost ratio, while lowering production costs through improved LER and NUE. The sorghum and soybean intercrop system also supported up to 50% higher livestock carrying capacity due to increased effective dry matter yield. Overall, sorghum and soybean intercropping with 60 kg N ha-1 demonstrated balanced improvements in productivity, forage quality, resource-use efficiency, and profitability.

Document Type

Dissertation

Degree

Doctor of Philosophy in Agronomy

College

Graduate School (GS)

Adviser/Committee Chair

Ma. Lourdes S. Edaño

Committee Member

Eureka Teresa M. Ocampo, Roselyn F. Paelmo, Arnel N. Del Barrio, Jessica Villanueva-Peyraube

Language

English

En – AGROVOC descriptors

SORGHUM BICOLOR; FORAGE SORGHUM; GLYCINE MAX; INTERCROPPING; NITROGEN FERTILIZERS; CROP PRODUCTION; PROFITABILITY; RESOURCE USE EFFICIENCY

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