Effects of Corn Intercropping with Soybean/Peanut/Millet on the Biomass and Yield of Corn under Fertilizer Reduction

Likun Li,Fajun Chen,Guangnan Xing,Yan Zou,Yanhui Wang

doi:10.3390/agriculture12020151

Abstract

Corn (Zea mays L.) is one of the key grain crops in China. In fields, the two crops of soybean (Glycine max L.) and peanut (Arachis hypogaea L.), which have nitrogen-fixing capacity (NFC), are generally used to intercrop with corn to improve plant physiology and production ability of corn even under fertilizer reduction. To explore a more scientific and reasonable way to plant corn, and simultaneously reduce the use of chemical fertilizers and pesticides, the impacts of corn intercropping with two NFC crops (including soybean and peanut) and the a non-NFC crop (i.e., millet (Setaria italica)) through five planting patterns, including three intercropping patterns (2 corn rows to 2, 3, and 4 NFC-crop rows or 2, 4, and 6 millet rows) and two sole crop patterns of corn and soybean, peanut, or millet under normal (600 kg/ha) and reduced (375 kg/ha) levels of NPK (N:P2O5:K2O = 15:15:15) fertilization levels on the activity of N-metabolism-related enzymes in corn rhizosphere soil and corn leaves, and plant biomass and yield of corn were researched in this study. The results showed that fertilizer reduction significantly decreased the plant biomass and grain yield of the sole crop corn. The intercropping type and planting pattern both had significant effects on the activities of N-metabolism-related enzyme of soil alkaline protease (S-ALPT), and glutamine oxoglutarate aminotransferase (GOGAT), glutamate synthetase (GS), and nitrate reductase (NR) in the leaves of corn plants. The intercropping type of corn with soybean through the planting pattern of 2 corn rows to 4 soybean rows significantly improved the activities of N-metabolism-related enzymes in soil and corn leaves even under the fertilizer reduction. The intercropping pattern of corn-soybean was the most beneficial to increase the total nitrogen content in soil and corn leaves. In addition, the intercropping significantly increased the soil microbial diversity under normal fertilizer. Furthermore, fertilizer reduction significantly increased soil microbial diversity of the corn sole crop. Therefore, it is concluded that for corn in intercropping systems, the best and the worst companion crop were, respectively, soybean and millet.

Highlights

Intercropping means that two or more crops are planted in the same farmland system and closely mixed during the whole or part of a growing season [1], and it has a history of thousands of years in China [2]
The interaction between intercropping type and planting pattern had a significant effect on corn biomass in the jointing stage (p < 0.001), and the interaction between fertilizer level and planting pattern had a significant effect on corn biomass in the dough stage (p = 0.003)
The results showed that the activities of N-metabolismrelated enzymes and the grain weight per plant and grain yield of corn intercropped with soybean and peanut were significantly increased with the increase of the row ratio of soybean and peanut intercropping with corn, especially in the planting pattern of 2 corn rows to 4 soybean/peanut rows (i.e., C2S4 and C2P4), even under reduced fertilizer application

Summary

Introduction

Intercropping means that two or more crops are planted in the same farmland system and closely mixed during the whole or part of a growing season [1], and it has a history of thousands of years in China [2]. As the most representative planting system, intercropping has been widely used in agriculture production because it can enhance the complementarity and utilization of temporal and spatial patterns of nutrients and environmental resources [3,4]. Intercropping can make full use of soil nutrients, enhance crop yield, and improve soil fertility [5]. The biomass of corn could be increased under the intercropping of corn-velvet bean, which would be increase the yield of corn green feed [6]. Intercropping increases habitat diversity and has a positive effect on increasing crop yields, increasing species diversity, and reducing pests and diseases [9]. Intercropping is called the “New Green Revolution” of agricultural sustainability intensification [10]. Intercropping can inhibit the occurrence of diseases and insect pests in the agroecosystem [11,12,13]

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