Abstract

Fertigation in rice-based cropping systems is catching up the attention of farmers for producing high yield of crops and improved fertilizer use efficiency. As fertigation with different combinations of irrigation and nitrogen (N) levels can interact with depth of rooting system of different crops as well as soil tillage, this study was carried out in 2017 in the fourth year of on an on-going long-term experiment initiated in the summer (Kharif) season of 2014 to understand the effect of fertigation on soil organic carbon pools and yield in zero-till direct-seeded rice-based cropping systems. The experiment was laid out in a split plot design with three levels of fertigation as main plots: N @ 20 kg ha⁻¹ in rice through fertigation followed by 200 mm irrigation in post rice crops (W₁), N @ 40 kg ha^−1, in rice through fertigation followed by 300 mm irrigation in post rice crops (W₂), N @ 60 kg ha^−1, in rice through fertigation followed by 400 mm irrigation in post rice crops (W₃). The sub-plot treatments consisted of zero till direct seeded durum wheat, barley, chickpea, linseed, lentil and lathyrus crops after rice. The rice crop was also under zero till direct seeded cultivation system. The highest grain yield of rice was observed in the rice-lathyrus cropping system with treatment W₃ where N was applied in three equal splits, first being basal application and the two subsequent applications through surface inline drip irrigation. Both in surface and sub-surface soil layers, soil carbon stock, carbon pools and aggregate associated carbon were found to be more in the legume based cropping systems and with W₃ fertigation regime than in other cereal based cropping systems. The grain yield was found negatively and highly significantly correlated with less labile pool (r=-0.63**) whereas very labile pool was positively significantly correlated with labile (r = 0.89**), less labile (r = 0.53**) and non-labile (r = 0.91**) pools of carbon. Overall, fertigation levels influenced the crop yield and soil organic matter in zero-till direct-seeded rice-based cropping systems.

摘要

以水稻为基础的种植系统中的灌溉施肥正引起农民的注意，以提高作物产量和提高肥料利用率。由于灌溉和氮（N）水平不同组合的灌溉施肥可以与不同作物的根系深度以及土壤耕作相互作用，因此本研究于 2017 年的第四年进行了一项正在进行的长期试验于 2014 年夏季 ( Kharif ) 季节启动，以了解在零耕直播水稻种植系统中施肥对土壤有机碳库和产量的影响。该实验采用裂区设计，三个水平的施肥作为主要地块：通过施肥在水稻中施肥 N@20 kg ha ^-1，然后在稻后作物中灌溉 200 毫米（W₁ ), N @ 40 kg ha ^-1,水稻施肥后灌溉 300 mm (W ₂ ), N @ 60 kg ha ^-1,水稻施肥后灌溉 400 mm (W ₃ )。次小区处理包括在水稻之后从零到直接播种的硬质小麦、大麦、鹰嘴豆、亚麻籽、扁豆和香豆作物。直到直播系统，水稻产量也低于零。_{W 3}处理的水稻-稗草种植系统水稻产量最高其中 N 分三等份施用，第一次是基础施用，随后两次是通过地面在线滴灌施用。在表层和次表层土壤层中，发现以豆类为基础的种植系统和 W ₃施肥方式的土壤碳储量、碳库和聚集体相关碳比其他谷物种植系统中的多。发现谷物产量与不太不稳定的池呈负相关且高度显着相关（r = -0.63**），而非常不稳定的池与不稳定（ r  = 0.89**）呈显着正相关，不太不稳定（ r  = 0.53**）和不稳定（r = 0.91**) 碳库。总体而言，施肥水平影响了零耕直播水稻种植系统中的作物产量和土壤有机质。